PetroWiki

ERW

A well deviated above the pay to reach further from the drill site or further into the pay formation to expose my contact area with the pay zone. Abbreviated ERW.

Dilatant fluid

A well dispersed, high solids content liquid that has very high apparent viscosity with any applied shear.

COST well

A well drilled on the continental margin to provide data for offshore leases.

Extension well

A well drilled on the edge of the existing field that may extend the known area of the field.

Gravity survey

A exploration method that uses an instrument to measure the intensity of the earth's gravity. Areas with unusual readings may indicate traps or structures that could contain hydrocarbons.

Extraction plant

A facility for removal of liquids from gas.

Embrittlement

A fatigue state of metal that may be caused by trapping atomic hydrogen in the structure of the steel. Characterized by loss of ductility. May also be caused by work hardening or other factor.

Dutchman

A filler piece used to close a gap in piping or equipment alignment.

Absolute filter level

A filter rating that purports to set the maximum size of an opening in a filter or the maximum size of the particle that can pass through the filter.

Cartridge filter

A filtering device that uses replaceable cartridge elements to filter liquids to a required level.

Blind flange

A flange plate without an opening, normally used as seal-off assurance over an unused line.

Blind box

A flat bottom, short steel tool run on wireline to tag the surface of water or solids in the well. It is nearly the drift diameter of the tubular.

Downhole choke

A flow bean (restriction) set in a profile near the bottom of the well. Used as a flow regulator and to take part of the pressure drop downhole to reduce the potential of hydrates.

Back presssure valve

A flow control valve that provides some control when running or pulling a string.

Bean

A flow restriction common in downhole chokes, surface chokes and some SSSVs.

Flow bean

A flow restriction common in downhole chokes, surface chokes and some SSSVs.

Flow test

A flow test designed to prove that hydrocarbon exists in the reservoir and will flow to surface. May also indicate productivity or other characteristics such as interference or boundaries.

Four point tests

A flow test in which the flow rate is measured at four drawdowns to estimate how skin changes at each rate. Useful for identifying non Darcy skin or turbulent skin.

Cut fluid

A fluid that has been contaminated by an undesirable fluid.

Gel

A fluid with a higher than normal viscosity created by a gallant material such as polymer.

Consistency

A fluid's ability to deform and flow and its general cohesion to itself.

Defoamer

A foam breaking chemical.

FoxRo Log

A focused resistivity log that uses a pad contact with the borehole wall.

Cohesion

A force that holds fluids and sand grains together. The force is generated by attraction at the molecular level. Cohesion is often used to describe sand grains stuck together by a low viscosity fluid such as oil or water, although this is better explained as adhesion.

Call option

A form of a financial option which entitles the owner to purchase one share of a commodity at a specific (strike) price on or before a specific (exercise) date.

American option

A form of financial option that allows the purchase on or before the exercise date.

European Option

A form of financial option that requires that the purchase be made on the exercise date; expected value.

Evaporite

A formation formed by the evaporation of water from shallow seas. Very low permeability.

Disbond

A formation that comes apart or disaggregates or separation of grains.

Abnormally pressured formation

A formation which has its pore pressure is above or below the pressure dictated by the pressure gradient of hydrostatic column.

Butane

A four carbon chain alkane, may be a liquid in the reservoir, but vaporizes as pressure is released. Part of the natural gas liquid components.

Flow cross

A four-way connection. In a wellhead, a flow cross connects the master valve and the swab valve with two, normally horizontal, connections to the wing valves.

Carried interest

A fractional working interest in an oil and gas lease that arises from a deal between co-owners.

Brittle fracture

A fracture created with little or no plastic deformation.

Burst disk

A frangible disk designed to release pressure at a specific level.

Bunker c oil

A fuel oil, normally with high sulfur and high viscosity. API gravity of about 10.5o.

Drill pipe safety valve

A full opening valve with threads that match the drill pipe that can be quickly screwed onto the pipe to help control fluid flow up the tubing.

Bell nipple

A funnel shaped pipe at the top of the casing that guides tool string entry and may have a side port for fluid pumping.

Flow after flow

A multipoint flow test measuring skin at each flow rate. When plotted, the intersection of the best fit line with the y-axis (skin) at zero flow rate yields the mechanical skin.

Anionic surfactant

A negatively charged surfactant. Normally water wets sands.

Crazing

A network of checks or cracks appearing on the material surface.

Fixed choke

A non adjustable choke that uses a flow bean for regulation.

Acrylamide polymer

A nonionic polymer (polyacrylamide) used in flocculation, clarifying and even gelling acids and other brines. Very stable, but difficult to effectively break.

Coherency

A numerical measure of the similarity of reflection wave shapes in a user-specified data window. Coherency values are scaled to the numberical range +1 to -1. A value near +1 means the comparison wave shapes are identical; a value near -1 means the wave shapes are identical but have opposite polarities. A value near zero means the comparison wave shapes have little similarity.

Flapper valve

A one-way, flow actuated valve common in safety valves, coiled tubing and fluid loss devices.

Genetic sequence

A package of stratigraphic units that are genetically related. Genetic sequences are bounded by erosional surfaces, flooding surfaces, or maximum flooding surfaces.

Cup packer

A packer with elastomer cups that are pushed out during fluid injection as the primary seal. Used for washing perfs and some testing. Only seals during fluid injection.

Equalizing feature

A part of a plug that allows equalization of the pressures above and below a plug.

Alternate path technology

A patented screen design that allows gravel packing slurry to flow past an annular bridge point that would normally stop the placement of gravel.

Deep penetrating charge

A perforating charge with a liner shape designed to create a long penetration into the formation, but a smaller entrance hole in the pipe. See also Big Hole Charge.

Exposed guns

A perforating gun with exposed charge capsules.

Abrasive jetting

A perforating process involving pumping a slurry of liquid and size particles through a nozzle to cut through steel and rock.

Bridge plug

A permanent or retrievable plug set typically on wireline to isolate a section of the well.

Bleeding core

A permeable core from which hydrocarbon escapes without differential pressure application.

Emulsion

A physical mixture of two or more immiscible phases.

Fishing neck

A piece of equipment on most downhole tools that is designed for simple, non-rotating attachment when retrieving.

Adaptor

A piece of equipment that connects pipe, flanges or other equipment with different root threads or connection mechanisms.

External upset

A pipe connection with a thicker connection body than the pipe body. In an external upset, the thickness is offset to the outside diameter. Abbreviated EUE or EU.

Explosive cutter

A pipe cut-off tool composed of linear shaped charge that is designed to sever pipe. Works on the same principle as a perforating charge.

Chemical cutter

A pipe cutting tool that uses boron trifluoride sprayed through a nozzle at very high velocities.

Downcomer

A pipe where the fluid flow path is down. Fluid return pipe.

Cement plug

A plug of cement set by various methods that plugs the tubulars or the open hole.

Blanking plug

A plug run to seal off tubing.

DG Plug

A plug that is commonly set in the tubing hanger above the tubing or in tubing immediately below the wellhead for wellhead isolation.

Crosslinked

A polymer gel with a chemical crosslinker added to link the linear gel into a higher viscosity gel.

Allocated pool

A pool in which the total oil or gas production is restricted and allocated to specific wells as defined in a proration agreement.

Catatonic surfactant

A positively charged surfactant, normally oil wets sands.

AC Test

A precision sized micron particle material used for testing the solids stopping capability of filters.

Back pressure

A pressure caused by a restriction or fluid head that exerts an opposing pressure to flow.

Grease injector

A pressure control method for forming a pressure seal around braded line and electric line. Grease is injected between special tubes in a high pressure housing. The tubes are slightly larger than the line and grease seals the remaining area.

Gas lift valve

A pressure operated valve, placed in a gas lift mandrels at designed points in the well. The gas lift supply gas is routed through the valves into the tubing. The top valves close and the lower valves open as the static liquid level drops in the well (the well is unloaded).

Fusible vent

A pressure relief valve that opens when temperatures increases sufficiently to melt an activation linkage.

Adjustable choke

A pressure step-reduction choke that can be changed while actively flowing the well.

Casing shoe test

A pressure test of the casing seal, after the cement job, to the pressures necessary to safely control the pressure of the deeper zones.

Bactericide

A product that kills bacteria in the water or on the surface of the pipe.

Collar lock

A profile that can be set by wireline in the space in an API type coupling.

De-bottlenecking

A program, typically in surface facilities and lines, to remove pressure drop causing flow restrictions.

Dart

A pump-down fluid separation device. May also be used to operate tools downhole by hydraulic forces.

Berea sandstone

A quarried sandstone with from 4500 to 9000 psi UCS, used commonly in laboratory flow testing.

Butterfly valve

A quick opening, low pressure valve, common on large openings through which solids will move, that allows high flow rate when open.

Burr

A raised metal lip, e.g. around a perforation.

Distillates

A range of manufactured products from the refining processes, includes kerosene, diesel, bunker C oil, fuel oil, heating oil, etc.

Crude oil

A range of principally Carbon-Hydrogen chain compounds with generally straight carbon chain lengths of C1 (methane) to C60+. The straight chain materials are alkanes.

Explosive decompression

A rapid reduction in pressure that may cause trapped gas to try to break out of rubber/elastomer seals and ruin the seals. Common at the surface but uncommon downhole.

Flash set

A rapid, usually unplanned, thickening of cement.

Endothermic

A reaction that absorbs heat.

Acid

A reactive material with a low pH. Common oilfield mineral acids are HCl and HCl/HF.

API RP

A recommended practice published by the API.

Cement packer

A recompletion technique in which cement is injected down the tubing and through a punched hole in the tubing to form a 300 to 500 ft thick seal between the tubing and the casing, often far about the bottom of the well. Useful for isolation of upper zones to shut-off unwanted fluids or separate producing horizons.

Bit record

A record of bit run, depth, rate of penetration, etc., in a wellbore.

Deviation survey

A record of the deviation angle and the departure usually on a depth unit basis.

Caliper log

A recording of the diameter changes in a well made by a tool with mechanical arms that touch the wellbore or a sonic signal bouncing off the borehole wall.

Dynamometer

A recording of the stresses in a rod string of a beam pumping unit.

Datum

A relative comparison point, such as the Kelly bushing, sea level or mud line.

Condensate banking

A relative permeability effect where condensate, usually hydrocarbon, drops out of the vapor phase around the wellbore when the pressure drops below the dew point in response to drawdown or depletion. Gas rates can be severely reduced by the permeability reduction.

Completion bore protector

A removable sleeve that covers the internals of the subsea tree during drilling operations.

Corrosion coupon

A representative piece of metal cut to a specific size and shape that is immersed in a test bath of placed in the flow stream to enable an estimation of the active corrosion occurring in a given set of conditions.

Dissolved gas drive

A reservoir drive mechanism in which dissolved gas from the crude oil breaks out of solution and provides energy to push the hydrocarbons toward the wellbore.

Gas cap drive

A reservoir drive mechanism in which gas expansion in the gas cap pushes the oil towards the formation.

Alkyd

A resin formed by reaction of polyhydric alcohols and polybasic salts. Saturated or unsaturated oils or fats are involved.

Epoxy

A resin formed by reaction of polyols with epichlorohydrin.

Acrylic

A resin polymerized from one of several sources: acrylonitrile, acrylic acid, methacrylic acid, etc.

Bottleneck

A restriction in a flow path.

Cut lip guide

A type of cut on the bottom of an overshot that, when rotated, can help center the end of a pips that is laying against the side of the hole.

Gas lift side pocket mandrel

A type of gas lift mandrel that allows full bore passage. The valve "pocket" is on the side of the pipe.

Chamber lift

A type of gas lift that uses the tubing-casing annulus for accumulation of produced liquids between lift cycles.

Dope

A type of grease having some extra material like Zn or Pb. Dope is used to lubricate and seal the threaded connection.

Chain Tongs

A type of hand or power operated wrench used to make up connections in pipe.

Goodness of fit

A type of metric used to quantify how close a density function approximates a histogram.

Compressor

A type of pump that increases the pressure of gas. Commonly used as a production rate increaser by increasing the gas pressure delivered from low pressure gas wells to enter the pipe line. The intake into the compressor lowers the wellhead pressure creating a larger drawdown.

Duplex pump

A type of pump with two, dual acting pistons.

Fish hook

A upward turning horizontal well - usually over 90o.

Certainty Equivalent

A value obtained by trial and error with an individual or a group, toward which he/they would be indifferent between this value and a chance event.

Check valve

A valve that only allows flow in one direction.

Gate valve

A valve with a sliding bar - common in the oilfield as tree valves.

Flint

A variety of chert.

Absorber

A vertical, cylindrical vessel that recovers heavier (longer carbon chain) hydrocarbons from a mixture of lighter hydrocarbons.

Drill collar

A very heavy wall pipe used to add weight over the bit during drilling.

Barefoot completion

A very simple, open hole pay zone completion with a minimum of downhole equipment. Also called an open hole completion. The casing is usually run to the top of the pay and is cemented above the pay only.

Acetic acid

A very weak organic acid used for minor and shallow damage removal. Also used as a moderately effective iron precipitation preventer. 4% of this is vinegar

Brookfield rheometer

A viscosimenter use for some fluid measurements, particularly when solid suspension properties are needed.

Funnel viscosity

A viscosity measurement based on the number of seconds that it takes for 1 quartz of fluid to flow through a Marsh funnel.

Aquifer

A water containing formation that may or may not be directly connected to the hydrocarbon bearing zone. A connected aquifer may or may not offer pressure support to the pay.

Field weld

A weld repair made in the field. Usually derates the equipment pressure or tensile rating.

Bias weld

A weld technique on diagonal cut strips of steel, superior to the butt weld process for joining flat strips of metal together before rolling into coiled tubing.

Butt weld

A welded connection using two pipe ends, cut straight across and welded together with minimum circumferential contact.

Complex well

A well design with engineering or application challenges that are out of the ordinary.

Chromatogram

An analysis of hydrocarbons from a gas stream in order of molecular size.

Consolidated

An approximate level of rock strength where sufficient cementation is present to allow the rock to remain intact during drilling and production. Often the unconfined compressive strength is greater than 1000 to 1500 psi.

Beam pump

An artificial lift system, common to low pressure, lower rate oil wells, with a plunger type bottom hole pump operated from the surface by a rod string.

Gilsonite

An asphaltic drilling fluid loss additive.

Fischer assay

An assay method for organics in rock by pyrolysis (burning).

Band

An attachment strap to affix cable or capillary tube to the outside of the tubing.

Cable tool

An early drilling rig that uses a heavy chisel bit on a cable, dropped vertically, to pound through rocks.

Annular BOP

An elastomer bag or donut type seal, pushed into contact with the pipe or tools in the blow out preventer (BOP). It is designed to seal around pipe or any other irregular surface tool (packers, guns, pumps, etc.) that may be in the BOP, including itself if the wellbore is empty. May also be called a Hydril preventer.

Electrical Submersible Pump

An electrical powered rotating pump capable of lifting very large flow rates (>20,000 BPD). Abbreviated ESP.

Fusible plug

An emergency shutdown device activated by fire or thermal overload. (Note: fusible links below the ignition point in a wellhead may not be activated (melted)). Also called a fusible link.

Archie's equation

An empirical relationship between the formation resistivity, F, and porosity, φ, in which F=1/φm, where the porosity exponent or cementing factor, m, is a constant for a particular formation. Typical m's are 1.8 to 2.0 for consolidated sandstones and 1.3 for poorly consolidated sandstones.

Bean-up strategy

An engineered sequence of choke settings in the start-up of a well to apply stresses in the formation in a manner that will strengthen the formation and avoid failure.

Archean

An eon of geologic time extending from about 3.9 billion to 2.5 billion years ago.

Equivalent per million

An equivalent weight of an ion or salt per 1 million grams of solution or soil. For solutions, equivalents per million (e.p.m.) and milliequivalents per liter (meq/L) are numerically identical if the specific gravity of the solution is 1.0 as it is for freshwater at 20°C.

Carbide blast joint

An erosion resistant covering or main pipe that is used when tubing is set deeper than the perforations or on the long string across from the upper perforations in a side-by-side completion.

Collider

An explosive charge in a tool designed to sever very heavy BHA tools such as drill string collars and stabilizers. It latterly uses a focused explosive to blown the string apart. A tool of last resort.

Control head

An extension of a retrievable tool that is used to set and release the tool.

Flash point

An ignition temperature (given in oF) that liquid will put off enough vapors to be ignited.

Elongation

An increase in length expressed numerically as a percent of initial length.

Dual induction log

An induction log with dual and deep measurements of resistivity. Shallow measurements are indicative of severely invaded zone and the deepest measurements are most reflective of actual formation fluids.

Blasting cap

An initiating or detonating device in an explosive.

Geophone

An instrument that detects vibrations passing through the earth's crust.

Aluminium acitivation log

An investigation that focuses on aluminum content, an indirect measurement of clay content.

Capital assets

An investment or asset that can create a produce or service that will produce income.

Anion

An ion with a negative charge.

Batholith

An irregular intrusion of an igneous rock into another rock.

Bead tracer

An isotope tracer in a bead with the same density of the flowing fluid that is used to track fluid flow rates and therefore fluid entry and exit points along the wellbore.

Formation damage

An obstruction to flow. Usually a reduction of permeability.

Dry tree well

An offshore well with the wellhead and access to the well at the surface.

Grainstone

An often high permeability limestone where large grains are in contact. Only high perm if fines are absent.

Chalk

An often highly porous but lower permeability carbonate composed of fine grained marine sediments such a coccoliths.

Blind pool

An oil and gas partnership that has not committed to a specified project at the time of amassing capital.

Disposal well

A well into which fluids such as produced water and some liquid wastes can be injected. It is in a non hydrocarbon, non-fresh water sand and is not connected to the hydrocarbon bearing formation.

Five spot pattern

A well placement pattern that looks like the 5-spot side on a dice cube, with 4 injectors and 1 producer

Concurrent method

A well pressure control operation in which circulation is started immediately and mud density is brought up in steps until the well has been completely circulated to the kill weight fluid.

Dry hole

A well that does not have or produce commercial deposits of hydrocarbons.

Completed well

A well that has been drilled, cased and cemented and is ready to produce hydrocarbons.

Dead well

A well that will not flow on its own through natural gas lift or by reservoir pressure.

Deviated well

A well with an inclination other than zero degrees from vertical. In practice, deviated wells are usually more than about 10o from vertical.

Crooked hole

A wellbore drilled in excess of the maximum allowable dogleg.

Exploration well

A wildcat or well in a new area with unknown producing potential.

Dummy run

A wireline or tubing run into a well with a dummy piece of equipment of the same size, shape and stiffness of a valuable or unrecoverable piece of equipment to make sure the equipment can be placed.

Collar stop

A wireline set plug without a profile. It is set in a coupling and grips with packer-like slips.

Electrical line

A wireline with a conductor in the middle and woven electrical braid over the conductor. Also called an e-line.

Braden head

An older (actually trademarked name) for the wellhead.

Concentric coiled tubing

A workover using a small diameter tubing inside the existing tubing. Usually done with a hydraulic workover rig or coiled tubing. Commonly used with a positive surface well pressure and seals on the smaller tubing in a live-well workover.

Bullet gun

An older perforating method where hardened steel bullets were fired from short barrels and designed to penetrate the casing, cement and formation.

Gage joint

An older well design process of using a single joint of the heaviest wall casing in the well just below the wellhead. (Note - this restricts access of fullbore tools to all points below the joint.)

Formic acid

An organic acid used in higher temperature wells for shallow damage removal.

Gas cap

A zone of free gas above an oil deposit. The gas cap occurs where the oil is oversaturated with gas (past the solubility limit). When a gas cap is not present at discovery, the oil is above the bubble point.

C Annulus

An outside annulus, next out from the B annulus, usually production casing x production casing or surface casing. (Note, there may be regional differences in the A, B, C annulus designations)

B Annulus

An outside annulus, one out from the A annulus, usually production casing x production casing or surface casing.

Farm-in

An outside party paying a concession owner all or a percentage of the drilling costs of a well in order to obtain a working interest in the land or well.

Angular unconformity

An unconformity in which the beds below the unconformity dip at different angles than the beds above it.

Blowout

An uncontrolled release of fluids from a well.

Gas kick

An unexpected and unwanted entry of gas into the wellbore during drilling or well operations.

Blank

An unperforated piece of casing or tubing in an otherwise perforated section. Used for isolation.

ACV

Annular circulation valve.

AFV

Annular flow valve.

AFP

Annular friction pressure.

AIS

Annular isolation sleeve.

APB

Annular pressure build up.

APRV

Annular pressure relief valve.

ASV

Annular safety valve.

AIV

Annulus Isolation Valve

AWV

Annulus wing valve.

Ground bed

Anodes buried in the earth to supply cathodic protection to equipment.

Cyclonite

Another name for RDX explosive

Box Tap

Another name for a tapered tap. Used to screw into boxed of connections.

Antifouling

Any action designed to reduce or prevent fouling (deposits) on a surface.

Degasser

Any device that helps remove gas from circulated fluid.

Gas show

Any indication of gas in the drilling fluid or cuttings that indicates gas production from a reservoir that has been drilled.

Cased hole log

Any of several radioactive, chemical or physical properties logs that are run in a cased hole environment. May be conveyed by electric line, coiled tubing, slick line (memory logs) or drill pipe (LWD).

Casing patch

Any of several repair systems designed to set a patch over a leak in a well.

Gaskets

Any of several replaceable seals in equipment or tools.

Ball valve

Any of several valves that rotate a ball with a flow passage to allow or deny flow.

Concentric operations

Any operation where a smaller tubing is inserted through a larger tubing string. Normally done with the wellhead in place. Often done with the well under pressure.

Flow wetted

Any piece of a tool or the well that is wetted by the produced fluid flow.

Body

Any portion of the wellhead or tree that contains wellbore pressure.

Fines control

Any process designed to minimize movement of otherwise mobile fines, typical size <44 microns.

Acid gas

Any produced gas, primarily H2, S, and CO2 that form an acid when produced in water.

Dispersant

Any substance that aids in breaking up a mass of individual particles, bubbles or droplets.

Bulk modulus

Applied stress over strain in volume. Typically represented by the variable 'K'.

APD

Approved permit to drill.

AG

Arabian Gulf.

Coarse

API designation of sand-type particles larger than 2000 microns.

Communication

Ability to circulate or pass fluids from one chamber in a well to another.

AQL

Acceptance quality level.

Corrosion-erosion

Eroding away of a protective film of corrosion product by the action of a process stream, exposing fresh metal which then corrodes.

AL

Artificial lift.

ALARA

As low as reasonably achievable.

ALARP

As low as reasonably practicable

Bracelet anodes

Clamshell-type rings of anodes that clamp around a pipeline.

Fly ash

Ash from the burning of coal. Used as an extender in several cements and as a plug component.

Assistant driller

Assistant driller.

Aggregation

Attraction and adherence of clumps of small particles.

Flocculation

Attraction, gellation and drop out of suspended particles from a liquid.

Adhesion

Attractive forces between unlike molecules or compounds. Example: the attractive forces between water molecules and the walls of a clean glass tube are stronger than the cohesive forces, this leads to an upward turned contact or meniscus at the wall.

AIP

Australian Institute of Petroleum.

AFD

Authorization for definition.

AFE

Authorization for expenditure.

Cratering

Collapse of part of the formation into the wellbore during drilling or completions. Also known as sloughing.

Bridging

Collection of materials, usually from the formation that interlocks at some point in the well, often in the annulus and may stop flow or stick the pipe in place.

Biased estimates

Estimates for which there is a correlation between the standardized errors and the estimated values (see Cross-validation ) or for which a histogram of the standardized errors is skewed.

Absolute ages

Estimation/measurement of age of a formation, fossil, etc., in years before the present.

Flanged-up

Completed

BPV

Back pressure valve.

Biogenic gas

Bacteria generated natural gas, found at shallow depths.

Anaerobic

Bacteria that can survive and multiply without oxygen.

Facultative

Bacteria that can survive either with or without oxygen.

Balance line

Balance line.

BOSS

Ball operated shear sub.

BOMA

Ball out mud acid.

BOE

Barrel of oil equivalent

B/D

Barrels per day.

BKB

Base Kelly bushing.

BF

Base flange.

BMX

Base management excellence.

BOC

Base operations camp.

Behind pipe reserves

Behind-pipe reserves are expected to be recovered from zones in existing wells, which will require additional completion work or future recompletion prior to the start of production.

BSR

Bending strength ratio.

BTX

Benzene , Toluene, Xylene

BTBcp

Beyond the best common process

BCF

Billion cubic feet

Biodegradation

Breakdown of a heavier oil to a lighter hydrocarbon by bacterial action.

Encapsulated breaker

Breaker in small pill-form particles that stays with the polymer and helps break the mud cake.

Bacterial degradation

Breaking down alkanes by bacterial action. Common by psedomonis and ultramonis bacteria and other bacterial strains that digest parts of the crude oil structures. Useful for remediating oil spills or tank bottom residuals.

BSI

British Standards Institute.

BTU

British Thermal Unit

Environmental Cracking

Brittle fracture of a normally ductile material in which the corrosive effect of the environment is a cause (NACE).

Air Can

Buoyancy device on a Spar.

Deflagration

Burning, decomposition or low order detonation of explosive.

BWOC

By weight of cement.

BWOB

By weight of the blend.

BWOW

By weight of water.

Corrosion resistant alloy

CRA, alloy intended to be resistant to general and localized corrosion of oilfield environments.

Anhydrite

CaSO4 formation. Usually formed as an evaporite from a drying lake of trapped sea water.

Calcite

Calcium carbonate, CaCO3. May be rock (limestone) or a scale formed from super saturated solution at the site of a chemical or physical upset.

Dolomite

Calcium/magnesium carbonate rock. Dolomite is formed by chemical modification of a limestone.

CAOF

Calculated absolute open flow

Finding and development cost

Capital costs from acquisition, exploration, drilling and completion costs of proved reserves.

CAPEX

Capital expenditure. Costs that apply to building or acquiring a capital asset

Cutrite

Carbide particles in a metal binder. Applied to the cutting surfaces of mills.

C and P

Cased and perforated.

Expanding cement

Cement with additives that promote volumetric cement expansion.

Fiber cement

Cement with small hair like fibers that build strength or help control fluid loss.

Conchoidal marks

Characteristic markings (ridges, tears, risers, etc.) on fracture surfaces after fatigue crack of fracture propagation (also known as beach marks, clamshell marks and arrest marks).

Clamshell marks

Characteristic markings (ridges, tears, risers, etc.) on fracture surfaces after fatigue crack of fracture propagation (also known as beach marks, conchoidal marks and arrest marks).

Beach marks

Characteristic markings (ridges, tears, risers, etc.) on fracture surfaces after fatigue crack of fracture propagation (also known as clamshell marks, conchoidal marks and arrest marks).

Acid flowback analysis

Chemical analysis of the acid concentration and other chemical and physical measurements in the returning acid.

Exothermic

Chemical reactions that gives off heat.

Chicksan

Chicksan™ is the trademarked name for a surface treating line connector that allows quick bends in high pressure pipe.

Cuttings

Chips of rock from the drilling process. They are circulated to the surface by the mud and separated in the screens and shaker. They are useful for identifying and correlating the formation.

Condition the mud

Circulate the well to remove cuttings and gelled mud prior to running the casing.

Bottom up

Circulating the bottom hole fluid to the top of the well.

Acid inhibitor

Acid corrosion inhibitor. Slows the acid attack on metal.

ACFM

Actual cubic feet per minute.

Belt effect

Added friction in a deviated well as wireline or coil rubs against the top of the deviated section as the tube or cable is pulled out of a well.

Gas spiking

Adding gas to an injected fluid or treatment to reduce the injected water volume and provide energy for flowing the well back after the treatment.

Appraisal well

Additional wells drilled after a discovery, to confirm the size of a hydrocarbon deposit. Normally used to run buildup tests, drill stem tests, top and bottom of formation, gather core or fluid samples or other evaluations.

ATP

Advanced technology parts.

Buy back agreement

Agreement between a host and a contract lease holder under which the host pays the contractor an agreed price for all or part of the produced hydrocarbons.

AWGRS

Alaska well's group reporting system.

ALG

Algerian.

Drill string

All the equipment in a drilling BHA plus the drill pipe.

Face seal

Allowing a flat, usually polished, face to deform an elastomer and create a seal.

Alum

Aluminum and potassium sulfate compound. Used in water clarifying.

ACS

American Chemical Society.

AGA

American Gas Association.

AIME

American Institute of Mining, Metallurgical and Petroleum Engineers.

AIPG

American Institute of Professional Geologists.

ANSI

American National Standards Institute.

API

American Petroleum Institute.

ASME

American Society of Mechanical Engineers.

ASTM

American Society of Testing Materials.

Amines

Ammonia based materials (NH3), in which one of more of the hydrogen atoms are replaced by hydrocarbons.

Elbow

An "L" shaped fitting in surface piping.

Contingency string

An "extra" string in a casing design that can be used in the event of failure to get an upper string to the correct depth.

Bound fluid log

An NMR log that measures bound fluid volume.

Blast joint

An abrasion and erosion resistant tube that is run where ever direct sand impingement is a problem.

Adaptor spool

An adaptor that allows BOP's to be connected to wellhead flanges of various sizes.

Cement accelerator

An additive such as calcium chloride, and salt in high concentrations that speeds the set of cement.

Chronstratigraphic

An adjective meaning "time layer" (chrono=time, strata=layer). Interpreters must define the context in which they are using the term "time" (i.e., geologic time or seismic image time).

Electromagnetic Imaging devices

Field instruments which sense the ability of the local surroundings, including soil, to conduct electricity by detecting resistance to induced electromagnetic radiation. Used to sense variations in soil EC within a field, but also responds to soil water content, porosity, type and amount of clay, electric power lines, and buried pipes.

Cake

Filter or mud cake, stranded by dehydration on the face of a permeable formation by fluid loss.

External filter cake

Filtration control established on the surface of the wellbore by particles large enough to bridge on the entry of the pores.

Class C

Finer grind cement, higher early strength.

Corrosion film

First products of corrosion films that may form a tight, barrier film and reduce further corrosion.

Flying leads

Flexible hydraulic hoses connected to control systems in a subsea tree.

Crossflow

Flow between formations via a connected wellbore. Crossflow, as seen by downhole cameras, can occur with the wellbore full of fluid and the appearance of a dead well at surface.

Flow regime

Flow condition (e.g., mist, slug, churn, etc.) of a multiphase process stream.

Flowback

Flowing a well back after a treatment.

Belching

Flowing slugs of material.

Dean number

Fluid flow effects in spooled tubing.

Fracture porosity

he porosity attributed to the natural fractures, commonly less than 2 to 4%.

Gas hydrate

Immense deposits of natural gas tied up in clathrate structures with water. Found extensively. See also hydrate.

Cathodic protection

Impressed current that offsets the current produced in a corrosion cell and reduces corrosion.

Euler's method

In a seismic context, euler method is a profile or map-based depth estimation method based on a concept that magnetic fields of structures are homogeneous functions of depth and location. This is used to satisfy Euler's equation.

Absorption oil

In the context of facilities, this is the wash oil used to remove heavier hydrocarbons from the gas stream.

Accelerator

In a chemical context, these are chemicals that speeds up the rate of a chemical reaction. Most common are the accelerators used in cementing. In a drilling context, these are an energy increasing device, with sudden energy release, used in a jarring string while fishing.

Aromatics

In a chemical context, this term describes members of a family of chemicals with a ring structure of carbon chains. Normally xylene, toluene, etc. Benzene is an aromatic but is not used.

BRT

In a drilling context, BRT stands for below rotary table.

Bc

In a drilling context, Bc is Bearden units of consistency.

C/K

In a drilling context, C/K is choke and kill line.

Company zone

In a drilling context, a company man is the operating company representative on location.

Finger board

In a drilling context, a finger board is steel fingers mounted to the derrick into which the derrick man stores pipe that is standing in the derrick.

Clean circulation

In a drilling context, clean circulation is when fluids return to the surface without cuttings or other solids removed from the well.

Beta rating

In the context of filtration, this is a conditional ratio requirement on a filtering system that compares the number of particles of a certain size in the unfiltered and filtered fluid.

Broaching

In the context of fluid flow, broaching is the venting of fluids to surface through channels in cement or behind pipe (well control barrier failure) or unintended fracturing into a adjacent formation.

Beta factor

In the context of fluid flow, this is a correction factor for the Darcy Equation to account for changes in pressure and fluid saturation along a fracture.

Battery

In the context of fluid treating, batteries are the separation facilities.

Fracture conductivity

In the context of fracture flow, conductivity is the permeability of the pack times its width. Expressed in md-ft.

Decompression damage

In the context of gas effects on seals, decompression damage occurs when pressure is dropped rapidly, gas that has permeated the elastomers and some plastics may rupture the surface of a material when the gas expansion caused by the decompression is faster than the gas can pass through the substance. Most severe in weak tensile-strength materials.

Crossover

In the context of gravel packing, a crossover is a section of the treating string that transfers incoming flow from inside the pipe to the annulus below the crossover, and the return flow from inside the tubing to the annulus above the crossover. Straddles a packer.

Beta wave

In the context of gravel packing, this is the returning wave of gravel after the alpha wave when packing a well over about 55&deg deviation.

Anti agglomerants

In the context of hydrate control, these are chemicals which prevent hydrate crystals from sticking together and forming a larger mass.

Area of influence

In the context of wells, this term describes the area surrounding a well within which drawdown and production has changed the saturation and energy of the system.

Extensive properties

In thermodynamics and phase behavior, extensive properties depend on the amount of the phases (e.g., total volume and moles of liquid).

Fugacity

In thermodynamics, fugacity is a property of a gas, related to its partial pressure, that expresses its tendency to escape or expand. Also called: escaping tendency.

Amplitude

In vibration theory, this term describes the difference between the maximum or minimum values of a sinusoidally varying quantity and its mean. A wave's crest is its maximum amplitude, and the trough is its minimum amplitude.

Brackish water

Indefinite term meaning water with small amounts of salt. Saltier than fresh water.

Feed in

Influx into the well bore.

Core analysis

Lab work on a core sample that may yield permeability, porosity, pore size distribution, grain size, density, etc.

Geopressured

Overpresured zone.

Anodizing

Oxide coating of a metal surface to reduce corrosion.

Bit whirl

In a drilling context, this term describe the motion that a bit makes when it does not rotate about its center. This may manifest itself in out of round holes and severe bit damage. Generally a poor drilling performance.

Bit weight

In a drilling context, this term describes the applied downhole axial force component from the string weight.

Brake

In a drillng context, this is the main device for stopping the travel of the drawworks of a rig when running or pulling a drill string.

Cherry picker

In a fishing context, a cherry picker is an overshot fishing tool with a bottom cutter surface to allow milling the top slips or all the slips prior to retrieving a packer.

Check shot survey

In a seismic context, a check shot survery determines formation seismic wave velocities over specific intervals. Measurement is made of travel time from surface to downhole geophones.

Bullheading

Forcing fluids in the pipe into the formation at a pressure higher than the pore pressure and sometimes higher than the fracturing breakdown pressure. Used to displace a kick out of the pipe when wellbore and wellhead pressure limits permits.Wells with short open hole sections and zones of high permeability respond better to bullheading than wells with long open hole sections and low permeability zones.

Bo

Formation oil volume factor.

Acoustic base

Formations below the deepest zones that can be imaged by an acoustic process.

Autochtonous

Formations that formed in the present locations and have not been transported.

Allochtonous

Formations transported by fault or similar earth shift movements.

Coagulation

Forming a larger mass from smaller ones by collision and sticking together.

Agglomeration

Forming larger droplets, bubbles, or particles from smaller droplets, bubbles, or particles.

Breccia

Fragmented (not wear rounded) grains. Rock along moving faults may have this texture.

Free point and backoff

Free Point analysis followed by downhole unscrewing of a pipe coupling above the stuck point.

Blowby

Free gas separating from the liquid at the bottom of the separator. Generally indicates poor separator performance.

Bottomhole gas separator

Gas anchor or a separator used in front of a pump to deflect most of the free gas to improve downhole pump efficiency.

Entrained gas

Gas dispersed in a produced fluid.

Gas coning

Gas from a fee gas cap that goes downward toward the top perforations in response to a drawdown.

Free gas

Gas that is not dissolved in the liquid.

Cycle gas

Gas that is separated and reinjected

Blue gas

Gas volume that separates from produced water.

Cutter (cut-off tool)

Generally a reference to a device that severs the pipe downhole by explosive, chemical, heat or mechanical action.

Capillary pressure

Pressure differential between two immiscible fluid phases occupying the same pores caused by interfacial tension between the two phases that must be overcome to initiate flow.

Annular pressure

Pressure in an annular area. May be a vented or trapped annuli.

Casing -annular pressure

Pressure in the annulus between the tubing O.D. and the casing I.D.

Gauge pressure

Pressure read by a gauge that is set to zero at atmospheric pressure.

Choke trim

Pressure-controlling choke components, usually replaceable, expendable pieces.

Flexing

Pressuring and depressuring the tubing (ballooning) to remove plugs or knock scale and other debris loose from the tubing wall.

Anion exchange

Process where a special resin exchanges chloride or hydroxide for contaminant anions such as fluoride, nitrate, sulfate and bicarbonate. Water purification is the primary use.

Cogeneration

Production of electrical or mechanical energy and heat or other power.

Cummulative production

Production of hydrocarbon to date.

Domestic production

Production originating inside a specific country of reference.

Embedment

Proppant that has partly or completely sunk into a formation through displacement of the formation around the grain.

Entitlement

Reserves consistent with the cost recovery plus profit hydrocarbons that are recoverable under the terms of the contract or lease are typically reported by the upstream contractor (SPE).

Compartentalization

Separate compartments or smaller reservoirs in a larger, common reservoir that may not be in communication.

Break an emulsion

Separate the emulsion into its components.

Dewatering

Separation of liquids and solids in the general sense. Also removing water from hydrocarbon streams.

Composite log

Several logs spliced or overlayed to form a single group log record.

Armor

Shielding over a cable or other device that needs to be protected from crushing.

Diatomaceous earth

Silica particles from Diatom beds. Used as a filtering media and as an additive to cement.

Agate

Siliceous rock with alternating bands of chalcedony and colored chert.

Adsorption

The attraction and holding of a layer of a chemical on the wall of a formation. Usually held by ionic charge or wetting preference.

Elevator bails

The bars that attach the elevators to the hook on the traveling block. Also called elevator links.

Fairway

The best part of a reservoir. Commonly used in coal pays.

Geochemistry

The branch of chemistry dealing with the specialized reactions of downhole fluids and formations.

Carrying capacity

The capacity of an injected or circulated fluid to transport a given sized and density solid into a zone or from a well.

Acid effect

The change in pulsed neutron capture created by acidizing a carbonate. Acidizing increases interconnected porosity and strands chlorides and other ions in the rock.

Gas oil contact

The changing contact of the gas cap and the oil below in the rock.

Air gap

The clearance between the highest water surface that occurs during the extreme environmental conditions and the underside of the deck.

Accuracy

The closeness of agreement between the measure value and the exact value.

Collapse rating

The collapse pressure derated by a safety factor. Takes into account the effects of axial load. The formulas are only good for round pipe.

Assemblage

The collection of minerals that characterize a rock or facies.

Coalescence

The combination of bubbles or droplets in an emulsion to form larger bubbles or drops that will separate easier.

Drilling hook & swivel

The components below the traveling block to which the elevators are attached.

Critical buckling load

The compression load that initiates buckling in the pipe.

Cross-correlation

The computation of a spatial cross-covariance model between two regionalized variables. This provides a measure of spatial correlation between the two variables.

Absolute open flow

The maximum rate that a well can produce at the lowest possible bottom hole pressure (usually figured with a gas gradient). Typically abbreviated as AOF.

Allowable working pressure

The maximum stress allowed by code or other agreement or study as a fraction of test pressure. Design pressure of the system is related to hoop stress.

Endurance limit

The maximum stress that a material can withstand for an infinitely large number of cycles (NACE).

Fatigue strength

The maximum stress that can be sustained for a specified number of cycles without failure.

Cricondentherm

The maximum temperature for the formation of two phases (e.g., liquid and vapor) at a given pressure in a reservoir.

Absolute viscosity/ dynamic viscosity

The measure of a fluid's ability to resist flow without regards to its density. It is defined as a fluid's kinematic viscosity multiplied by its density.

Annular seal assembly

The mechanism that provides pressure isolation between each casing hanger and the wellhead housing.

Abandonment pressure

The minimum pressure of the reservoir when the wells are abandoned.

Basalt

The most common volcanic rock. Usually fine grained.

Coning

The movement of a water upwards or gas downwards towards a decrease in pressure caused by producing hydrocarbons in a zone with no vertical permeability boundaries.

Gravity drainage

The movements in a reservoir driven by gravity.

Connate water

The natural brine occupying the pore spaces. Usually this water is at equilibrium with the minerals in the formation.

Associated gas

The natural gas which occurs with crude oil. It may be free or dissolved. When it occurs as free gas, it may be called unassociated gas.

Activation logging

The near formation is irradiated with neutrons that transform some nuclei into radioisotopes. The isotopes produced can be detected by radioactivity energy levels and decay-time. The original elements can then be identified.

Casing weight

The nominal weight per foot of the casing. Heavier weight casings of the same size are necessarily smaller I.D.

FVF

The number of barrels of reservoir oil that shrinks to one stock tank (surface) barrel after gas breakout and light end vaporization. Abbreviated FVF.

Gas oil ratio

The number of standard cubic feet of gas contained in a barrel of oil.

Albian

The oldest terrain from the Cretaceous period.

Depth of investigation

The outer limit to which a logging tool can measure properties with a give accuracy.

External phase

The outside or continuous phase of an emulsion.

Condensate

The part of the hydrocarbon stream that is a vapor in the formation and condenses to a liquid after being cooled. Normally the volatile condensate has a composition of C5 to C8 and an API gravity of >40.

Completion interval

The pay zone exposed to the wellbore. This may or may not be the entire pay.

Acid solubility

The percent by weight loss of exposing a sample of material to an excess of acid.

Absolute porosity

The percentage of the total bulk volume that is pore spaces, voids or fractures.

Effective permeability

The permeability of the formation matrix to a particular fluid when two or more phases are present.

Fault plane

The plane or direction along which fault movement has occurred.

Crown plugs

The plugs above the flow T in a subsea wellhead.

Cementation exponent

The porosity exponent, m, in the Archie Factor.

Diagenetic porosity

The porosity formed by chemical and bacterial modification after the initial sediments were laid down.

Far field

The portion of a seismic propagation medium that is a distance of at least 3 or 4 wavelengths away from a source station.

Anode

The positively charged site in a cell. Oxidation site. The site of metal loss in corrosion.

downstroke

The recovery stoke downward on a beam pump where the pump is filling with fluid by pushing the open traveling valve through the standing fluid.

API density

The relative density of a hydrocarbon based on a scale of degrees API. Density in g/cc = (141.5 / (131.5 +API).

Desorption

The release of materials that have been absorbed or adsorbed in or onto a formation.

Cushion gas

The reservoir pressure necessary to keep gas recoverable.

Friction

The resistance to an object's passage through a fluid (or a fluid's passage past a stationary object). Affected by viscous resistance, density, wall contact (vessel radii).

Complex seismic trace

The result of applying a Hilbert transform to a seismic trace. A complex seismic trace consists of a real part (the input seismic trace) and an imaginary part produced by the Hilbert transform. The reason for transforming seismic data from the "real" domain to the "complex" domain is that reflection amplitude, phase, and frequency can then be calculated at each time sample point of the seismic wiggle trace.

Drill bit

The rock cutting device at the bottom of the drill string.

Counter weights

The rotating weights on a beam lift pump jack that offset the weight of the rod string.

Critical saturation

The saturation of a fluid at which the fluid will begin to flow as saturation is increased.

Geophysics

The science of the physical properties of the earth.

Geology

The science that deals with the study of the planet earth.

Bottom casing packoff

The seal in the annulus between a hanging pipe and the next pipe outward.

Bonnet

The section of the valve housing that covers the stem and protects the seals.

Dissociation

The separation of a compound or molecule into pieces, ions, or atoms.

Continental margin

The separation of emerging continents from deep sea basins.

Crown block

The set of pulleys or sheaves at the top of the mast on a rig.

Casing seat

The set point of the end of casing. Should be in an impermeable, stable formation.

Continental shelf

The shallow area out from shore to a water depth of about 450.

Foot wall

The side of the fault that protrudes underneath the upper formation.

Covariance

The sill minus the variogram model (or zero minus the correlogram). The kriging system uses covariance, rather than the variogram or correlogram values, to determine the kriging weights λ.

Biphasic

The simultaneous flow of two immiscible fluids.

Decline curve

The slope of the production rate vs. cumulative time or volume measurement. The decline of a well predicts how fast it is being depleted.

Creep

The slow movement of a solid due to an applied stress. Often very sensitive to time and rate of stress application.

Drill cuttings

The small chips and fines generated by drilling through a formation with a drill bit. Most of the cuttings are removed from the mud as the fluid pass through the solids control equipment (e.g., shakers, screens, cyclones, etc.,) at the surface.

Elevators

The snap-around latches that couple around tubing below the pipe coupling and enables the traveling block on a rig to grab and lift the tubular string.

BS&W

The solids and water entrained in crude oil. Abbreviated BS&W or BSW.

Dissolved gas

The solution gas associated with produced fluids.

Field rules

The spacing and production rules in a field or unit.

Base Fluid

The starting fluid for a pill or a treatment. Before additives.

Cement bond

The strength and adherence of the cement to the pipe and the formation.

Gas injection

The technique of injecting gas into a reservoir. It may be done for pressure maintenance, oil viscosity reduction, light end stripping or storage.

Critical temperature

The temperature above which a fluid cannot be liquefied by increasing pressure.

Curie point

The temperature above which a mineral loses its magnetism.

Dew point

The temperature at which liquids begin to condense from the vapor phase in a gas stream. (see also bubble point).

Crystallization temperature

The temperature at which the first crystal of salt appears from a brine that is being cooled.

Boiling point

The temperature at which the vapor pressure of the liquid is equal to the pressure exerted on it by the surrounding atmosphere.

Ambient temperature

The temperature of the surroundings, usually an average surface temperature or test surface temperature.

Elasticity

The tendency of a body to return to its original shape and size once the stress is removed.

Formation sensitivity

The tendency of a formation to react with fluids, usually filtrates from injected fluids.

Dual completion

Two pay zones in the same well that produce up independent flow paths in the same well.

Double Block and Bleed

Two successive plugs, each capable of holding maximum pressure, with a vent between them capable of bleeding off all pressure between the plugs. Also - a valve with two seating surfaces which, in the closed position, blocks flow from both valve ends when the cavity between the seating surfaces is vented through a bleed connection on the body cavity. Commonly written DB&B.

Casing joint

Typically a length of casing with a connection on each end. Length may vary from less than 30 ft (9 m) to about 40 ft (12 m).

Abandon

Typically means to cease efforts, either temporarily or permanently, to produce a well.

Drill stem

Typically, rotating components in a drill string.

Green cement

Uncured cement.

Basement rocks

Unproductive rocks, usually igneous or metamorphic, at the bottom of a sedimentary rock sequence.

Breakout

Unscrewing a joint of pipe of part of a BHA.

Attenuation

When a form of energy is propagated through a medium, its amplitude (energy level) is decreased. This term describe this decrease in energy

Failure

When the designed function can not longer be met.

Disaggregation

When the formation breaks into grains.

Economic limit

When the revenue from the produced fluids falls below the cost of operations set by the company.

Ball out

When using ball sealers, to effectively shut-off the entire zone and cause pressure to rise sharply.

Coiled tubing drilling

Where CT is used as the primary drill string with a mud (less commonly an electric) motor to rotate the bit. Often used in underbalanced drilling.

Diagenetic trap

Where rock changes produces a reservoir rock under a sealing rock.

Fault

Where rock splits or ruptures with associated movement occurs on either side.

Back off

Unscrewing a tool or equipment. In pipe recovery, back-off of a joint precedes recovery of the upper section in a well. Common in plug and abandonment or sidetrack operations.

Anomalous

Unusual data or measurement that is away from or out of the range of other data.

Acidizing

Use of a mineral acid (typically HCl or HCl/HF) or an organic acid (typically acetic or formic) to remove damage or stimulate the permeability of a formation.

Abrasion

Wearing away by friction.

Expandable casing

Well construction tubulars run in like conventional casing but mechanically enlarged downhole before the cement is set. Used mostly as drilling liners to isolate unstable intervals.

Expandable completion

Wellbore tubulars run in like conventional completions but mechanically enlarged downhole once in place. Can include combinations of sand screens, blank pipe and annular isolation seals used in lieu of gravel packs.

Development/ appraisal well

Wells that are drilled after the discovery and appraisal wells to develop the hydrocarbon production potential of the field.

Crown lands

Government owned land.

Gravity specific

Gravity of a fluid expressed as a ratio of a standard fluid. For liquids, the standard is fresh water. For gases, the standard is air.

Bomb hanger

Hanger for bottom-hole pressure recorder (bombs).

Bimodal

Having two modes, a property ascribed to certain histograms or probability density functions.

After cooler

Heat exchangers for cooling gas after compression.

Convective heat transfer

Heat transfer by gas, steam or liquid circulation. Heat transport by moving particles and the thermal energy they carry to a new location.

Conduction heat transfer

Heat transfer when two solids are in contact and heat passes between them -- heat transport by direct transfer of energy from one particle to another.

Amorphous

Without crystal form.

Carburizing

Heat-treating process where carbon is introduced into a solid iron alloy by heating above transformation temperature range while in contact with a carbonaceous material (solid, liquid, or gas form of carbon). Usually quenched to produce a hardened outer shell.

Class E & F

High temperature cements.

Drawworks

Hoisting mechanism on a drilling rig.

Deferred production

Hydrocarbon production that is delayed due to any of several reasons, specifically well repairs, restrictions that curtail production, regulations, etc.

Flow efficiency

Ideal drawdown / actual drawdown.

Casing cladding

Expanding pipe installed in production casing or tubing to seal perforation holes or leaks caused by corrosion or erosion. Can be metal or plastic.

Detonating cord

Explosive wrapped with elastomer in the shape of a cord. Used to link and detonate charges in perforating guns.

Collapse pressure

External hydrostatic pressure that will cause the onset of pipe yielding. Heavily influenced by tension loads on the pipe.

Critical failure

Failure of an equipment unit that causes and immediate cessation of the ability to perform its required function.

Corrosion fatigue

Fatigue-type cracking of metal caused by repeated stresses in a corrosive environment.

Gradiometer

In a seismic context, a gradiometer is a device that measures an electric field at multiple points at the same time. The gradient is the difference in measured values per unit of distance between the measuring points.

Gravity unit

In a seismic context, a gravity unit is an acceleration unit (gu) used in gravity measurement. 1 milligal = 10 gu.

Deconvolution

In a seismic context, deconvolution is an automated profile-based depth estimation method derived from analysis of magnetic anomalies in sheet-like bodies. Polynomials can be simultaneously solved to estimate the depth, dip, horizontal location and susceptibility (magnetic) of the surface or structure. Basically undoing the effects of a filter. (Using Werner)

Density contrast

In a seismic context, density contrast is the density of one rock relative to another. The contrast can be positive or negative. Gravity anomalies within sedimentary sections can be analyzed as structural or lithologic anomalies.

Depth migration

In a seismic context, depth migration is the data processing used to shift subsurface signals to their proper depth.

Gaging nipple

small opening in the top of a tank, allowing gaging of the contents.

Accumulator precharge

the initial nitrogen charge on a BOP accumulator that is placed before the fluid is pumped in to charge the accumulator.

Astenosphere

The weak section of soft rock in the upper mantle just below the lithosphere. It is involved in plate movement. Depth is 70 to 100 km below the surface.

Air weight

The weight of a string in air without the effect of buoyancy provided by wellbore fluids.

Buoyed weight

The weight of a string or piece of equipment immersed in the wellbore fluid. It is strongly dependent of the density of the wellbore fluid.

Flash

The weld seam on or in a welded pipe.

Fracture width

The width of a fracture at the wellbore. Hydraulic frac width is generated by frac fluid viscosity and/or pump rate (i.e., horsepower).

Drilling line

The wire rope used to position tools on the floor. Also used to describe the wire rope on a cable tool rig.

Conveyance

The wireline, slickline, tubing or coiled tubing used to convey tools or equipment in a well.

Backreaming

This is the practice of pumping and rotating the drillstring while simultaneously pulling out of the hole. When reliable topdrive drilling systems (TDSs) on conventional drilling rigs were introduced more than 25 years ago, the practice of backreaming became a popular technique in the driller's toolbox for tripping out of hole initially in deviated wells.

Common carrier

Those engaged in the transport of petroleum products.

Galling

Thread damage from lack of lubrication or mismatched metals.

Flocculate

To aggregate or clump together individual tiny soil particles, especially fine clay, into small groups or granules. The opposite of deflocculate or disperse.

Crack open the valve

To barely open a valve.

Correlate

To compare logging and core or other information and account for discrepancies.

Absorb

To fill part or all of the pore spaces.

Acid fracture

To fracture stimulate a formation by injecting the acid over the parting pressure of the rock and using the acid to etch channels in the fracture face

Burn over

To mill a piece of equipment (and often to catch it with an overshot).

Antiwhirl bit

A drill bit that, by its cutter placement, causes the bit to be forced against the side of the hole.

Cast iron bridge plug

A drillable plug that can be quickly and reliable set to isolate a section of the well.

Gauge hole

A drilled hole with no washouts; the same diameter as the bit.

Clay extender

A drilling additive to increase the viscosity of water based muds gelled with bentonite.

Choke line

A drilling and workover pressure control device. A line that attached to the BOP stack and through which kick fluids can be circulated when the BOP is closed.

Compaction drive

A drive mechanism in a weak zone that displaces fluid by reducing the overall volume of the formation.

Duster

A dry hole.

Emulsifier

A emulsion stabilizing mechanism, usually either surface active agent, fines, viscosity and/or charge.

Antrachite

A high grade coal.

AFLASTM

A high temperature seal elastomer.

Conductive concrete

A highly conductive cement and coke based material used an impressed current anode.

Fast line

End of a braided drilling line affixed to the draw works.

Blind nipple

Nipple that can be blocked off from formation pressure and give a false pressure measurement.

Dynamic flow

Non steady state flow or flow with changing conditions.

Elastic

Non-permanent structural deformation during which the amount of deformation (strain) is proportional to the applied stress (load).

Aliphatic

Nonaromatic (chemical).

Gasoline

Normally C7-C10 fuel, with a flash point of -40.

Fracture effective length

Normally the propped part of the fracture that will support improved flow.

Empirical

Observed response, often well proven by experiences but not theoretically derived.

Glass disk

Often a rupture disk to allow a well to flow after it is broken by a dropped bar.

Deep marine chalks

Often massive deposits of coccolith fragments. Usually very high porosity and limited permeability unless fractured.

Associated reservoir

Oil and gas reservoir with a gas cap. Gas production from these reservoirs may be restricted in order to preserve the gas cap energy and ultimate recovery.

Clean oil

Oil with less than 1% water. Usually within pipeline spec.

Class G & H

Oilfield related cements.

Bull wheel

Old term for a large, often wooden wheel, in a cable tool rig.

Acre-ft

One acre (43560 ft2) to a depth of one foot.

Density log

One of a number of logging techniques that estimate the density of the formation.

Casing centralizer

One of several centralizer designs intended to keep the casing better centered in the borehole to get better cement jobs.

Formate

One of several low damage, low toxicity, normally high cost brine for special applications. May be one of several formation compounds.

Foam breaker

One of several materials that reduce the stability of the bubble skin in a foam and cause the foam to break.

Chemical flooding

One of several methods involving injecting a chemical into a formation to improve the production of hydrocarbon. May be from an injection well to a production well or injection into a producer with a soak period before recovery.

Alarm point

Preset value of a monitored parameter at which an alarm is actuated to warn of a condition that requires corrective action.

Casing pressure

Pressure (intended or not) that occurs on the various outside annuli.

Expectancy

Remaining life.

Downhole separation

Removal of a part of the water downhole followed by injection of the water into a disposal zone.

Deliquification

Removal of condensed or produced fluids from a low rate gas well.

Cleanout

Removal of fluids or solids from a well, usually by circulating.

Desalination

Removal of salts from saline soil, usually by leaching.

Bail

Remove solids or fluids from a well.

Blowdown

To release gas pressure. In a reservoir, blow down is often after the oil recovery phase has been complete and the majority of the gas from the gas cap needs to be recovered.

Dress-off

To remove rough edges, flares, burrs, etc. from a piece of equipment prior to fishing.

Dress

To sharpen a bit or replace components of a tool.

Buck up

To tighten a connection.

Bleed off

To vent or drain of fluids from a pressured well.

Gross production

Total production. Has been used as total fluids produced. Has also been used as cumulative hydrocarbon production.Total production. Has been used as total fluids produced. Has also been used as cumulative hydrocarbon production.

APR

Trademarked name for an annular pressure response valve for a DST string.

Flow tubes

Tubes with a diameter slightly larger than the braded wireline or slick line that are used in the "stuffing box" on a wireline intervention to isolate the well pressure and fluid from the atmosphere. They work in combination with oil or wireline grease injection to form a hydraulic seal.

Bound water

Water that is trapped in or on the matrix minerals and cannot move.

Gas lock

"In the context of facilities, a gas lock is a gas retention device that permits gauging the tank without loosing gas to the atmosphere.

Crest

"In the context of fluid flow, a crest is the top of the water cone in (usually) a horizontal well. Compare with coning in a vertical well.

Grain

"In the context of fluid loss additives, grain is literally grain or animal feed that is circulated with mud to act as a identifiable marker.

Diversion

"In the context of fluid treating, diversion is a method of limiting the fluid entry into a higher permeability zone and causing the fluid to flow to a lower permeability zone.

Drag

"In the context of fluidflow, drag is the force on a solid surface exerted by a fluid flowing past it.

Balance point

"In the context of forces on a pipe, this term describes the point at which forces acting on pipe in a well (usually while running) are equal.

BLM

"In the context of leases, BLM stands for US Bureau of Land Management.

Area to volume ratio

"In the context of minerals, this is the ratio of the area of the surface of a grain to its physical volume.

BH

"In the context of perforating, BH abbreviates big hole charge.

Coating holiday

A break in an otherwise continuous coating.

Composite bridge plug

A bridge plug made mainly of plastic and composite materials.

Dry gas

"In the context of production, dry gas is a gas stream without condensate. Note: even dry gas at bottom hole conditions may have up to two barrels of water vapor per million standard cubic ft of gas. Dry gas on the process side has all liquids removed.

Air gun

"Seismic source for ocean seismic work.

Compatible brine

A brine that does not create formation damage or permeability reduction when introduced into a formation.

Clear brine

A brine without suspended solids.

Dump bailer

A hollow tube with a flapper or other opening valve at the bottom, run on wireline to place cement or sand in a well.

Authigenic

A clay or other mineral that was formed within the pore spaces of the rock. The material is most often formed by reaction or precipitation from connate fluids.

Duplex steel

A corrosion resistant alloy with chrome and nickel as common components.

Female connection (box)

A coupling with threads on the inside.

Dog house

A crew or records shack at a lease or on a rig.

Bailer

A hollow tube with a trap door or ball seat, run on wireline, which can be used to spot or remove solid material from a well bore.

Displacement

"In the context of a horizontal well, displacement is the distance between the wellhead and the top of a vertical line from the bottom hole location to the wellhead elevation at the surface.

Drift

"In the context of a pipe gauge, drift is the minimum id of tubing through which a standard drift tool will pass.

Diverter

"In the context of acidizing, a diverter is a material that forces acid to enter another zone by having a higher viscosity or building a filter cake.

Flow assisted corrosion (erosion-corrosion)

Corrosion that is accelerated by the effects of erosion removing the initial corrosion films.

Critical flow rate

"In the context of corrosion or errosion, critical flow rate is the maximum flow rate that avoids damage to the pipe from corrosion or erosion.

BOD

"In the context of design, BOD stands for basis of design.

Ballooning

"In the context of drilling, ballooning is the phenomenon in which fluids are lost to the rock during over-pressured operations, such as found in increased pressures from equivalent circulating density operations, and then flow back when pressure is reduced. This may be confused with a kick.

Blistering

"In the context of elastomers, blistering is surface deterioration caused by gas trying to escape too rapidly from a elastomer and tearing the surface of the material.

Critical frequency

A critical frequency is a frequency at which amplitudes become unbounded. This occurs when the frequency of the system matches one of the natural frequencies.

AFE

"In the context of expenses, AFE stands for Authority for Expenditure on a well (authorized funds for drilling or workover).

Borate

A crosslinker for guar based gels.

Arch

"A large, load supporting formation that may serve to reduce the total overburden load on a pay zone. These formations may cover hundreds of square miles over a basin.

Bright spot

"A specific seismic reflection that may indicate gas.

Aggregate

"Aggregate may refer to

Confined aquifer

"An aquifer bounded above and below by impermeable beds, such as clay or unfractured shale, or by beds of distinctly lower permeability than that of the aquifer itself.

Fragipan

"Dense layer of soil containing silt and sand, but no organic matter and little clay. May have extreme hardness due to compaction.

Anisotropy

"Differences in rock — segments showing different responses when measured. This is represented by covariance models that have major and minor ranges of different distances (correlation scale or lengths). There are two types of anisotropy: geometric anisotropic covariance models have the same sill but different ranges, whereas zonal anisotropic covariance models have the same correlation ranges, but different sills.

Gauge

"In a drilling context, a gauge is the diameter of the bit of the hole drilled by the bit when there are no washouts.

Cycle time

"In a drilling context, cycle time is the round trip time for a circulated fluid.

Accumulator

"In context of a pressure control device, these are canisters of hydraulic fluid, pressurized with a nitrogen gas cap of sufficient pressure and volume to operate all the rams on a BOP in case of power failure to the BOP.

Critical velocity

"In terms of erosion, critical velocity is the temperature above which a fluid cannot be liquefied by increasing pressure.

Bridle

"In the context of a beam lift, a bridle is the wire rope attachment of the horses head to the polish rod on a beam lift pump jack.

Erosion

"Wear of a material by a slurry of liquid and (usually) solids.

Eustatic

"Worldwide sea-level changes affecting all oceans. It is thought that eustatic sea-level changes can be linked to climatic changes and to eccentricities in the Earth's orbit.

Free water

"he excess water that separates from a cement slurry on standing.

Clay

1. A fine grain (<0.00015" or about 4 microns) -- finely crystalline silica sheet minerals. Usually of silicate composition. In oil field terms, the most common clays are Smectite (montmorillinite), illite, kaolinite and chlorite. The characteristic for authogenic clay is to have extremely high surface area-to-volume ratio.

Casing seat test

A LOT or a FIT test (check specifics for details), a pressurized test after primary cementing to make sure the bottom most seal with the formation will handle pressures needed for drilling the rest of the well.

Flush joint

A Non Upset connection in most cases.

Brent

A North Sea field with a light crude oil used for cost comparisons.

Cell spar

A Spar platform with multiple floatation sections

Bbl

A Standard Oil measure of 42 gallons, originally known as a blue barrel and abbreviated bbl. 0.16 m3

CERCLA

A US Law -- Comprehensive Environmental Response, Compensation and Liability Act of 1980.

Chevron packing

A V-shaped seal very common on moving and static seals.

Core barrel

A barrel in the drilling BHA with a coring head designed to receive a rock core cut as part of core sampling operations.

Fold

A bend-like disruption in a rock strata such that the angle of the formation is significantly changed.

Bicenter bit

A bit that, when rotated, drills a hole larger than its diameter.

Centralizer

A bladed or bow spring tool that helps center tools or pipe in the wellbore.

Detonator

A blasting cap.

Graben

A block of the formation that has slid downward between two faults.

Bridge

A blockage in the wellbore caused by a mass of particles that lock together and prevent pipe movement or flow.

Completion fluid

A brine, oil or gas based fluid that is used as isolation (kill, separation, inhibition functions, etc.) fluid during the completion of a well. Commonly sea water, NaCl brine, formation water, KCl brine, CaCl2 brine, etc. Oil based fluids are common where formation sensitivities with shales, clays, minerals, etc., prevent use of aqueous fluids.

Bed filtration

A build-up of particles on the upstream side of a filter that improves the filter's ability to remove particles from fluid (will also raise the differential pressure across the filter).

Flare

A burner on a remote line used for disposal of hydrocarbons during clean-up, emergency shut downs and for disposal of small volume waste streams of mixed gasses that cannot easily or safely be separated.

Butadiene

A butane derivative used in manufacture of synthetic rubber (elastomers).

Calcacerous

A calcium carbonate coating.

Caliche

A calcium rich surface soil.

Chlorine log

A cased hole log, using gamma ray capture by chlorine atoms, that helps estimate the salinity or water behind pipe.

Balanced plug

A cement plug, set with no downhole flow conditions, which allows temporary or permanent shut-off in a well. It takes into account the densities of all fluid columns, both in the string and in the annulus.

Foam cement

A cement slurry, foamed with between 40 and 60% nitrogen gas. Has a slurry density of about 7.5 to 10 lb/gal (0.9 to 1.2 g/cc).

Block squeezing

A cement squeeze into a area of perforations. Often done initially over the frac pressure.

Disconformity

A change in the formation that may have been caused by ancient erosional forces. Accounts for variances in formation tops in near-by offset wells in a formation with no pay inclination.

Cement channel

A channel in the cement, usually caused by poor displacement of drilling mud.

Breaker

A chemical added to a gel that breaks down the gellant structure.

Cement retarder

A chemical additive such as lignosulfonate, salt in low concentration or most muds that slow down the cement.

Demulsifier

A chemical additive, usually a surfactant, that helps break emulsions.

Emulsion stabilizer

A chemical or physical effect that prevents separation of two or more, normally immiscible phases. Normally surfactant, electrical charge, liquid or emulsion viscosity, or micron sized solids at the interface.

Biocides

A chemical or treatment that kills bacteria.

Benefication

A chemical process that changes the state of a clay or other mineral to make it meet specific performance levels.

Corrosion inhibitor

A chemical substance or combination of substances that, when present in the environment, prevents or reduces corrosion (NACE).

Curing agent

A chemical substance used to initiate the hardening reaction of a resin.

Chelant

A chemical that can tie up the molecules of an element, such as iron, and keep it in solution past the point where it should naturally precipitate.

Catalyst

A chemical that enables or speeds up a chemical reaction without being consumed by the reaction.

Buffer

A chemical used to keep the pH in a certain range without extremes of high or low pH.

Activator

A chemical, heat, radiation, or mechanical action that starts or accelerates a chemical reaction.

External cage choke

A choke capable of handling high solids content flow. The external sleeve is moved over a perforated hub with high erosion resistance properties.

Fishtail bit

A drag bit with no moving parts, rotated like a conventional metal drilling bit.

Chlorite

A clay type marked by high iron content. Usually not water sensitive and only slowly acid soluble. Very occasionally existing as fragile, free standing rims following sand grain dissolution over geologic time.

Cleat fracture

A cleat fracture in coal is a natural fracture along the cleat plane, usually parallel to max stress. Often extensive, especially in thin beds.

Gneiss

A coarse, metamorphic rock with some parallel alignment of granular minerals and alternate bands of flaky or elongate minerals.

Descriptive statistics

A collection of numbers, each called a statistic, such as mean, median, standard deviation, and skewness, that describes a set of data; also the process of calculating these numbers.

Bentonite

A colloidal clay, generates plastic viscosity due to their size and electrostatic layer.

Attapulgite clay

A colloidal, viscosity building clay used in water based muds. They generate viscosity due to the mechanical interference of their straw shaped bodies.

Expandable hanger

A combination hanger and packer run like conventional hangers for drilling liners and well completions but permanently mechanically expanded once in the well.

Benzoic acid flakes

A common diverter. It can sublime, or go directly from a solid to a gas.

Differential sticking

A common method of pipe sticking where the overbalance pressure in the wellbore pushes the tubing against the side of the wellbore in a permeable formation.

Fann viscometer

A common viscometer for oil-field fluids.

Common process

A common way of working that generates and/or protects value, sets out baseline expectations, to materially impact performance, is enduring and globally consistent, and helps advance the capacity of the global organization.

Clintoptolite

A common zeolite mineral with sensitivity to some surfactants.

Flange

A common, high pressure wellhead connection, using bolt attached flange plates and metal-to-metal seals.

Analogous reservoir

A comparable reservoir with many similar characteristics (e.g., lithology, depositional environment, porosity, perm, drive mechanism, produced fluids, etc.) that can be used for behavior projections comparison studies.

Cased and perforated (cased hole)

A completion technique where casing is cemented in the drilled hole and perforations are placed at the most promising flow points based on log interpretations.

Cavity completion

A completion that uses flow to purposely increase the size of the open hole wellbore.

Coiled tubing completion

A completion where CT and associated CT-mounted hardware is used as the primary completion flow path

Ancilliary component

A component (e.g., bend stiffeners and buoyancy modules) used to control flexible pipe behavior.

Bicarbonates

A compound containing the HCO3- ion.

Additives

A compound incorporated into a gas, liquid, or solid system to alter the properties for a particular purpose.

Geographic information system (GIS)

A computer database management system, which includes remote sensing, mapping, cartography, and photogrammetry for conducting spatial searches and making map overlays.

Farm-out

A concession owner selling a percentage of a lease to an outside operator for drilling a well.

Cellar

A concrete or culvert pipe walled section below ground that often protects and shelters the annular access valves. Also used to house the BOP's on a drilling well.

Blowout preventer

A conditional surface pressure barrier often consisting of a set of hydraulically operated rams containing equipment designed to grip pipe, seal around pipe, shear off pipe or seal an open hole during drilling or a workover. It may also contain an annular preventer.

Dimple connector

A connector with shallow holes into the body and threads on the other for attaching a BHA to coiled tubing. The end with shallow holes is slipped into the coiled tubing and a clamp-on device with set screws is used to deform the coiled tubing wall into the dimple.

Coiled tubing

A continuous reeled tube from 1 to over 3.5 inches in diameter. The tubing is injected into a well via a coiled tubing unit (CTU) and can be used to unload wells with liquid, foams or gasses, logging, fracturing, etc.

Casing string

A continuous string of casing, usually cemented over at least part of its length and usually extending back to surface from the set point.

Drill stem test

A controlled production of a small amount of fluid from an isolated section of the pay zone into the chamber formed by the drill pipe and a downhole valve. Drillstem tests measure pressures, some elements of depletion, and gather samples of the produced fluids. Abbreviated as DST.

Crude oil equivalent

A conversion of all gas forms to a comparison oil volume. Conversion factors are usually 5.6 to 6.0 mscf (depending on btu of the gas) to 1 bbl of oil.

Anticline

A convex-upward formation of rock layers a fold with the strata sloping down on the sides from a common crest. In association with a sealing rock, this may form a trap for hydrocarbons. These structures may be faulted or unfaulted. The majority of the hydrocarbons produced so far have been from anticlines.

AMPS

A copolymer. Acrylamido-methyl-propane sulfonate polymer.

Compaction

A crushing of the matrix structure as overburden loads press down on the rock, reducing the pore space. During production of the well, the load on the matrix increases as the pore-filling fluids are removed. These loads may reduce the porosity of the rock expelling fluids from the rocks (compaction recovery of fluids). Permeability may be decreased in compaction, first by closing natural (unpropped fractures) and then by reduction of matrix perm in severe cases.

Calchedony

A cryptocrystalline form of quartz with waxy luster.

Contour

A curve connecting points of equal value on a map.

Ball catcher

A cylinder at surface to catch ball sealers before the fluid is routed through the choke.

Dune

A deposit of sand produced by wind or running water. The dune may be massive, but usually lower energy and permeability varies.

Braided stream

A depositional environment with several channels that may or may not be connected.

Flooding surface

A depositional surface marking the transgression of a flooding event across an area. Deeper-water fauna occur above a flooding surface; shallower-water fauna exist below that surface.

Extrusive igneous rock

A description of rock resulting from a magma breach to surface and exposed to atmospheric conditions during cooling.

Expansion joint

A device in a length of pipe that allows some pipe length expansion or contraction.

Bottom shot detector

A device in a perforating gun that signals through a delayed shot or sound that the detonating cord has fired to the bottom of a gun.

Dampener

A device in the line filled with gas that may reduce the surges of pressure pulsation or flow slugging. Also spelled dampener.

Flow divider

A device on the entrance to a screen to route the incoming flow more evenly across the face of the screen.

Boot sub

A device run in the drill string just above the mill to catch cuttings.

Gas buster/ degasser

A device that helps knock out gas from circulated well fluid.

Ball dropper

A device that injected balls into the flowing treating fluid downstream of the high pressure pump.

Gravity meter

A device that measures gravity changes over a specific area.

Gravimeter

A device that measures the local gravitational pull. Gravimeters are useful for determining small changes in the gravity. Very useful for detecting salt domes.

Annular packoff

A device that seals the annulus to pressure or flow.

Cyclone

A device that separates cuttings by centrifugal motion of the fluids

Centrifuge

A device that separates materials by density through a centrifugal motion.

Eductor

A device that through flow of a power fluid through a nozzle, creates a low pressure area useful for moving fluids.

Densitometer

A device used for reading the density of a flowing fluid or slurry.

Basket sub

A device used to catch debris in the wellbore. Often a part of the string. Also known as basket sub.

Choke

A device used to create a controlled pressure drop and allow some expansion of the gas. A choke holds a back pressure on the well fluids, controlling the expansion rate of the gas. It is useful for optimizing natural gas lift in oil wells with sufficient gas to flow naturally or in some gas lifted wells.

Broach

A device used to reround slightly collapsed tubulars.

Chisel bit

A device with a single bit running the width of the hole. Also called a dove-tail bit.

Bird

A device with moveable vanes attached to an under water seismic streamer.

Consistometer

A device with rotating paddles, used to check the pumpability and set time of cement slurries.

Anchors

A device with slips that holds equipment in the wellbore.

Gas effect

A difference in porosities caused by the compressibility of gas in porosities estimated by the formation density log and the neutron density log.

Facies

A different part of the rock strata indicating a change in mineral content or deposition mechanics.

Colloidal suspension

A dispersion of fine particles, held by charge or other force in a stable suspension.

Formation

A distinct mapable layer

Era

A division of geologic time, next shorter than the eon and larger than a period.

Casing collar log

A downhole log recording, given by magnetic deflection, of the location of couplings or other equipment. Abbreviated CCL.

Annular safety valve

A downhole safety valve that shuts off the annulus. Abbreviated ASV.

Gauge carrier

A downhole tool that houses gauges.

Casing scrapper

A downhole tool with scraping teeth and brushes that is used to remove perforating burrs, lipped down areas in connection pins and remove mill scale, dried mud or cement, pipe dope and other well completion debris.

Casing roller

A downhole tool, commonly run on pipe to try to reform the casing after a partial collapse.

Compton-scattering

A gamma-ray reaction in which the gamma-ray, after colliding with an electron, shifts some energy to the electron. The higher the energy loss by Compton scattering in a zone, the higher the electron concentration or density. The basis for the density log.

Annubar

A gas flow rate measurement device using Pitot tubes. Common in pipelines.

Foam

A gas in liquid emulsion. Common as a low density cleanout fluid or a frac fluid with reduced water content.

Casing valve

A gas lift valve that is controlled by the casing or annulus gas supply pressure.

Gas anchor

A gas separation device, usually a perforated pipe section, in a beam lift well that helps break gas out of the liquids, preventing gas entry and resultant gas lock of the pump.

Damage

A general term commonly referring to an obstruction in the flow path

Exploration

A general term covering the search for oil and gas.

Coke

A generally insoluble hydrocarbon that has been oxidized to the point of a solid, often hard mass.

Casing grade

A generic grade classifying the strength of the pipe L80, P-110, etc. The numbers are the minimum yield of the steel in thousands of psi.

Cenozoic

A geologic epoch from today to 65 million years ago. Few major hydrocarbon bearing strata unless fluids have migrated to a trap from older source rocks.

Eocene

A geological epoch from 38 million to 55 million years.

Devonian

A geological time between 365 million and 405 million years ago.

Cambrian

A geological time from 500 million to 570 million years ago. Often signals the earliest hydrocarbon productive rocks.

Cretaceous

A geological time from 65 million to 140 million years ago.

External drift

A geostatistical linear-regression technique that uses a secondary regionalized variable (e.g., a seismic attribute) to control the shape of the final map created by kriging or simulation. External drift uses a spatial model of covariance.

Conditional simulation

A geostatistical method to create multiple equally probable images of a regionalized variable on the basis of a spatial model. It is conditional only when the actual control data are honored. Conditional simulation is a variation of conventional kriging or cokriging. By relaxing some of the kriging constraints (e.g., minimized square error), conditional simulation can reproduce the variance of the control data. The final "map" captures the heterogeneity and connectivity that most likely is present in the reservoir. Post-processing conditional simulation produces a measure of error (standard deviation) and other measures of uncertainty, such as isoprobability and uncertainty maps.

Detridal

A grain of a sedimentary formation that was transported from its origin and deposited as a whole grain in the matrix of the rock.

Consortium

A group of unrelated companies working on a specific venture.

Expendable gun

A gun made up of perforating charges linked together with wire or clips. The debris is not recovered on the wireline run.

Doughnut

A hanger, usually screwed onto the end of the top tubing joint and lowered into the slip bowl of the wellhead.

Chert

A hard, silicate sedimentary rock. Similar to flint, but with less ordered structure. A cryptocrystalline form of quartz.

Casing swage

A hardened steel tool, commonly run on wireline, which is used to reshape the casing. Also known as a casing broach.

Case hardened

A hardening process that hardens only the outer surface of a metal. Processes include carburizing, nitriding, flame hardening, etc.

Bit breaker

A heavy plate that can hold the bit in the rotary table to make or break it from the drill string.

Drill pipe

A heavy wall tubing used for drilling.

Basin

A large area with a general containment and an often thick accumulation of rock. A sedimentary basin is an area of regional settling that can be characterized in space, time, and sedimentary fill .It is a physical depression at the earth's surface which accumulates and preserves sediments. The scale of basins varies greatly, from ocean basins to small ponds.[1]

Dike

A large igneous intrusion that cuts through the sedimentary layers, creating permeability barriers.

Casing gun

A large perforating gun, run into a well without tubing.

Casing plunger

A larger plunger designed to lift fluids when flowing gas up casing without presence of tubing

Blind zone

A layer of rock that cannot be detected by seismic.

Casing liner

A length of casing that runs from a set point to a point part way up in the previously set casing string, but usually not to surface. A liner may be used instead of a full casing string to save money, to maintain a larger ID for well equipment or to prevent creating a trapped annular space.

Cheater

A length of pipe used on a wrench to extend the leverage. (HSE risk).

Continuous gas lift

A lift system that uses continuous injection of gas into the liquid column.

Coating

A liquid, liquefiable, or mastic composition that, after application to a surface, is converted into a solid protective, decorative or functional adherent film (NACE).

Division order

A list of interest owners and their share of revenues.

Distributed temperature log

A log of temperature along the entire length of the interval, well or flow path.

Dip meter

A log that measures the inclination of the formation beds.

Borehole compensated sonic

A log that measures the interval transit time for a compression wave to move a unit of distance, usually one foot.

Cross dipole

A log with the receivers located 90o to the emitter.

Fish

A lost piece of equipment in the well.

Carbon steel

A low alloy steel, containing a mass fraction maximum of 2% carbon, 1.65% manganese and residual quantities of other materials. Common in pipe manufacture.

Bow spring centralizer

A low to moderate strength centralizer formed by arched spring-like straps of metal.

Cessium formate

A lower toxicity (than Zinc) weighting agent for higher density brines.

Cessium acetate

A lower toxicity weighting agent for brine.

Fishing magnet

A magnet, usually run on wireline, used to recover lighter metal components from the well.

Collar log

A magnetic inflection log, run on wireline that is principally used to locate the depth of threaded pipe connections and other masses of metal.

Base Map

A map containing boundaries, locations and survey points.

Crosswell tomography

A map of the acoustic strata record between two wells where the emitter is in one well and the receiver is in the other.

Coccolith

A marine, single celled (1 to 5+ micron) animal that is a component of chalks.

Antifoamer

A material that can quickly destabilize foam in a production fluid treating facility. Commonly needed after treatment with foamers, diesel, some polymers, some acids and gasified fluids.

Dialectric

A material that does not conduct electricity or has only a low electrical conductivity compared to a metal.

Cement poison

A material that stops cement from setting.

Electrolytes

A material that, when dissolved in water, causes or increases the fluids' electrical conductivity.

Friction reducer

A material, usually a polymer that reduces the friction of flowing fluid in a conduit.

Brownfield

A mature field on decline or in the final stages of productive life.

Correlogram

A measure of spatial dependence (correlation) of a regionalized variable over some distance. The correlogram also can be calculated with an azimuthal preference.

Brinnell hardness

A measure of the hardness of the material, generally measured by pushing a small ball into the surface and measuring the force used to displace the ball to a set depth.

Blaine fineness

A measure of the particle size of a cement.

Fluid pressure gradient

A measurement in the well of the pressure vs. depth. Useful for spotting liquid levels, leaks, fluid entries, etc.

Fluid loss coefficient

A measurement of fluid loss expressed in cc/min1/2

Displacement efficiency

A measurement of how completely a flooding fluid displaces the saturated fluid in a reservoir.

Darcy

A measurement of permeability (ability of fluids to flow through the rock). The relationship is an empirical law which states that the velocity of flow through porous media is directly proportional to the hydraulic gradient, assuming that the flow is laminar and inertia can be neglected.

Formation resistivity

A measurement of the electrical resistivity of a formation. The measurement will be significantly affected by the type of fluid and the salinity of water based fluids within the pores of the rock.

Directional survey

A measurement of the well path that records the inclination and azimuth of the wellbore using a compass or other device.

Fracture fluid efficiency

A measurement, derived from a data frac, of the efficiency of a particular fluid in creating fracture area on a particular formation at a set of conditions.

Collett

A mechanical device used for holding or locking where segmented keys or fingers are pushed into a recess to hold, anchor or grasp the tool.

Coiled tubing connector

A mechanical device used to join strings of CT or attach a BHA to the CT.

Decentralizing arm

A mechanical level that pushes a tool against the side of the well.

External cutter

A mechanical, chemical or explosive device that is lowered over a pipe to cut from the outside.

Fatigue

A metal failure based on weakening by flexing or cycling. The material often work hardens.

BX-ring

A metal-to-metal seal for a flange.

Allocation method

A method of allocating volumes to affected parties when an imbalance occurs.

Extreme overbalance perforating

A method of applying a very high pressure surge to the formation at the instant of perforating. Usually in excess of 1.4 psi/ft. Designed to overcome frac initiation pressure and break down each perf with a very short (<1 m) frac.

Depreciation, straight line

A method of computing depreciation under which equal annual amounts are set aside for the ultimate retirement of the property at the end of its service life. For a property with an assumed 25-year life, the annual charge would be 4% per year, usually applied to the cost of the property less estimated net salvage (From AGA).

Barrel oil equivalent

A method of equating the energy produced by a hydrocarbon gas to a standard oil measurement. One barrel of oil has about the same heat producing capacity as 6,000 ft^3 of gas at standard conditions. Abbreviated BOE.

Constant choke pressure-kill

A method of killing a well where the choke is adjusted to maintain a constant casing pressure as the a water kick rises in the annulus. The method should not be used with a gas kick (will not keep a constant BHP).

Electric logging

A method of rock and fluid identification or evaluation that began in 1927. The first log was run by Conrad Schlumberger.

Fracturing

A method of stimulating production by increasing the permeability of the producing formation. Under extremely high hydraulic pressure, A fluid (as water, oil, alcohol, dilute hydrochloric acid, liquefied petroleum gas, or foam) is pumped downward through tubing or drill pipe and forced into the perforations in the casing. The fluid enters the formation and parts or fractures it. Sand grains, aluminum pellets, glass beads, or similar materials are carried in suspension by the fluid into the fractures. These are called propping agents or proppants. When the pressure is released at the surface, the fracturing fluid returns to the well, and the fractures partially close on the proppants, leaving channels for oil to flow through them to the well. This process is often called a frac job.

Dispersion

A mixture of an internal phase of solids, droplets or bubbles that stay relatively suspended in a continuous fluid.

Copolymer

A mixture of two or more polymers which polymerize at the same time and with some degree to linking to yield results unlike either polymer used alone.

Brine

A mixture of water and a soluble salt. Most common brines are sodium chloride NaCl, potassium chloride KCl and calcium chloride CaCl2. Brine densities may range from 8.33 to > 19 lb/gal (1 to >2.28 g/cc). The USGS definition of a brine is a salinity of more than 35,000 mg/L (after USGS, 1984).

Deterministic model

A model for which every input variable, and hence each output variable as well, is given exactly one value, in contrast to a probabilistic model.

Aluminium stearate

A mud degasser chemical.

Fall-off test

A multi-functional test that can be used to determine fracturing pressure or if the well is fractured.

Concentric completion

A multiple completion in which the upper zone flows to the surface through the annulus formed by the casing and the deeper zone tubing. Usually used only in sweet, dry gas upper completions.

Compression set packer

A retrievable packer where the slips are set and the seal energized by setting tubing string weight down on the packer. Releases by picking up the string. Useful where annular pressure could unseat a tension-set packer.

Alkyllation

A reverse cracking process that convents hydrocarbon light ends (olefins) into longer chain, liquid fuels.

Bingham plastic

A rheological model used to describe flow in some fluids. Bingham fluids have a linear shear stress, shear-rate behavior after an initial shear-stress boundary has been crossed. Plastic viscosity or PV is the slope of the line. Yield Point is the threshold.

Clastic

A rock grain, formed somewhere else and transported into place to be part of another rock.

Confining bed (seal)

A rock layer that through either low permeability or different modulus serves as a boundary for an event such as fluid flow or fracturing

Directional permeability

A rock with a higher permeability along a given plane, usually created by natural fracture development, water flow that leaches the pores, depositional environment or localized reworking of the sediments.

External casing packer

A rubber bladder over a section of casing that is inflated, usually with cement, to give an annular seal in open hole sections. Frequently used with liners and set at intervals along the open hole.

Elastomer

A rubber or plastic material used as a seal. May occur naturally or be synthesized.

Deadman system

A safety system designed to automatically shut in the wellbore in the event of a simultaneous absence of hydraulic supply and control of both subsea control pods.

Diapir

A salt or other column that pierces upper layers and may form traps of obstructions to flow.

Core

A sample of the formation, taken with a core barrel.

Gravel pack

A sand control completion that uses a larger gravel to stop the formation sand and a screen to stop the gravel.

Cased hole gravel pack

A sand control completion that uses a screen and a gravel pack to stop formation sand production.

Dry sieve method

A sand particle size distribution obtained by shaking a sample of sand through a series of sieves or screens.

Friable sands

A sand with an unconfined compressive strength of 300 to 1000 psi. Crushable with forceps.

Arkose

A sandstone containing 25% or more of feldspars, usually derived from silicic igneous rocks.

Granite wash

A sandstone with a large percent of weathered granite grains.

Graywhacke

A sandstone, characterized by angular-shaped grains of quartz and feldspar set in a matrix of fine grains. May have high hardness.

Flow assurance

A science field dealing with prevention of scales, hydrates, asphaltene and paraffin deposits and other problems that could stop flow of fluid from the subsurface, wellhead or pipeline.

Bull plug

A screw-in plug, normally used at the bottom of a string if no fluid entry is desired.

Gland

A seal around a moving rod.

Dynamic seal

A seal in a system where motion is expected in the seal or the seal area.

Fluorocarbon

A seal with good resistance to aromatic fluids but susceptible to sour gas.

Cap rock

A sealing formation of very low permeability that forms the top or the seal in a reservoir.

Anithic fault/ antitheic fault

A secondary fault, often in a set, with opposite direction to the primary fault.

Delineation well

A secondary well, after a field discovery well, drilled to help determine field extent, volume or potential rate.

Gas lift mandrel

A section of pipe used in the tubing into which a gas lift valve can be inserted. The mandrel will allow communication with the annulus gas lift supply through the valve.

Dead leg

A section of pipeline that is not in use.

Drilling spool

A section of the BOP that allows side ports for choke and kill lines.

Bowl

A section of the wellhead or of a tool what allows slips to be inserted to hold pipe or equipment.

Biostratigraphy

A segment of geoscience where fossils are used to date or identify a reservoir.

Body wave

A seismic wave that propagates in the interior (body) of the Earth. See surface wave.

Depth structure map

A seismic-derived map showing the geometry of subsurface structure in terms of depth coordinates. See time-structure map.

C factor

A selected constant in the API 14-E equation on fluid erosion.

Electrostatic treater

A separation device that uses alternating current charged plates to help break emulsions.

Casing jacks

A set of hydraulic lift cylinders that can be used to lift casing strings.

Choke manifold

A set of valves and/or chokes used to control drilling fluid returns on a drilling well or, in a few cases, used to control flow from a high rate well where the chokes may be in parallel or series.

Automatic J

A set or release mechanism where pickup or set down will release or set the tool.

Barite plug

A settled plug made of particles or barite or even barite and sand that are placed to seal off a zone or the wellbore.

Grind out

A shake out of solids, centrifuged or otherwise separated from the produced or circulated fluids.

Banana blade

A shape of a reamer blade that allow milling either up or down.

Diamond bit

A shaped bit body with diamonds for abrasive cutting of the formation. Also called a diamond mill.

Float collar

A short piece of casing run one to two joints above the end of casing. The collar contains a backpressure or check valve which stops cement from reentering the well after displacement into the annulus. It is useful to prevent channels in the cement until the cement is set.

Bent sub

A short section of a tool or pipe that is formed at an angle or is modified downhole by a motor to assist in entering deviated wellbores or drilling off the path of the wellbore.

Crossover sub

A short section of pipe with the proper threads cut into each end to join two pieces of pipe or equipment that do not have matching connections.

Gauge ring

A short, wireline-run tool that checks the id of a well bore.

Feldspar

A silicate mineral, often modified and sometimes part of the movable particles in a formation.

Combination log

A single assembly of various logging tools.

Bauxite

A sintered aluminum based proppant with very high strength, 3.2 g/cc density and high abrasion characteristics.

Button slip

A slip for high alloy (hard) casing.

Control line

A small diameter line, usually attached to the outside of tubing, which controls the ScSSV or other downhole tools.

Cathead

A small drum on a winch on which a hoisting cable or rope can be wrapped.

Data frac

A small fracture treatment, without proppant, pumped into a well to assess fracture breakdown pressure, fracture extension pressure, fluid loss coefficient, frac fluid efficiency and fracture closure time.

Catline

A small hoisting rope or cable.

Capillary

A small passage, usually between rock grains. These passages may have ability to absorb fluids and the pressures necessary to expel the fluids may vary inversely with capillary diameter.

Barrel pump

A small, usually hand driven pump with a long dip tube used to move chemicals from drums and barrels.

Babbitt

A soft metal alloy used in some seals and bearings.

Dummy valve

A solid body (non flowable) gas lift valve that "dummies off" a gas lift mandrel to seal the GLM or pocket.

Gas lift dummy

A solid body insert that replaces and blanks-off a gas lift mandrel pocket designed for a valve.

Acid stick

A solid stick of chloro-acetic or sulfamic acid for small scale removal of acid soluble deposits.

Cement bond log

A sonic log that determines the top of the cement column and estimates the quality of the cement bond between the casing and the formation. Works on transmission of a sound wave and identifies areas that conduct the wave and those that do not (free pipe ringing). Communication is likely if CBL>10% of unbonded mv reading. Communication is unlikely is CBL <5% of unbonded mv reading and bond length >10 ft (3 m).

Acoustic logging

A sonic travel time record of a formation using a tool with an emitter and a detector. Measures porosity and is useful to compare to other porosity longs to estimate pore filling. Also used to generate rock strength evaluations.

Bholin

A specialized viscosimeter.

Grapple

A spring like device, resembling a interlocking finger puzzle that allows a round work piece to slide through the ID when in compression, but grips the work piece (or fish) when a tension load is applied. Common in overshot fishing devices.

API monogram

A stamp indicating that the item is manufactured to API specifications.

API Fluid loss

A standard fluid leakoff test published by API.

Austenitic steel

A steel with a microstructure consisting of austenite at room temperature.

Blooie line

A straight through flow line from the wellhead to a flare pit. Often used in diverting flow during a well control incident.

Ephemeral Stream

A stream which flows only in direct response to precipitation in the immediate watershed or in response to the melting of a cover of snow and ice, and which has a channel bottom that is always above the local water table.

Caustic

A strong base chemical. Caustic soda is sodium hydroxide.

Braided wireline

A strong, braided wireline of various sizes used in retrieving tools heavier than slickline can handle. Electrical line is a braided line with a center conductor.

Alkali

A strongly basic solution.

Circulation sub

A sub in the circulating string with a side port that can be opened remotely to allow circulation from that point.

Bed

A subdivision of the classification of a sequence of rocks. A bed usually has similar lithographic features and is separated from other groupings by recognizable boundaries.

Catenary riser

A subsea riser with a large "S" that allows flexing and movement of the line.

Anode inhibitor

A substance that slows the reaction at the anode.

Colloid

A substance with particle size so fine that it exists as a stable dispersion rather than settling out.

erosion surface

A subsurface interface marking an ancient erosional event that has removed portions of one or more stratigraphic units. Typically abbreviated as ES.

Dog leg

A sudden change in the direction of the wellbore. Generally based on degrees per 100 ft.

Drilling break

A sudden increase in the ROP (rate of penetration) while drilling. May indicate a higher pressure formation, a change in lithology, a naturally fractured zone, or a poorly consolidated zone.

Flash liberation

A sudden pressure drop that causes hydrocarbon light ends to go from a liquid to a gas.

Casing hanger

A support that is screwed onto the casing and fits into the casing head.

Air lift

A surface piston driven pumping unit, similar to a beam lift unit.

Conformity

A surface separating younger from older rocks with no indication of erosion or other disturbance.

Amphoteric surfactant

A surfactant whose charge is dependent on another variable, normally pH.

Aerosol

A suspension of fine liquid droplets or solid particles in a gas.

Dome

A symmeatrical upfold of the layers of rock in which the beds dip in all directions more or less equally from a common point, any deformation characterized by a circular local uplift.

Free point

A technique for estimating the highest free point in a string of stuck pipe. It is based on a differential stretch calculation with amount of pull and the free point constant (FPC).

Frac ball

A technique for isolating multiple fracs using a short downhole settable ring or restriction and dropping a hard rubber ball between frac jobs. Two or more ring/ball sets can be used to stage frac a long zone.

Cement retainer

A temporary set plug to allow cement work above the tool. It is drilled out after the cement job.

Axial load

A tension or compression force, usually along the length of an object.

Casing head

A term that applies to the wellhead flange that forms the transition between pipe and the flange-build tree. It may be attached by threads, welding, pressure forming or lock-ring/screw devices.

Bi-metal corrosion

A type of corrosion found when dissimilar metals are joined. One part becomes the cathode and the other the anode where accelerated corrosion may be seen.

Dissolved solids

A term that expresses the quantity of dissolved material in a sample of water, either the residue on evaporation, dried at 180°C, or, for many waters that contain more than about 1,000 ppm, the sum of determined constituents, generally reported in mg/L.

Compliant expansion

A term used in expandable nomenclature signifying expansion that fits itself to non-gauge boreholes.

Diachronous

A term used to describe a surface or a seismic reflection that cuts across geologic time (dia=across, chrono=time). See chronostratigraphic and stratal surface.

Durometer

A term used to express hardness, usually of rubbers or elastomers.

Fire flood

A tertiary recovery method involving injection of air into the formation and igniting the oil. Under the right conditions, the heat produced from combustion of the heavy ends that are trapped on the sand grains lowers the oil viscosity and liberates light ends.

Flowloop

A test loop of pipe in which flow characteristics are measured.

Bioaccumulation

A test measuring the concentration or build-up of potential harmful chemicals in a living organism.

Gap test

A test of the sensitivity of the perforating charge to firing from a detonating cord. May be used to spot changes in charge explosive or differences in loading.

Borax logging

A test technique using an injected solution of borax and a detection tool to spot channels.

Biot

A theory of acoustic propagation in porous and elastic media that taken into account fluid behaviors.

Biogenic theory

A theory of petroleum formation in which the petroleum is thought to have originated from plant and animal material that has undergone transformation from deep burial.

Abiogenic theory

A theory of petroleum generation in which petroleum is thought to have formed from hydrocarbons trapped inside the earth's crust when the earth was forming.

Bomb or sample bomb

A thick walled pressure container of pressure measuring instruments or a sample container.

Flow coupling

A thicker body piece of tubing above and sometimes below a tubing profile or other tool to control erosion by fluid flow.

Crust

A thin, brittle layer of hard soil that forms on the surface of many soils when they are dry. An exposed, hard layer of materials cemented by calcium carbonate, gypsum, or other binding agents. Most desert crusts are formed by the exposure of such layers through removal of the upper soil by wind or running water and their subsequent hardening.

BW rod thread

A thread for tools and equipment that has three parallel threads per inch (similar to a AW thread). Used in applications greater than 1.75" OD.

AW Rod thread

A thread for tools and equipment that has three parallel threads per inch (similar to a BW thread). Used in applications of 1.75" OD thread or less.

Eight rounds

A thread with 8 threads per inch.

Flow T

A three-way connection. In a wellhead, a flow cross connects the master valve and the swab valve with the wing valve. Also called a tee.

Epoch

A time division of geologic time next shorter than a period.

Catwalk

A tool assembly/staging area before the Vee Door on a rig.

Free point indicator

A tool with strain gauges that is run on wireline and moved along the stuck pipe with successive pipe pulls until the stuck point is located.

Black oil

A traditional crude oil, containing alkanes (straight carbon chains) of C5 to C30+ liquids. Black oils consist of a wide variety of chemical species including large, heavy, nonvolatile molecules. The phase diagram predictably covers a wide temperature range. The critical point is well up the slope of the phase envelope.

Athie wagon

A trailer or other vehicle, designed for soft ground, often used as the staging platform for fighting well fires.

Combination trap

A trap that has both structural and stratigraphic character.

Dehydrator

A treating vessel designed to remove water from a process stream.

Check trip

A trip back to bottom after a cleanout or other operation, to check for clearance.

Dip tube

A tube from the intake of a pump that extends further into the liquid column of the well, to keep gas out of the pump.

Ethane

A two carbon chain alkane, C2H6. A gas under standard conditions of temperature and pressure.

Ethylene

A two carbon chain alkene - double bonds between the carbons and a formula of C2H4. A very common starting material for synthesis of various products.

Bayes Theorem

A two-part theorem relating conditional probability to unconditional (prior) probability, used in value of information problems but also important to acknowledge when estimating probabilities for geologically dependent prospects.

Deposit attack

Corrosion occurring under or around a deposit on a surface.

Corkscrew

Compressional deformation of tubulars to the point where the tubing resembles a corkscrew. The condition may be temporary if the metal is not yielded past the elastic recovery point. Tubulars that are corkscrewed may be pumped through but will stick most diameters of tool strings.

Autocorrelations

Computation of a spatial covariance model for regionalized variable, measuring a change in variance (variogram) or correlation (correlogram) with distance and/or azimuth.

EC

Conductivity measured directly in reciprocal units of resistance and reported in mmhos/cm. EC is an indirect measure of total dissolved solids (TDS).

Conformance

Conformance is a measure of the uniformity of the flood front of the injected drive fluid during an oil recovery flooding operation and the uniformity vertically and areally of the flood front as it is being propagated through an oil reservoir.

Class A

Construction grade Portland cement.

Balancing agreement

Contractual agreement between legal parties to account for differences between chart measured quantities and the total confirmed quantities at a measuring point such as a plant. They are used to track over/under production relative to entitlements between producers, over/under deliveries relative to measured volumes between operators of wells, pipelines and LDCs.

Cap a well

Control a blow out or seal at the surface after a P&A.

Discretization

Converting a continuous distribution to a discrete distribution by subdividing the X -range. The discrete variable has values equal to the means of the subranges and probabilities equal to the chance that the variable would fall into that subrange.

Erosion-corrosion

Corrosion acceleration by passage of a high velocity flow or impingement of solids. May remove the thin, protective oxide film that protects exposed metal surface.

Galvanic

Corrosion between two dissimilar metals - couplings, centralizers, pumps, packers, profiles - usually severe metal loss on one metal near contact point. May see galvanic loss on a single metal with current.

Filiform corrosion

Corrosion occurring under a coating in a pattern of filaments. May resemble threads.

Ecorr

Corrosion potential.

Contingency

Cost engineers offer the following definition: cost contingency is the amount of additional money, above and beyond the base cost, that is required to ensure the project's success. More generally, contingency is an additional amount set aside for routine cost overruns or for things that were not accounted for. Some companies specify the difference between a budgeted amount and a high percentile such as P85 or P90 as a contingency.

Abandonment cost

Costs associated with the abandonment of facilities or services, including costs for the removal of facilities and restoration of the land.

Chloride Stress Cracking

Cracking of a metal under combined action of tensile stress and corrosion in the presence of chlorides and an electrolyte (NACE). Starts at a pit, scratch or notch. Crack proceeds primarily along grain boundaries. The cracking process is accelerated by chloride ions and lower pH.

Acid fracturing

Creating a fracture in a carbonate and etching the face of the fracture to preserve flow capacity down the fracture.

Dead oil

Crude oil without gas. May have been degassed mechanically or by gas breakout during storage.

Disordant

Cutting across surrounding strata.

Cut and strip

Cutting the logging cable and threading it through the drill pipe when fishing for logging tools.

Damping

Damping is the dissipation of energy with time or distance.

Crosswell seismic profiling

Data that is acquired with a downhole seismic source in one well and downhole seismic sensors in a second well. CSP data provide high-resolution 2D images of geologic conditions across interwell spaces. Typically abbreviated as CSP.

Eccentricity

Decentralization of pipe in the hole. 100% eccentric is against the hole wall.

Creaming of emulsions

Density separation state of emulsions, often where color variances are noted.

Eolian

Depositional environment formed by wind.

Abyssal

Depositional environment of the deepest areas of the oceans.

Fluid contact

Depth of the contact point in a specific well between immiscible phases.

Fretting corrosion

Deterioration at interfaces of two metals accelerated by their relative motion.

Allogenic

Detrital rock constituents and minerals derived elsewhere from older formations and redeposited.

Exploitation

Development of a producing reservoir.

Graviometer

Device that records the specific gravity of a fluid.

Desander

Devices that typically use centrifugal flow paths to spin solids out of a drilling or circulating fluid. Also known as desilter.

Deaerator

Devices used to separate gasses from liquids.

Dissimilar metals

Different metals that may form an anode-cathode pair in corrosion cell conditions.

G-function

Dimensionless function used in shut-in time normalized to pumping time. It is used to analyze pressure-dependant leakoff.

Deflocculation

Dispersing a clump or a gathering or "flocculated" of particles. Usually accomplished by dispersants or solvent thinners.

Drillable

Downhole tools and equipment that can be broken up by the bit.

Final circulating pressure

Drill pipe pressure required to circulate at the selected kill rate.

Directional drilling

Drilling the wellbore in a planned trajectory.

Drill out

Drilling through the cement after a primary cement job as the hole is deepened.

Air drilling

Drilling with air instead of drilling mud (requires diverters at the surface to handle cuttings and formation fluids).

Clay flocculation

Dropping suspended particles out of a fluid by agglomerating them into larger, easier separated particles.

Anhydrous

Dry, without water.

Echo meter

Echo Meter™ is the trademarked name for a commercial tool that measures the height of a fluid (or solid) level by means of a reflected sound wave.

EconoProp

EconoProp™ is a trademarked name for an inexpensive light weight ceramic (man made) proppant.

Density-depth function

In a seismic context, the density-depth function shows that the change in density with increasing depth is often a result of compaction. Age, lithology and porosity modification are also factors.

Adsorption band

In a seismic context, this is the range of wavelength energy that can be adsorbed by a given formation.

Absorptance

In a seismic context, this is the ratio of the energy absorbed by a formation in relationship to the total energy passing through it.

AHV

In a subsea context, AHV abbreviates anchor handling vessel.

BML

In a subsea context, BML stands for below mud line.

CATs

In a subsea context, CAT stands for connection actuation tool.

AUV

In a subsea context, an AUV is an autonomous underwater vehicle.

ADP

In a training context, ADP stands for accelerated development program.

Active corrosion

In context of corrosion, a corrosion state where a metal is corroding without control by a reaction product (or corrosion product layer).

Admissability

In context of semivariogram models, this is the condition in which the kriging variance is ≥0 for a given covariance model. Also known as positive definite. A semivariogram model is said to be admissible if it does not generate negative variances under any conditions.

Bar

In geologic terms, a bar is a mass of sand or other materials deposited in the bed of a stream channel.

Crater

In the context of a blow out, a crater is a depression formed from a release of gas through loose soil at the surface or sea floor.

Double grip

In the context of a packer, a double grip is slips that prevent either upward or downward movement.

Gang

In the context of a rig, a gang is the crew.

Gang pusher/ tool pusher

In the context of a rig, a gang pusher is a supervisor.

Geronimo line

In the context of a rig, a geronimo line is a safety slide or a line from the derrickman's platform to the ground, used in an emergency.

Aerobic

In the context of bacteria, this term describes bacteria that require oxygen to survive and multiply.

Eutectic

In the context of brine, eutectic is a mixture of substances having a minimum solidification/melting point.

Dropper

In the context of cementing, a dropper is the housing with valves and bails that controls the position and dropping of the plugs used in cementing.

Contaminant

In the context of cementing, contaminant is placing a material in a cement slurry (usually already in a wellbore) that purposely prevents the cement form setting so that it can be circulated out of the wellbore.

Binder

In the context of coatings, a binder is the nonvolatile portion of a coating.

Gooseneck

In the context of coiled tubing, a gooseneck is the CT guide arch over the injection head.

Friction lock

In the context of coiled tubing, friction lock is a state where the wall drag or friction is high enough to prevent further movement of the pipe.

Bending cycle

In the context of coiled tubing, this term refers to the process of cycling coiled tubing from a yielded position, through a transition region, and back again. Running coiled tubing from the reel into a well and back to the reel involves six bends or three cycles.

Cement

In the context of completions, cement is typically the Portland, silicate, and/or pozzilin, etc., mixtures used to form a stone-like permanent seal between the pipe and the formation.

Fee land

In the context of contracts, fee land is land where mineral and surface rights are controlled. Usually private lands, rather than public or government.

Back-in contract

In the context of contracts, this contract is a type of interest in a well or least that becomes active at a specified time or a specified event.

Chevron pattern

In the context of corrosion, a cheveron pattern is a V-shaped pattern on a fatigue or brittle-fracture surface. The pattern may also be one of straight radial lines on round specimens.

Electromotive force series

In the context of corrosion, an electromotive force series is a list of elements arranged according to their standard electrode potentials.

Arrest mark

In the context of crack development, this term describes characteristic markings (ridges, tears, risers, etc.) on fracture surfaces after fatigue crack of fracture propagation (also known as beach marks, clamshell marks, and conchoidal marks).

Baume

In the context of density, the baume scale is a density scale used in mineral acid strength measurement.

AHD

In the context of depth, AHD stands for along hole depth or measured depth.

Concession

In the context of leases, a concession is a grant of access for a defined area and time period that transfers certain rights to hydrocarbons that may be discovered from the host country to an enterprise. The enterprise is generally responsible for exploration, development, production and sale of hydrocarbons that may be discovered. Typically granted under a legislated fiscal system where the host country collects taxes, fees and sometimes royalty on profits earned.

Dead line

In the context of lift systems, a dead line is that part of a wireline or cable that is attached to a fixed anchor point and does not move through a pulley or other mechanical device.

Azimuth

In the context of logging, this is a horizontal plane; it is the angle (measured clockwise) of well path departure usually from magnetic north. It may also be expressed as the compass direction of the path of the well bore as measured by a borehole survey. (Note: check the specifics of the survey for the details).

Bar-vent

In the context of perforating, a bar-vent is a vent in the tubing or treating string open by a drop bar used to fire a perforating gun.

Big hole charge

In the context of perforating, a big hole charge is a perforating charge with the liner shaped to create a large entrance hole but a shallow penetration. See Deep Penetrating Charge.

Drop bar

In the context of perforating, a drop bar is a bar dropped from surface to set off a TCP gun in a near vertical well.

Ablation debris

In the context of perforating, these are small pieces of rock broken up by the perforating process.

Anvil

In the context of perforating, this is the strike plate over a TCP, drop-bar firing system.

Freeze point

In the context of pipe movement, freeze point is the depth at which the pipe is stuck.

Caisson

In the context of pipes, a caisson is a large outer pipe, often a form or a barrier.

Double

In the context of pipes, doubles are two joints screwed together.

By-pass

In the context of piping, this is a secondary flow path that goes around a repair point or other feature.

Booster pump

In the context of piplines, this is a pump located along the length of a pipeline to raise the pressure and overcome friction or elevation losses.

Adiabatic

In the context of processes, this is a process without exchange of heat with the surroundings.

Absorption

In the context of processing, this is the ability of one material to absorb another.

Dynamic event

In the context of propellant fracturing, a dynamic event is an event such pressure surge or fracturing that occur over a few hundred milliseconds.

Cracking

In the context of refining, cracking is breaking longer chain hydrocarbon molecules to shorter chain molecules.

Developed reserves

In the context of reservoirs, developed reserves are expected to be recovered from existing wells including reserves behind pipe. Improved recovery reserves are considered developed only after the necessary equipment has been installed, or when the costs to do so are relatively minor. Developed reserves may be sub-categorized as producing or non-producing (SPE).

Block

In the context of rigging, a block is a pulley (sheave) or set of pulleys, mounted in a housing. The blocks on a rig are the crown (stationary) block at the top of the derrick and the traveling block.

Decision tree

In the context of risk, a decision tree is a sequence of nodes which are either a decision or an uncertainty, and outcomes associated with each mode. The purpose of a decision tree is to define the set of scenarios and the sequence of events that guide the evaluation of risk and return. It is displayed as a pictorial device, consisting of nodes and branches, that describes two or more courses of action and the resulting uncertainties with probabilities of occurrence, as well as possible subsequent actions and uncertainties. The solution to the tree consists of a preferred course of action or path along the tree, together with the resulting expected value.

Expected value

In the context of risk, an expected value is the weighted average using probabilities as weights. For decisions involving uncertainty, the concept of expected value provides a rational means for selecting the best course of action and for forecasting portfolio level performance.

Deterministic estimate

In the context of risk, deterministic estimate is an estimate using a single number value. It does not account for ranges in value or probability of occurrence for the parameter.

Abject failure

In the context of risk, this is a failure mode that can cause the cancellation of or immediate halt to a project or event. Generally expressed as a percent probability.

Blinding

In the context of screening, blinding is obstructing an aperture or opening by particles or debris.

Back up ring

In the context of seals, this device is a ridged ring-like support next to a seal to provide higher pressure or temperature support.

Biogenic sources

In the context of sedimentary rocks, biogenic sources are rocks such as coal resulting from decomposition of animal or plant deposition.

Breaking down

In the context of the drill string, breaking down is to separate the stands into single joints.

Ball

In the context of tool operation, a ball is a steel, aluminum, brass or plastic ball pumped or dropped downhole to shift or operate a tool.

Cushion

In the context of underbalance, a cushion is a fluid column margin of some type. Usually well control mud weight, gas column, etc.

Gradiomanometer

In the context of well logging, a gradiomanometer is a device that measures the density of fluids along a fluid column.

Annular injection

Injection of fluids down the annulus or Common as a gas supply path for gas lift. Also used in some fracturing operations, to spot fluids downhole when no packer is used or a type of injection valve is in the tubing to allow entry of chemicals, gas or water.

Flooding

Injection of gas or water into a reservoir to drive oil towards a producing well or set of wells.

Crevice corrosion

Intensive localized electrochemical corrosion occurs within crevices when in contact with a corrosive fluid. Will accelerate after start.

Effective porosity

Interconnected, drainable porosity.

Gas permeation

Invasion of gas into a solid, usually an elastomer, but sometimes referring to a metal.

Brownian motion

Irregular motion of colloidal sized particles when suspended in a fluid. The effect in simplest terms is caused by thermal driven motions.

Ground roll

Is a robust, high-amplitude wave produced by onshore seismic sources that travels along the Earth/air interface. A ground-roll wave does not propogate in the interior (body) of the Earth. See Rayleigh wave.

Alluvial fan

Land counterpart of a river delta. Characteristic of sediments that have been transported by a fast moving stream then dropped out of the flow as the stream velocity drops as it spreads out. Typical of zones of heavy water runoff such as found at the base of mountains in arid and semi arid climates where flash floods may be seen. Often poorly sorted with pebble to boulder sized sediments. Weak cementing typical.

Acreage

Land leased for drilling exploration.

Alkaline flooding

Large scale injection of pH>7 fluids. The basic materials may react with oils to form reactants that can reduce viscosity or affect wetting.

Abyssal plain

Large, flat ocean floor, usually near a continent and usually over 4km (13100 ft) ss.

Gravel

Large, well sorted and consistently sized sand used to hold back a soft formation.

Agglomerates

Larger particles of material made up of small, independent pieces.

Galena

Lead sulfide, PbS. A mud weighting additive for high mud weights.

Amides

Linear or ring compounds with a CO-NH2 attachment. Common in surfactants.

Bacterial remediation

Liquefaction or break down of oily waste or clean-up of oil spills by the use of the naturally occurring oil consuming bacteria, chiefly ultramonis and pseudomonis.

Gas cut

Liquids with free gas. Usually refers to drilling or completion liquids. May indicate a kick if the gas is present in large enough quantities.

Exfoliation corrosion

Localized and subsurface corrosion in zones often parallel to the surface that result in leaving thin layers of uncorroded metal resembling the pages of a book.

Body rig

Locks slips, mandrels or cones in place in a downhole tool.

Cavings

Loose formation materials that falls into the wellbore.

Extraction loss

Loss of volume due to removal of gasses or liquids during processing.

Circulation losses

Losses for any reason while circulating the well.

Fisheyes

Lumps of undispersed polymer in suspension in the pill.

Block Kriging

Making a kriging estimate over an area. For example, to estimate the average value at a grid cell, the grid cell is discretized into subcells, a kriging estimate is made for each subcell, and then these are averaged together to produce a single value. This final value is placed at the original grid node.

Barge

Marine vessel without its own propulsion.

Flag

Marking the pipe or wireline with a paint stripe.

Filtrate reducers

Materials that reduce the fluid loss from a wellbore fluid. May include Bentonite clays, lignite, CMC, etc.

Flocculants

Materials used to increase visicosity. They cause colloidal particles to group into bunches or flocs.

Continuity

Measurement of a formation being present over a large area.

Capacitance tool

Measures the fluids capacitance -- uses the wellbore fluid as the fluid between plates of a capacitor.

Ball operated

Mechanical device activated by pumping a ball of a certain size down the tubing in the injected or circulated fluid.

Amphoteric metal

Metal that may corrode in either acids or alkalines.

Batch mixing

Mixing a specific volume of a treating fluid in a properly sized tank Ð as opposed to mixing-on-the-fly.

Cominggle

Mixing production. In a well, when two or more zones are mixed to assist in economic production. In a flow line, when multiple crude source streams are mixed.

Front end costs

Money paid or costs at the start of a project (engineering, legal, contracts, etc.), before on-site activities begin.

Casing reciprocation

Movement of casing up and down to help remove mud and replace it with cement slurry.

Clay migration

Movement of clay particles, usually after partial disintegration of the clay matrix due to absorption of water or reaction to other effects such as ions, velocity, crushing due to overburden, etc.

Fingering

Movement of one fluid through another, most commonly used in EOR application.

Fines migration

Movement of small particles (usually <5 microns) through the rock pores.

Barrier

NORSOK: an envelope preventing hydrocarbons from flowing unintentionally from the formation, into another formation or, to surface

Casing head gas

Natural gas condensate, usually C2 to C8+. The C5-C8 components condense to a very volatile liquid when the temperature decreases near the wellhead.

Coal Bed Methane

Natural gas formed during the coalification process and trapped within and adsorbed to the coal.

Conventional gas

Natural gas in a normal media, capable of flowing without other influences.

Artificial Lift

One of several methods that provide pressure assistance to increase flow from a well. The most common systems lighten (decrease density) of the flowing fluid (gas lift), or remove all or part of the liquid head from the reservoir (beam and electric submersible pumps).

Chrome

One of several steel compositions for tubing that uses chromium for increased resistance to CO2.

Casing

One of several strings of steel pipe in a well design that, together with cement, forms a barrier to fluid movement along the drilled hole. It is commonly at least partly cemented in the wellbore.

Explosive fracturing

One of several techniques used to break the rock in the near well area. It was an early stimulation method. Fractures formed in this method are short. Although still used, its best application is in perf breakdown and overcoming some near well damage.

Gas lift

One of the artificial lift methods that uses gas injected down the annulus and interspersed into the flowing fluids in the tubing to lessen the density and to assist in vertical flow by gas expansion.

Depreciation, declining balance

One of the liberalized methods of computing depreciation (normally used for tax purposes). Under this method, the depreciation rate is stated as a fixed percentage per year and the annual charge is derived by applying the rate to the net plant balance, which is determined by subtracting the accumulated depreciation reserve (From AGA).

Barite

One of the many forms of the barium sulfate mineral. The BaSO4 material is used in drilling mud as a weighting agent and can produce a slurry of over 20 lb/gal in water.

Anderson-Darling method

One of three common goodness-of-fit metrics used when fitting probability distributions to data (the others being the chi-square and Kolmogorov-Smirinov), which places additional emphasis on the fit at the extreme values of the distribution.

Chi-square

One of three metrics used to judge the goodness of fit between data and a density function, specifically, Σ(1/yi)(yi - fi)2 , where fi is the class frequency from the histogram, and yi is the value of the density function taken at the class midpoint. Chi-square is also a classical random variable, like a normal or log-normal variable.

Financial option

One of two basic types (puts and calls) of financial instruments entitling the owner to sell (put) or buy (call) one share of a commodity for a specified price on or before a specified date.

Enhanced oil recovery

One or more of a variety of processes that seek to improve recovery of hydrocarbon from a reservoir after the primary production phase.

Field

One or more reservoirs grouped by or related to the same general geologic structural feature or stratigraphic condition. There may be two or more reservoirs in a field which are separated vertically by intervening impervious strata, or laterally by local geologic barriers, or by both."

Confirmation well

Or appraisal well, conformation well, delineation well, a secondary well, after a field discovery well, drilled to help determine field extent, volume or potential rate.

Fluid pound

Or rod pound - a beam lift term where the pump is filled with gas from pump-off or too fast of an operating speed (rod speed).

Flushed zone

Part of the rock that has been flushed with a sweep fluid. The area may have little hydrocarbons remaining.

Abrasive

Particles propelled at a velocity sufficient to cause cleaning or wearing away of a surface.

Clinker

Pea to marble sized pellets of raw cement prior to grinding.

Absolute permeability

Permeability to a single phase fluid in a cleaned core.

Conventional crude oil

Petroleum in liquid form capable of flowing naturally.

Casing tongs

Pipe tongs used to make connections.

Baffles

Plates in a separator on which the flow impinges and breaks out gas.

Anodic protection

Polarization to a higher oxidizing potential to achieve a reduced corrosion rate (promotes passivity).

Conglomerate

Poorly sorted collection of sediments, generally formed in a very high energy environment. Similar to sandstones but have much larger grains (pebbles grade 4 to 64 mm). The space between the grains may be partly or completely filled with sand grains.

Centrifugal pump

Pump with an impeller or rotor that spins in a housing and the drag forces on the fluids cause them to flow.

Fraangible valve

Purposely breakable valve, usually a flapper in a fluid loss device.

Bitumen

Pyrogeneous, essentially non reactive, hydrocarbon. Most of these are not considered as movable through the reservoir under normal conditions of flow.

Formation gas oil ratio (FGOR)

Quantity of gas measured at standard conditions dissolved in one stock tank barrel of oil at current reservoir pressure and temperature.

Extrusion gap

Radial gap between the maximum rated casing ID and the minimum OD immediately adjacent to the packing element.

Alpha decay

Radioactive decay process where the loss of an alpha particle from the nucleus lowers the atomic number by two and the atomic mass by four.

Geiger-Muller counter

Radioactive measuring device.

Bend radius

Radius of curvature of flexible pipe, measured to the pipe centerline.

Gas gravity

Ratio of the gas density to the density of air. Equal to the ratio of molecular weight of gas to that of air (28.97).

Bottom out

Reach final drilling depth.

Bump the plug

Reaching bottom with the plug during a cementing operation or fluid displacement operation.

Depletion

Reducing the fluid content of a formation by production of that fluid.

Casing wear

Reduction in thickness x 100 / original thickness. Most common wear is from rotating strings during drilling.

Cation exchange capacity

Related to concentration of cations on negatively charged clay surfaces that, when brine is present, can be exchanged/satisfied for/by cations in the brine. The total of exchangeable cations that a porous medium can absorb, expressed in moles of ion charge per kilogram of clay or mineral.

Depositional energy

Relating to the energy of the transport mechanism that carries particles into an area of deposition. Low energy environments may contain large quantities of fines where high energy environments are usually marked by larger and more consistent grain sizes.

Contracted reserves

Reserves of hydrocarbon dedicated to fill a specific contract.

Flood plain

Reservoirs that occur along ancient rivers where the rivers overflowed. Deposits are mostly silt and mud.

Apparent resistivity

Resistivity recording where the measured value differs from the true or defined state by the influence of the mud column, invasion of a zone by fluids, or wellbore anomalies.

Back flow

Return flow from injection of a fluid into a formation.

Back scuddling/ back wash

Reverse circulating.

Black flushing

Reverse flow of a fluid, usually in a well treatment or injection well, where flow from the reservoir to the wellbore, often at high drawdown, is used to clean fluids and shallow particulate damage from the near-wellbore area.

Bioturbation

Reworking of the sediment by burrowing animals.

Asphalt

Ring compound materials in the oil composed of carbon, hydrogen, sulfur, nickel and other trace materials. Asphaltenes are mostly very small platelets (35 A) suspended by micelles of maltenes and resins and carried through the oil. They precipitate by agglomeration as the micelles break apart on shear, mixing with acids, or other interruption of the micelle stability. Also called asphaltene.

Cavings rock

Rock fragments that spall or break off the wellbore walls. Usually found as fill in the hole.

Argillaceous

Rocks or substances composed of clay minerals, less than 0.625mm, or having a high proportion of clay in their composition such as shale and slate.

Casing rotation

Rotating the casing string during primary cementing to remove mud and improve primary cement bonding and isolation.

Float show

Same function as a float collar but run on the end of the casing.

Anoxic

Same with anaerobic

Arenaceous

Sand particles, 0.625 to 2 mm on the Udden-Wentworth scale.

CO2 injection

Secondary recovery technique for oil. The carbon dioxide gas is injected and alternated with water. CO2 lowers the viscosity of most oils, but may trigger severe asphaltene and scale precipitates.

Button up

Secure the well or close in.

Compartments

Segregated flow units of a main reservoir that have a poor flow connection or no flow connection to the main reservoir.

Doodlebug

Seismograph.

B profile

Seldom used name for a SSSV profile.

Dealloying

Selective corrosion of one metal in an alloy.

Ball sealers/ ball diverters

Small, rubber-covered, hard centered balls that can seal individual perforations during a chemical treatment.

Drag blocks

Spring loaded blocks on a packer or other tool that contact the pipe wall, producing resistance to movement. They aid in setting of packers.

Air density

Standard density of dry air, free of CO2 at 0 degrees C is 1.292 g/L. At standard temperature and pressure, air density is 0.763 lb/ft3.

Break circulation

Start circulating fluid from a static condition.

Alkenes

Straight or branched chain chemicals with some double bonds between carbons.

Alkanes

Straight or branched chain hydrocarbons with single bonded carbon atoms. Describes most oils.

Groundwater

Subsurface water that fills available openings in rock or soil materials to the extent that they are considered water saturated.

Back surge

Sudden backflow of a well, usually to clean the perforations.

Downhole gauges

Surface reading, downhole located gauges capable of measuring pressure, temperature and/or flow rate.

Bedding plane

Surface separating layers in a sandstone. Usually bedding planes mark the transition of the particle transport event. An accumulation of minerals or other materials laid down at the time of rock deposition or generated by reworking, that may create significant vertical permeability barriers in a sedimentary rock.

Erodible

Susceptible to erosion.

Absolute temperature

Temperature measurement starting at absolute zero (total absence of heat).

Closed chamber testing

Testing the well into a chamber open at the bottom, but closed at the surface.

Effective shot density

That number of the perforations that are open and flowing.

Control gas

That part of the gas stream used to actuate or operate equipment (may be rendered unusable for sale due to pressure drop, etc.).

Damaged (crush) zone

The area of the rock adjacent to the perforation tunnel where permeability may be 50% less than initial, undamaged permeability.

Confidence Interval (CI)

The 90% confidence interval for a variable X is the range of values between P5 and P95. Similarly the 80% confidence interval is the range from P10 to P90. Confidence intervals are used as subranges of practical interest, representing where the value of X will fall the vast majority of the time. Abbreviated CI.

Coil tubing unit

The CT, reel, injector head, power pack, control unit and pressure control equipment used in a coiled tubing job.

Equivalent Circulation Density (ECD)

The ECD is an important parameter in avoiding kicks and drilling fluid losses, particularly in wells that have a narrow range (or window) between the fracture gradient and the pore pressure gradient.

Gauge diameter

The OD of a bit or tool used downhole.

Dilatancy

The ability of a rock to expand through micro-fractures in consolidated rocks or grain position shifts in unconsolidated rocks.

Facility operability

The ability of an organization to operate a facility in a safe and efficient manner.

Clay swelling

The absorption and modification of the clay matrix by a reactive water.

Filter cake lift-off

The act of lifting off part of the mud filter cake, at the most permeable sections of the rock, in response to flow produced by draw down.

Accretion

The action of particles forming adhering clumps on pipe.

Drilling

The action of placing a hole to a depth and location.

Burst rating

The actual minimum burst pressure derated by a safety factor. The derated burst is used as a maximum when pumping.

Excess cement

The amount of cement over that required to cement the zone. Usually between 30% and 100% depending on hole diameter unknowns and contamination risk.

Gravel reserve

The amount of gravel above the top perf, after the job, in a well with deviation less than about 50o.

Available overpull

The amount of unused pull capacity of a rig after picking up the entire string weight.

Buoyancy

The amount of weight that is offset by lift from the fluid when the piece of equipment is immersed in the fluid.

Formation evaluation

The analysis of formation character or properties, usually by remote logs.

Contact angle

The angle of intersection of two fluids on a given surface. Describes wetting and non-wetting behaviors.

Build angle

The angle of the inclination in the kickoff section when describing a deviated well.

Dip

The angle that the structural surface or bedding plane or fault surface makes with the horizontal. Measured perpendicular to the strike and in the vertical plane.

Back slide

The annulus above the packer.

Annulus

The area between the O.D. of an inside string and the I.D. of an outside string.

Depositional environment

The conditions of sediment transport and deposition at the time the formations were laid down.

Cementing head

The connection between the wellhead the lines from the cement trucks. A rotating head (uncommon except on top-drive rigs) allows the pipe to be rotated during the cement placement to assist in displacing mud and preventing channels.

Cable head

The connection of the braided cable to the rope socket or attachment to the tool string in a wireline conveyed BHA.

Collar

The connection or coupling on jointed pipe. It the strict sense, it is the section with female x female connections.

Coupling

The connection point of jointed pipe. It may be a steel shell with female threads to which the pins are connected or a formed female connection (box) on the end of tubing.

Gripper block

The contacting blocks on a coiled tubing injector that grip and move the coiled tubing.

Christmas Tree

The control sections that sits above the basic wellhead. It may contain hangers, master valves, annular valves, wing valves, and gauges or pressure, flow rate or monitoring measurement equipment.

Cavitation

The creating of a high speed, very low pressure vapor bubble that quickly and violently collapses. Very detrimental to surfaces in the near proximity. Often seen in severe turbulent flow.

Buckling

The deformation of pipe in compression as it moves from straight to sinusoidal to helical shapes in the hole. Usually in the elastic range.

Bulk density

The density of a rock as it naturally occurs (as compared to specific density of the grains). Includes the pore structure.

Grain density

The density of the rock components, without the effect of porosity.

Casing point/ casing shoe depth

The depth at which a casing string is set, either by design or because the mud can no longer control the pressure of the next deeper zone without adding weighting agents that would break down upper intervals.

Fluid contact

The depth of the interface between the oil and water, oil and gas, or water and gas.

Corrosion

The deteriorating chemical reaction of a metal with the fluids with which it is in contact.

Angle of repose

The deviation angle (from vertical) at which a solid material will no longer fall down the pipe, but will begin to accumulate on the pipe wall. The value of this for dry, round sand is about 62¼ and for wet sand about 50¼ to 60¼ depending on size, shape and moisture.

Boycott settling range

The deviation between 30o and 60o where refluxing (dropout and reverse flow) of particles and heavier liquid occurs in a lower rate well. The area in which gas bubbles may rise through fluid at 4 to 7 times that in a vertical well.

Blender

The device that takes in fluid feed, mixes in sand and then outputs to the pump truck.

Drawdown

The difference between two pressures. Completion drawdown is the pressure differential from the formation near the wellbore to the wellbore.

Differential pressure

The difference in pressure between upstream and downstream of a measurement point.

Down dip

The direction going down the tilt angle of the formation.

Crossline

The direction that is perpendicular to seismic receiver lines.

Departure

The distance from the kelly bushing horizontally to the end of the well.

Fluid invasion (invaded zone)

The distance outward from the wellbore to the leading edge of the lost fluids. Varies with the permeability of the zone.

Flush production

The early, higher rate production that comes from the larger pores, fractures and vugs that empty quickly. Delivers a small, high rate flow every time the well is shut-in (recharges) and is brought back on line

Fracture closure pressure

The earth stresses acting to try to close a hydraulic fracture offset by the pore pressure.

Equivalent Circulating Density

The effective fluid density that the formation sees when the friction pressure on the fluids returning to surface is added to the fluid density.

Base Management

The efficient delivery of proved developed reserves through excellence in Reservoir, Well and System management.

Derrick

The elevated section of a rig that rises above the substructure and houses the crown block and draw works.

Bernoulli equation

The equation is used in the design of chokes and explains the manner in which pressure in the body in the body of the choke, downstream of the first pressure drop, is lower than the eventual recovery pressure at the end of the choke.

Drilling rig

The equipment at the surface used to lift and run the drilling string, provide the rotation and pump fluids down the string.

Bottomhole assembly

The equipment or tools at the bottom of the tubing or drill string. The BHA is changed to achieve a certain result.

Equivalent mud weight

The equivalent mud weight felt by the formation when circulating with a certain mud weight and holding a backpressure. A 10 lb/gal mud in a 10,000 ft well with 1000 psi backpressure would generate an equivalent mud weight of about 11.9 lb/gal.

Continuous phase

The external phase in an emulsion.

Box

The female part of the connection.

Cloud point

The first appearance of microsized paraffin crystals in suspension in the oil.

Bed rock

The first solid rock under loose sediments.

Free water knock out

The first stage of separation in a crude that contains a large amount of water.

Conductor casing

The first string of casing run, usually to keep rocks or dirt out of the wellbore. It is usually not cemented in place. It may be jetted in, driven in, drilled in or installed in an excavated hole.

Area open to flow

The flow area generated by perforations across a zone of interest. Typical calculated perforation entrance hole areas are 1% to 6% of the pipe body. Used in pressure drop calculations.

Flowline

The flow connection from the wellhead to the separation facility, pipeline or storage unit.

Diluent

The fluid added to a concentrated mixture to reduce the concentration of an internal phase or reduce its viscosity.

Carrier fluid

The fluid that carries proppant or other material into the well.

Frac fluid

The fluid used in a fracturing treatment, may include pre and post treatment fluids.

Drill in fluid

The fluid used to drill the pay zone.

Drilling mud

The fluid, water, oil or gas based, that is used to establish well control, transport cuttings to the surface, provides fluid loss control, lubricates the string and cools the bottom hole assembly.

Effluent

The fluids and solids, perhaps in a mixed stream, produced from a well.

Gas saturation

The fraction of the porosity in a zone that is occupied by free gas.

Fluid saturation

The fractional or percent amount of pore space which a specific fluid occupies.

Base Gas

The gas required in a storage reservoir to cycle the working gas volume.

Filtration level

The generally statement of the largest size particles in a fluid after passing through a filter.

Fracture gradient

The gradient needed to initiate a fracture.

Geothermal gradient

The gradient reflecting the amount of temperature rise as the well depth increases. Normally about 1.1 to 1.8o F per 100 ft of true vertical depth increase.

Fracture network

The groupings of fractures, possibly interconnected, that form a enhanced flow unit.

Conductance

The reciprocal of resistance in direct current logging measurements. Measured in siemens (formerly mhos).

Geothermal energy

The heat of the earth, usually from produced natural steam, heat recovered from circulated water or direct heat-to-energy conversion (on-going research).

Coiled tubing injector head

The hydraulic powered chain driven unit that snubs or strips coiled tubing into or out of a well.

Contingent resources

The hydrocarbons that are estimated to be potentially recoverable from known accumulations, but which are not currently considered to be commercially recoverable.

Fracture pad/ pad fluid

The initial part of the fracture fluid that creates the fracture width and controls the initial fluid loss but contains no proppant.

Alpha wave

The initial wave of gravel transport when packing a well with a deviation over 55o.

Discovery well

The initial well in the field that tests hydrocarbons. (NOTE: there is a difference between a discovery and an exploratory well. The first well which reaches the oil is the "discovery".

Bed wrap

The innermost wrap of coil or cable on a spool or reel.

Cummulative distribution

The integral of a density function. The functional relationship between cumulative probability (on the vertical axis) and value.

Burst

The internal fluid pressure that will cause the onset of pipe yield.

Dispersed phase

The internal phase in an emulsion - i.e., the droplets or bubbles.

Filter cake lift-off pressure

The inward differential pressure difference that will result in part of the filter cake being removed from the face of the formation (usually over the most permeable and higher pressured sections).

Estimation variance

The kriging variance at each grid node. This is a measure of global reliability, not a local estimation of error.

Filter cake

The layer of solids stranded on the face of permeable formations by liquids driven into the rock by pressure differential towards the formation. When sized correctly the filter cake may completely stop losses.

Fracture half length

The length of one wind of a fracture from the wellbore to the tip.

Filtrate

The liquid that leaks off into the formation during fluid loss.

Gas condensate

The liquids, generally straight chain alkanes in the C2 to C6+ range, than can condense from gas when the temperature and pressure drop sufficiently low.

Fracture proppant pack density

The loading of proppant per square foot after the fracture has been placed. Commonly between 4 and 16 lb/ft2 of fracture face.

Explosive limits

The low and high range (wt %) of a combustible gas mixed in air that can be ignited at ambient pressure and temperature.

Detectable limit

The lower limit of analysis for a test of a piece of equipment for a specified measurement.

Aniline point

The lowest temperature at which equal volumes of freshly distilled aniline and an oil are completely miscible. Aniline points are especially important when considering the possibility of running downhole tools with rubber parts exposed to oil based muds. If expected circulating bottom-hole temperature is greater than aniline point of exposed rubber part, then it is not advisable to run tools with such exposed rubber parts in that drilling scenario.

Density

The mass per volume of a substance. Density of fresh water is 8.33 pounds per gallon or 1 gram/cc.

Cementation

The material in the rock between the grains that binds the grains together.

Filter media

The material used to make up a filter bed. Common filter media are DE, sand, various fibers, etc.

Completion technical limits

The maximum production or flow capacity possible by the best completion attainable.

Gas formation volume factor

The volume of reservoir gas resulting in one standard cubic foot.

Closure pressure

The pressure at which a fracture closes. Related to the closure forces in a formation.

Bubble point

The pressure at which gas begins to break out of an under saturated oil and form a free gas phase in the matrix or a gas cap.

Circulating pressure

The pressure generated by the mud pumps and, in normal circulation, exerted on the drill string.

Capillary pressure curve

The pressure necessary to achieve a given non-wetting fluid saturation of a rock.

Fracture extension/ propagation pressure

The pressure necessary to extend the fracture once initiated. The fracture extension pressure may rise slightly with increasing fracture length and/or height because of friction pressure drop down the length of the fracture.

Fracture breakdown (initiation) pressure

The pressure needed to initiate a fracture.

Eon

The primary division of geologic time -- from oldest to youngest - the Haldean, Archean, Proterozoic, and Phanerozoic.

Depletion plan

The primary process for Life of Field resource management. The Depletion plan sets out the framework of how Resource Management underpins efficient exploration of the resource.

Float valve

The primary, bottom hole valve in the float collar or shoe that allow the casing to self fill while running and allows the cement to pass into the annulus but helps prevent cementing U-tubing after the job. Drillable and subject to erosion wear.

Gas liquefication

The process of cooling gas to -162oC, reducing its volume by 600 fold over the gas volume at standard conditions.

Allocation

The process of determining ownership of hydrocarbons delivered to the meter or LACT unit on a lease.

Cokriging

The process of estimating a regionalized variable from two or more variables by using a linear combination of weights obtained from models of spatial autocorrelation and cross-correlation. Cokriging is the multivariate version of kriging.

Diagenesis

The process of forming a sedimentary rock from the clastic grains. May also be in conjunction with several geochemical processes such as cementation reactions and chemical dissolution.

Fractionation

The process of separating natural gas into component parts or fractions such as propane, butane, ethane, etc.

Allowable

The production limit set on a specific well by a government regulatory body. Rarely seen.

Gasification

The production of gas from liquid or solid fuels.

Drift diameter

The published drift diameter for a pipe that describes the diameter of a tool that can pass through the pipe when the pipe is vertical (no doglegs).

Blind ram

The ram sections in a BOP that are used to close against each other and isolate the well when no pipe is in the well.

Diffusion

The random scattering of particles due to kinetic energy of the particles. Affected by viscosity, density and temperature.

Decay rate

The rate at which a population of radioactive atoms decays into stable daughter atoms. Rate expressed in half-life of the parent isotope.

Fluid loss

The rate of loss of liquids to the formations from the fluid being circulated through the wellbore.

Closing ratio

The ratio between the pressure in the hole and the operating-piston pressure needed to close the rams on a given BOP design against a particular well head pressure.

Compression ratio

The ratio of the absolute outlet pressure of a compressor to the absolute inlet pressure.

Anode corrosion efficiency

The ratio of the mass loss of actual corrosion of an anode to the theoretical corrosion mass loss calculated from the quantity of electricity that has passed between the anode and the cathode using Faraday's law (from NACE).

Acquisition log

The raw, real time recording of the data, later formed into a digital or playback log.

Absolute pressure

The reading of gauge pressure plus the atmospheric pressure.

Deliverability

The tested and proved ability of a well to produce.

Fine texture

The texture exhibited by clay, sandy clay, silty clay, clay loam, and silty clay loam soils. A soil containing large quantities of these textural classes.

Coarse fragments

The texture exhibited by sands, loamy sands, and sandy loams-except very fine, sandy loam. A soil containing large quantities of these textural classes.

Absolute open flow potential

The theoretical maximum flow that a well could deliver with a zero back pressure at the middle of the perforations. Abbreviated AOFP.

Effective wellbore radius

The theoretical radius of a wellbore that would flow the same rate as a wellbore with a fracture. Effective wellbore radius is a comparison of flow improvement related back to physical radius.

Feet of pay

The thickness of a pay zone or formation, usually the gross (total) thickness.

Casing coupling

The threaded connection, almost always upset to the outside.

Cement pump time

The time after mixing of the cement slurry before the cement becomes so viscous that it cannot be pumped.

Exchange acidity

The titratable hydrogen and aluminum that can be replaced from the adsorption complex by a neutral salt solution. Usually expressed as milliequivalents per 100 grams of soil. Acidity in a soil is primarily the result of hydrogen ions (H+), aluminum ions (AI+3), and aluminum mono and di-hydroxide ions [AI(OH)+2 and AI(OH)2+1, respectively]. Because they have a positive electrical charge these ions participate in cation exchange reactions, and because they cause soil acidity they are called exchangeable acids. Exchangeable acidity is therefore the number of meq/100 grams of soil which consist of hydrogen, aluminum, and aluminum mono and di-hydroxide ions. The remainder of the cation change capacity would consist of exchangeable bases such as sodium, potassium, calcium, and magnesium. The role of aluminum ions in acidity is described in the definition of reserve acidity.

Back up wrench

The tool that keeps the pipe string from rotating while a joint is made up. Also known as a back-up tong.

Fishing tool

The tools that can capture a lost item (a fish) in a well.

Gross acres

The total acres in which the company owns an interest.

Exchange capacity

The total charge of the adsorption complex active in the adsorption of ions.

Dry gross heating value

The total energy transferred as heat in an ideal combustion reaction at standard temperature and pressure in which all water formed appears as a liquid.

Gross pay

The total thickness of the pay zone, whether or not it is productive.

Acoustic travel time

The total time required for an acoustic wave to travel through a substance.

Downstream

The transport, refining and product making part of the oil business.

Cold/ chemical treating

The treating of an emulsion with chemicals to break an emulsion without resorting to the application of heat.

API Unit

The unit of radioactivity used for natural gamma-ray logs.

Aperture

The unobstructed opening size diameter, length and width, or other shape factor.

Elastic limit

The upper range of elasticity, just before the body is permanently deformed.

Annular valve

The valve on the side of the tree that controls access to the annulus.

Acoustic impedance

The velocity of an imposed sound wave (acoustic velocity) through a rock times the density of the rock.

Annular velocity

The velocity of fluids flowing in the annulus. Important in clean-up and displacement processes.

Dip slip fault

The vertical displacement of a fault along the dip plane.

Apparent viscosity

The viscosity at a given shear rate and a given temperature.

Absolute volume

The volume a solid occupies when added to a fluid divided by its weight. m3/kg or gal/lb.

Compressibility

The volume change of a material when pressure is applied.

Gamma Ray

Uses a scintillation crystal and a photomultiplier tube to measure naturally occurring and artificially induced gamma-ray radiation. The gamma-ray radiation is a signature of the formations in a well - very useful in depth control. Used in open hole or pipe and also used to spot changes in radiation (NORM scale) and radioactive tracers. Abbreviated GR.

Casing inspection log

Uses eddy currents in a magnetic field to estimate casing thickness and anomalies.

Gravel pack evaluation tool

Uses porosity, density and/or tracer tools to determine presence of gravel and placement of gravel type between the screen and the hole or casing.

Annular flow

Using the annulus as the flow path.

Geosteering

Using the formation data generated by a measurement while drilling system to assist in drilling a wellbore to a specific target in the formation.

Burning shoe

Usually a flat bottom mill.

Geophysicist

Usually a professional involved with application of physics to geology, e.g., seismic interpreter.

Drilling platform

Usually offshore, a platform from which wells can be drilled. It may be permanent (with legs grouted into the seafloor to depths of several hundred feet), anchored or dynamically positioned.

Bi-directional valve

Valve designed for blocking the fluid in upstream and downstream directions.

Flashing

Vaporization of water or light ends as pressure is released during production or processing.

Commercial production level

Varies with the well -- an indicator of the minimum flow rate and type of fluids that can justify completing or continuing to operate the well.

Dump flood

Various - usually allowing water to gravity feed into the annulus (without packer) or the tubing and into the formation.

Confining pressure

Various earth forces acting on the formation. Includes overburden.

Boll weevil

Various. A solid hanger or test cup in a BOP. A retrieval plug attached to drill pipe. An inexperienced worker.

Go devil

Various. A wireline cutter. A cleanout pig. A sleeve, etc.

Acoustic velocity

Velocity of an imposed sound wave through a rock.

Geologic cross section

Vertical cross section (vertical is depth and horizontal is lateral distance) between two points through a rock section.

Flow

Very simply, movement of a fluid.

Edge Water

Water at the sides or edges of the hydrocarbon deposit. Often causes problems because the channels that deplete the fastest are the highest permeability and water production through them can be severe. These respond well to treatment if they can be isolated.

Condensed water

Water condensed from gas as it is produced. Usually fresh water.

Freshwater

Water having less than 1,000 mg/L dissolved material. Friable A consistency term pertaining to the ease of crumbling of soils.

Clay bound water

Water held in or on the surface of a clay and not free to move with other connate fluids.

Biopolymer

Water soluble polymers produced by bacterial action on carbohydrates.

Ground water

Water subject to recharge from surface water accumulation.

Artesian water

Water that is overpressured and may rise above the formation.

Absolute zero temperature

Zero point on the absolute temperature scale; equal to -273.16 degrees C, or 0 degrees K (Kelvin), or -459.69 degrees F, or 0 degrees R (Rankine). This is the point at which there is no energy (i.e., no molecular movement).

Free point constant

calculation used in the stuck pipe calculation to correct for pipe wall thickness and diameter.

Bottom plug

n cementing, the first plug pumped in cementing with the two plug system. It isolates the mud and cement slurry and allows passage of the cement slurry when the plug Òbumps or reaches the float shoe or float collar. It is hollow with a diaphragm that is ruptured by pressure.

By-product

n the context of a reaction, a byproduct is a product, sometimes undesirable, of a reaction designed to create something else.

Beating phenomenon

phenomenon occurs when two harmonic waves of slightly different frequencies are impressed on a body. They are a periodic variation in vibration at a frequency that is the difference between to two frequencies.

Accomodation

place where personnel spend their off-duty time on a rig.

Decommission

remove equipment from service.

Gathering line

the flow line from the well to the separator or tank battery.