Drilling Fluids
agglomeration or aggregation
The formation of groups or clusters of particles (aggregates) in a fluid. This process results in drastic reductions in plastic viscosity, yield point and gel strength.
anode
The half of a battery that is positively charged and to which anions migrate by electrostatic attraction.
accretion
The mechanism by which partially hydrated cuttings stick to parts of the bottomhole assembly and accumulate as a compacted, layered deposit.
Blaine fineness
The particle size or fineness of a cement in cm2/g or m2/kg, usually determined from air permeability tests using a device known as a Blaine permeameter.
biodegradation
The process by which complex molecules are broken down by micro-organisms to produce simpler compounds.
Bearden units of consistency or Bc
The pumpability or consistency of a slurry, measured in Bearden units of consistency, a dimensionless quantity with no direct conversion factor to more common units of viscosity
base exchange
The quantity of positively charged ions (cations) that a clay mineral or similar material can accommodate on its negatively charged surface, expressed as milli-ion equivalent per 100 g, or more commonly as milliequivalent (meq) per 100 g.
A volume of 350 cm3 or 42 US gallons.
What volume represents a barrel equivalent?
The filtrate volume is doubled.
What woul be the result of using a half-sized cell for an API fluid test?
acidity
A chemical property of an aqueous system that implies that there are more hydrogen ions (H+) in the system, or a potential to produce more hydrogen ions, than there are hydroxyl ions (OH-), or potential to produce hydroxyl ions.
alkalinity or Pf or Pm
A chemical property of an aqueous system that implies that there are more hydroxyl ions (OH-) in the system, or a potential to produce more hydroxyl ions, than there are hydrogen ions (H+), or potential to produce hydrogen ions.
bentonite
A clay mineral that is composed principally of three-layer clays, such as montmorillonite, and widely used as a mud additive for viscosity and filtration control.
bicarbonate or bicarb
A compound containing the bicarbonate ion [HCOO-]. The term is commonly used to refer to the ion itself.
active sulfide
A compound of sulfur that contains the S-2 ion. These compounds can be generated from soluble iron sulfide minerals or from sulfate-reducing bacteria. This term is used to denote compounds that revert to the highly toxic H2S gas when acidified with 2-molar citric acid solution, as opposed to inert sulfide, which is stable.
base slurry
A conventional cement slurry used as the cementitious component of a foamed cement slurry.
acrylamido methyl propane sulfonate polymer
A copolymer of 2-acrylamido-2methyl propane sulfonate and acrylamide. These polymers are highly water-soluble anionic additives designed for high-salinity and high-temperature water-mud applications.
bland coring fluid
A coring fluid formulated with components that are not likely to alter the wettability in the pores of the rock sample and that has low dynamic filtration characteristics.
barite
A dense mineral comprising barium sulfate [BaSO4].
barite
A dense sulfate mineral that can occur in a variety of rocks, including limestone and sandstone, with a range of accessory minerals, such as quartz, chert, dolomite, calcite, siderite and metal sulfides.
air-cut mud or gas-cut mud
A drilling fluid (or mud) that has gas (air or natural gas) bubbles in it, resulting in a lower bulk, unpressurized density compared with a mud not cut by gas.
asphaltic mud additive
A group of high-viscosity or solid hydrocarbons obtained from naturally occurring deposits or from the residue of petroleum refining, commonly used as additives for oil-base and water-base muds.
aromatic hydrocarbon
A type of compound containing hydrogen and carbon atoms arranged in a symmetrical 6-carbon ring structure with single (C-C) and double (C=C) bonds alternating around the ring.
amines
A group of organic chemicals that are analogs of ammonia (NH3), in which either one, two or three hydrogen atoms of ammonia are replaced by organic radicals. These compounds are organic bases (mildly alkaline) and react with acids to form nitrogenous, organic salts. These compounds are made from fatty acids are emulsifiers and oil-wetting agents for oilfield chemicals.
amides
A group of organic chemicals with the general formula RCO-NH2 formed from reactions of ammonia (NH3) and a carboxylic acid, RCOO-H+. These compunds are emulsifiers and surfactants, many of which are made from fatty acids.
bioassay
A laboratory test or other assessment utilizing a living organism, such as mysid shrimp, to determine the effect of a condition to which the organism is exposed.
abrasion test
A laboratory test to evaluate drilling-grade weighting material for potential abrasiveness.
acrylamide acrylate polymer, also called partially hydrolized polyacrilamide
A linear copolymer of acrylate (anionic) and acrylamide (nonionic) monomers.
acrilamide polymer
A linear, nonionic polymer made of acrylamide monomers.
bond log
A log that uses the variations in amplitude of an acoustic signal traveling down the casing wall between a transmitter and receiver to determine the quality of cement bond on the exterior casing wall.
alkalinity test
A measure of the total amount of hydroxyl ions in a solution as determined by titration with standardized acid. This test is a well-known water-analysis procedure to estimate hydroxyl, carbonate ion and bicarbonate ion concentrations.
antifoam or antifoam agent
A mud additive used to lower interfacial tension so that trapped gas will readily escape from mud.
attapulgite
A needle-like clay mineral composed of magnesium-aluminum silicate. Major deposits occur naturally in Georgia, USA. This mineral can be used in saltwater mud to provide low-shear rate viscosity for lifting cuttings out of the annulus and for barite suspension.
anion
A negatively charged ion. Clay surfaces, groups on polymer chains, colloids and other materials have distinct, negatively charged areas or ions.
biopolymer
A polymer produced by a strain of bacteria.
anode
A protective device to prevent electrolytic corrosion. These devices (often made of Mg or Al metal) are sacrificed intentionally to protect a steel system, such as a buried pipeline or offshore platform.
alum
A series of double salts of aluminum sulfate and potassium sulfate with the formula Al2(SO4)3·K2SO4·nH2O. This compound is used as a colloidal flocculant in wastewater cleanup.
bentonite equivalent
A term used to express the results of the methylene blue test, which determines the amount of clay-like materials in a water-base drilling fluid based on the amount of methylene blue dye absorbed by the sample.
aniline point test
A test to evaluate base oils that are used in oil mud. The test indicates if an oil is likely to damage elastomers (rubber compounds) that come in contact with the oil.
API fluid loss test
A test to measure static filtration behavior of water mud at ambient (room) temperature and 100-psi differential pressure, usually performed according to specifications set by API, using a static filter press.
American Petroleum Institute (API)
A trade association founded in 1919 with offices in Washington, DC, USA. Among its long-term endeavors is the development of standardized testing procedures for drilling equipment, drilling fluids and cements, called API Recommended Practices ("RPs").
Bingham plastic model
A two-parameter rheological model widely used in the drilling fluids industry to describe flow characteristics of many types of muds. Fluids obeying this model exhibit a linear shear-stress, shear-rate behavior after an initial shear stress threshold has been reached.
bichromate salt
A type of salt in which chromium atoms are in the plus-7 valence state, such as potassium dichromate, K2Cr2O7.
bactericide or biocide or preservative
An additive that kills bacteria, which are commonly used in water muds containing natural starches and gums that are especially vulnerable to bacterial attack.
balanced activity oil mud
An oil-base mud in which the activity, or vapor pressure, of the brine phase is balanced with that of the formations drilled.
acetic acid
An organic acid used in oil- and gas-well stimulation treatments. Less corrosive than the commonly used hydrochloric acid, treatments using this acid can be more easily inhibited or retarded for treatments of long duration.
Beneficiation
Chemical treatment or mechanical processes that improve a mineral or ore for its designed use.
barite
Commonly used as a weighting agent for all types of drilling fluids, these minerals are mined in many areas worldwide and shipped as ore to grinding plants in strategic locations, where API specifies grinding to a particle size of 3 to74 microns.
Octyl alcohol, aluminum stearate, various glycols, silicones and sulfonated hydrocarbons
Give some examples of defoamers
aggregate
Group or cluster of particles in a fluid.
anode
Half of an electrolytic corrosion cell in metal is called the "anode," from which metal dissolves, often leaving pits. The anode is the part of a corrosion cell in which oxidation occurs.
Abrasiveness is quantified by the rate of weight loss, reported in units of mg/min.
How is abrasiveness quatified?
The apparent viscosity (AV) is one-half of the dial reading at 600 rpm (1022 sec-1 shear rate) using a direct-indicating, rotational viscometer.
How is the apparent viscosity calculated in the Bingham plastic rheology model?
a polysaccharide biopolymer known as XC polymer
In drilling and completion operations, what is the most common type of biopolymer?
In the oil field, absolute volume is typically given in units of gallons per pound (gal/lbm) or cubic meters per kilogram (m3/kg).
In the oilfield, what are the typical units of absolute volume?
acrylate polymer polyacrylate
Linear, anionic polymer made from the monomer acrylic acid.
black list
List of products considered unsuitable by the Oslo and Paris Commission (OSPAR) for discharge, including mercury, cadmium and 'persistent oils and hydrocarbons of a petroleum origin.'
acyclic or aliphatic compound
One of a group of organic compounds of carbon (C) and hydrogen (H) in which the carbon atoms have linear, branched chain (open), or both types of structures.
API cement
One of several classes of cement manufactured to the specifications of the American Petroleum Institute (API) Specification 10A.
aromatic content test
One of two quantitative analysis procedures for measuring aromatic content of base oils for use in oil mud as proscribed by the API.
acid
Pertaining to an aqueous solution, such as a water-base drilling fluid, which has more hydrogen ions (H+) than hydroxyl ions (OH-) and pH less than 7.
alkaline
Pertaining to an aqueous solution, such as a water-base drilling fluid, which has more hydroxyl ions (OH-) than hydrogen ions (H+) and pH greater than 7.
anaerobic
Pertaining to systems, reactions or life processes of species, such as bacteria, in which atmospheric oxygen is not present or not required for survival.
activity of aqueous solutions
The escaping tendency, or vapor pressure, of water molecules in an aqueous solution compared with that of pure water, typically abbreviated aw.
aerobic
Referring to a condition or a situation in which free oxygen exists in an environment.
aerobic
Referring to a condition or a situation or a living creature, such as a bacteria, in which oxygen is required to sustain life.
anionic
Related to negatively charged ions. These characteristics affect performance of additives and contaminants in drilling fluids, especially water muds, in which clays and polymers are used extensively.
bomb
Slang term for a type of pressure vessel.
API water
The amount of mixing water specified in API Specification 10A for specification testing of cement to meet API requirements. This amount is not intended to be a guide for mix water requirements in field applications.
BOD
The amount of oxygen consumed by biodegradation processes during a standardized test. The test usually involves degradation of organic matter in a discarded waste or an effluent.
biochemical oxygen demand
The amount of oxygen consumed by biodegradation processes during a standardized test. The test usually involves degradation of organic matter in a discarded waste or an effluent.
anhydrate
The anhydrous mineral form of calcium sulfate, CaSO4. (Gypsum, CaSO4·2H2O, is the hydrated form.) The presence of anhydrite or gypsum in rock will influence the type of mud selected for drilling the rock because when CaSO4 dissolves in a water mud, Ca+2 and SO4-2 ions are formed. Although both ions are detrimental to freshwater mud properties, Ca+2 is the more harmful of the two.
bioaccumulation or bioconcentration
The concentration of a particular substance in a living organism, possibly with harmful effects.
ASTM
The designation of a standard developed by ASTM International.
aluminum stearate
The salt of aluminum hydroxide and stearic acid (saturated C-18 fatty acid) with the formula Al(O2C18H35)3. It is a grease-like solid. When mixed with oil (for example, diesel oil) and the mixture sprayed onto the surface of a foamy water mud, it helps the gas bubbles break out of the mud.
bottomhole circulating temperature
The temperature at the bottom of a well while fluid is being circulated, abbreviated BHCT. This is the temperature used for most tests of cement slurry in a liquid state (such as thickening time and fluid loss).
bottomhole static temperature
The undisturbed temperature at the bottom of a well. After circulation and after the well is shut in, the temperature approaches this value after about 24 to 36 hours, depending on the well conditions.
Apparent viscosity
The viscosity of a fluid measured at a given shear rate at a fixed temperature.
Apparent viscosity
The viscosity of a fluid measured at the shear rate specified by API.
absolute volume
The volume a solid occupies or displaces when added to water divided by its weight, or the volume per unit mass.
barite
This compound is commonly used to add weight to drilling fluid. It is of significance to petrophysicists because excess of this compound can require a correction factor in some well log measurements.
bottomhole static temperature
This is the temperature used in most tests in which the cement slurry is required to set or is set.
abrasion test
This test measures weight loss of a specially shaped, stainless-steel mixer blade after 20 minutes at 11,000 rpm running in a laboratory-prepared mud sample.
Beneficiate
To improve a mineral or ore for its designed use through chemical treatments or mechanical processes.
Classes of API cement are A, B, C, D, E, F, G and H.
What are the different classes of API cement?
Mineral hardness, particle size and shape are the main parameters that affect abrasiveness of weighting materials.
What are the main parameters that affect abrasiveness of weighting materials?
barite
What compound is described by the chemical formula BaSO4?
acrylamido methyl propane sulfonate polymer
What does AMPS stand for?
Abbreviation for American Petroleum Institute
What does API stand for?
Until 2001, ASTM was an acronym for the American Society for Testing and Materials, but the organization changed its name to ASTM International to reflect its global scope as a forum for development of international voluntary consensus standards
What does ASTM stand for?
An abbreviation for oilfield barrel, a volume of 42 US gallons [6.16 m3].
What does BBL stand for?
bottomhole circulating temperature
What does BHCT stand for?
biochemical oxygen demand
What does BOD stand for?
Bearden units of consistency
What does Bc stand for?
7.1 sq.in.
What is the filtering area of the filter medium for an API fluid loss test.
Pure barium sulfate has a specific gravity of 4.50 g/cm3, but drilling-grade barite is expected to have a specific gravity of at least 4.20 g/cm3 to meet API specifications.
What is the specific gravity of barite?
Yield Point (YP)
What is the threshold stress called in the Bingham plastic model?
Shear Rate
What needs to be defined in order for a viscosity measurement to be meaningful?
Plastic viscosity (PV)
What parameter describes the slope of the line describing the shear-stress, shear-rate relationship in the Bingham plastic model?
Fineness of a cement affects the hydration rate (setting) and the requirements for the amounts of water, retarder and dispersant.
What parameters are affected by the fineness of a cement?
Apparent viscosity
With respect to drilling fluids, what does AV stand for?