Geology

basin

1. a local depression in the earth's crust in which sediments can accumulate to form thick sequences of sedimentary rock. 2.the area drained by a stream and its tributaries. 3.a geologic structure in which strata are inclined toward a common center.

apron

A body of coarse, poorly sorted sediments formed by the coalescence of alluvial or detrital fans. Can also be formed by the coalescence of submarine debris fans along the base of the continental slope.

absolute permeability

A measure of the ability of a single fluid(such as water, gas or oil) to flow through a rock formation when the formation is totally filled with that fluid. The permeability measure of a rock filled with a single fluid is different from the permeability measure of the same rock filled with two or more fluids.

calcite

Another term for calcium carbonate

barefoot completion

Give a synonym for open-hole completion.

alkane

Give a synonym for paraffin

American Association of Petroleum Geologists

What does AAPG stand for?

authority for expenditure

What does AFE stand for?

coal

a carbonaceous, rocklike material that forms from the remains of plants that were subjected to biochemical processes, intense pressure, and high temperatures. It is used as fuel.

calcium sulfate

a chemical compound of calcium, sulfur, and oxygen, CaSO4

carbonation

a chemical reaction that produces carbonates. In geology, a form of chemical weathering in which a mineral reacts with carbon dioxide ( in solution as carbonic acid) to form a carbonate mineral.

breccia

a conglomerate rock composed largely of angular fragments greater than 2 millimeters in diameter

atoll

a coral island consisting of a reef surrounding a lagoon

compaction

a decrease in the volume of a stratum due to pressure exerted by overlying strata, evaporation of water, or other causes.

caprock

a disklike plate of anhydrite, gypsum, limestone, or sulfur overlying most salt domes in the Gulf Coast region. Impermeable rock overlying an oil or gas reservoir that tends to prevent migration of oil or gas out of the reservoir.

adhesion

a force of attraction that causes molecules of one substance to cling to those of a different substance

asphalt

a hard brown or black material composed principally of hydrocarbons. It is insoluble in water but soluble in gasoline and can be obtained by heating some petroleums, coal tar, or lignite tar. It is used for paving and roofing and in paints.

borehole

a hole made by drilling or boring a wellbore.

alluvial fan

a large sloping sedimentary deposit at the mouth of a canyon. Especially in arid climates, composed of gravel and sand.

chromatography

a method of separating a solution of closely related compounds by allowing it to seep through an adsorbent so that each compound is adsorbed in a separate layer.

carbonate mud

a mud that forms on the seafloor by the accumulation of calcite particles. It may eventually become limestone.

cavern

a natural cavity in the earth's crust that is large enough to permit human entry. Commonly formed in limestone by groundwater leaching.

butane

a paraffin hydrocarbon, C4H10

biofacies

a part of a stratigraphic unit that differs in its fossil fauna and flora from the rest of the unit.

aquifer

a permeable body of rock capable of yielding groundwater to wells and springs.

capillary pressure

a pressure or adhesive force caused by the surface tension of water. This pressure causes the water to adhere more tightly to the surface of small pore spaces than to larger ones. Capillary pressure in a rock formation is comparable to the pressure of water that rises higher in a small glass capillary than it does in a larger tube.

acoustic log

a record of the measurement of porosity, done by comparing the depth to the time it takes for a sonic impulse to travel through a given length of formation. Synonym sonic logging

caliper log

a record showing variations in wellbore diameter by depth, indicating undue enlargement due to caving in, washout, or other causes.

bioherm

a reef or mound built by small organisms and their remains, such as coral, plankton, and oysters.

chert

a rock of precipitated silica whose crystalline structure is not easily discernible and that fractures conchoidally (like glass). Flint, jasper, and chat are forms of chert.

carbonate

a salt of carbonic acid. a compound containing the carbonate radical CO3

arkose

a sandstone composed largely of feldspar grains and deriving from granitic source rock.

arenite

a sandstone in which less than 15% of the total volume is silt and clay.

aeolian deposit

a sediment deposited by wind

clastic rock

a sedimentary rock composed of fragments of preexisting rocks. The principal distinction among clastics is grain size. Conglomerates, sandstones, and shales are clastic rocks

carbonate rock

a sedimentary rock composed primarily of calcium carbonate or calcium magnesium carbonate (dolomite)

aliphatic series

a series of open-chained hydrocarbons. The two major classes are the series with saturated bonds and the series with unsaturated bonds.

bed

a specific layer of earth or rock that presents a contrast to other layers of different material lying above, below, or adjacent to it.

ad valorem[və'lɔrəm] tax

a state or county tax based on the value of a property

alidade

a surveying instrument consisting of sighting device, index and reading or recording device

clay

a term used for particles smaller than 1/256 millimeter (4 microns) is size, regardless of mineral composition. A grou of hydrous aluminum silicate minerals (clay minerals) . A sediment of fine clastics

buildup test

a test in which a well is shut in for a prescribed period of time and a bottomhole pressure bomb run in the well to record the pressure. From these data and from knowledge of pressures in nearby wells, the effective drainage radius or the presence of permeability barriers or other production deterrents surrounding the wellbore can be estimated.

biotite

a type of mica that is high in magnesium and dark in color.

acoustic survey

a well-logging method in which sound impulses are generated and transmitted into the formations opposite the wellbore.

anaerobic

active in the absence of free oxygen

chromatograph

an analytical instrument that separates mixtures of substances into identifiable components by means of chromatography.

anticline

an arched, inverted-trough configuration of folded rock layers.

cash flow analysis

an economic analysis that relates investments to subsequent revenues and also makes possible a comparison between investments. It usually also includes the general plan to be used for the figuring of federal income tax on investments.

authority for expenditure

an estimate of costs prepared by a lease operator and sent to each nonoperator with a working interest for approval before work is undertaken. Normally used in connection with well drilling operations.

basalt

an extrusive igneous rock that is dense, fine grained, and often dark gray to black.

angular unconformity

an unconformity in which formations above and below are not parallel.

blowout

an uncontrolled flow of gas, oil or other well fluids into the atmosphere. This can occur when formation pressure exceeds the pressure applied to it by the column of drilling fluid. A kick warns of the possibility of a blowout.

artificial lift

any method used to raise oil to the surface through a well after reservoir pressure has declined to the point at which the well no longer produces by means of natural energy, Sucker rod pumps, gas lift, hydraulic pumps, and submersible electric pumps are the most common means of artificial lift.

anaerobic bacteria

bacteria that do not require free oxygen to live or that are not destroyed by its absence. Under certain conditions, anaerobic bacteria can cause scale to form in water handling facilities in oilfields or hydrogen sulfide to be produced from sulfates.

aerobic bacteria

bacteria that require free oxygen for their life processes. Aerobic bacteria can produce slime or scum, which accumulates on metal surfaces, causing oxygen-concentration cell corrosion.

calcareous

containing or composed largely of calcium carbonate, or calcite CaSO3.

capitalized

deducted from income over the years of useful life of an item purchased

andesite

finely crystalline, generally light-colored extrusive igneous rock composed largely of plagioclase feldspar with smaller amounts of dark colored minerals

aromatic hydrocarbons

hydrocarbons derived from or containing a benzene ring. Many have an odor. Single-ring " " are the benzene series (benzene, ethylbenzenes, an toluene). " "also include naphthalene and anthracene.

aliphatic hydrocarbons

hydrocarbons that have a straight chain of carbon atoms.

biochemical

involving chemical reactions in living organisms.

bottomhole money

money paid by a contributing company in exchange for the information received from the drilling on the completion of a well to a specified depth, regardless of whether the well is a producer of oil or gas or is a dry hole.

associated gas

natural gas that overlies and contacts crude oil in a reservoir. Also called free gas.

carbonic

of or relating to carbon, carbonic acid, or carbon dioxide.

asphaltic material

one of a group of solid, liquid, or semisolid materials that are predominantly mixtures of heavy hydrocarbons and their nonmetallic derivatives and are obtained either from natural bituminous deposits or from the residues of petroleum refining.

asphaltic crude

petroleum with a high proportion of naphthenic compounds, which leave relatively high proportions of asphaltic residue when refined

biogenic

produced by living organisms

biotic

relating to life, biologic; relating to the actions of living organisms.

aerobic

requiring free atmospheric oxygen for normal activity

clastic texture

rock texture in which individual rock, mineral, or organic fragments are cemented together by an amorphous or crystalline mineral such as calcite.

clastics

sediments formed by the breakdown of large rock masses by climatological processes, physical or chemical. The rocks formed from these sediments.

bedrock

solid rock exposed at the surface or just beneath the soil.

analog

something that is similar to something else. Representing a range of numbers by directly measurable variable quantities, such as voltages.

compaction anticline

synonym for draped anticline

backshore

that part of the seashore that lies between high-tide and storm-flood level.

adsorption

the adhesion of a thin film of gas or liquid to the surface of a solid

allowable

the amount of oil or gas that can be produced legally from a well per unit of time. In a state using proration, this figure is established monthly by its conservation agency.

cohesion

the attractive force between the same kinds of molecules.

brecciation

the breaking of solid rock into coarse, angular fragments by faulting or crushing.

anhydrite

the common name for anhydrous calcium sulfate, CaSO4.

cementation

the crystallization or precipitation of soluble minerals in the pore spaces between clastic particles, causing them to become consolidated into sedimentary rock. Precipitation of a binding material around grains or minerals in rocks.

backbarrier complex

the depositional environments associated with a shallow lagoon shoreward from a coastal barrier island. These environments are highly variable and may include tidal channels, salt marshes, shell reefs, and mangrove swamps, among others.

cash flow

the difference between inflow and outflow of funds over a period of time. This can be positive (profit) or negative (losses)

Archie's Equation

the formula for evaluating the quantity of hydrocarbons in a formation. The form of the equation depends on its specific use.

bed load

the gravel and coarse sand that are rolled and bounced along the bottom of a flowing stream.

bottomset bed

the part of a marine delta that lies farthest from shore. It consists of silt and clay extending well out from the toe of the steep delta face. Such beds grow slowly, out of reach of the effects of river current and wave action.

absolute porosity

the percentage of the total bulk volume of a rock sample that is composed of pore spaces or voids.

acoustic well logging

the process of recording the acoustic characteristics of subsurface formations, based on the time required for a sound wave to travel a specific distance through rock. The rate of travel depends on the composition of the formation, its porosity, and its fluid content. Synonym sonic logging

capillarity

the rise and fall of liquids in small diameter tubes or tubelike spaces, caused by the combined action of surface tension (cohesion) and wetting (adhesion)

bedding plane

the surface that separates each successive layer of a stratified rock from the preceding layer. It is here that minor changes in sediments or depositional conditions can be observed.

catastrophism

the theory that the earth's landforms assumed their present configuration in a brief episode at the beginning of geologic history-possibly in a single great catastrophic event- and have remained relatively unchanged since that time.

biosphere

the thin zone of air, water, and soil where all terrestrial life exists.

Cenozoic era

the time period from 65 million years ago until the present. It is marked by rapid evolution of mammals and birds, flowering plants, grasses, and shrubs, and little change in invertebrates.

biomass

the total mass of living organisms per unit volume per unit of time

carbonize

to convert into carbon or a carbonic residue.

accrete

to enlarge by the addition of external parts or particles

complete a well

to finish work on a well and bring it to productive status

acidize

to treat oil-bearing limestone or other formations with acid for the purpose of increasing production

American Association of Petroleum Geologists

what does AAPG stand for?