Glossary of Oil and Gas Terms

Abandon    (1) The proper plugging and abandoning of a well in compliance with all applicable regulations, and the cleaning up of the wellsite to the satisfaction of any governmental body having jurisdiction with respect thereto and to the reasonable satisfaction of the operator.(2) To cease efforts to find or produce from a well or field.(3) To plug a well completion and salvage material and equipment.    
Abatement     (1) The act or process of reducing the intensity of pollution.(2) The use of some method of abating pollution.   
American Petroleum Institute (API)    The American Petroleum Institute is the primary trade association representing the oil and natural gas industry in the United States.   
Annulus    The space between: (1) The casing and the wall of the borehole.(2) Two strings of casing.(3) Tubing and casing.   
API    American Petroleum Institute   
Api County Code     An indicator developed by the American Petroleum Institute (API) to identify areas such as counties and other subdivision areas identified within state boundaries. Defined by API Bulletin D12A, as amended. This code becomes a part of the API Well Number.    
Api State Code     The indicator assigned to a state, as defined in API Bulletin D12A, as amended. This code is a part of the API Well Number (The Api State Code for Colorado is 05).    
Api Well Number     A well identifier assigned as defined in API (American Petroleum Institute) Bulletin D12A, as amended. The API Well Numbers are assigned by the appropriate state or federal regulatory agency.    
Appraisal Well     A well drilled as part of an appraisal drilling program which is carried out to determine the physical extent, reserves and likely production rate of a field.   
Associated Gas    A well drilled as part of an appraisal drilling program which is carried out to determine the physical extent, reserves and likely production rate of a field.   
Barrel    A unit of volume measurement used for petroleum and its products (7.3 barrels = 1 ton: 6.29 barrels = 1 cubic meter).   
bbl    One barrel of oil; 1 barrel = 35 Imperial gallons (approx.), or 159 liters (approx.); 7.5 barrels = 1 ton (approx.); 6.29 barrels = 1 cubic meter.   
bcf    Billion cubic feet; 1 bcf = 0.83 million tons of oil equivalent.   
bcm    Billion cubic meters (1 cubic meter = 35.31 cubic feet).   
Block    An acreage sub-division measuring approximately 10 x 20 kms, forming part of a quadrant. e.g. Block 9/13 is the 13th block in Quadrant 9.   
blow-down     Condensate and gas is produced simultaneously from the outset of production.   
Blow-out     When well pressure exceeds the ability of the wellhead valves to control it. Oil and gas "blow wild" at the surface.   
Blow-out preventers (BOPs)    Are high pressure wellhead valves, designed to shut off the uncontrolled flow of hydrocarbons.   
BOP    See blow-out preventers   
Borehole     The hole as drilled by the drill bit.   
Bradenhead    A casinghead.   
Bradenhead Test       
Casing    Pipe cemented in the well to seal off formation fluids or keep the hole from caving in.    
Casing string    The steel tubing that lines a well after it has been drilled. It is formed from sections of steel tube screwed together.   
Central estimate    A range of exploration drilling scenarios from which the following activity levels, based on recent historical experience, are adopted as the central estimates.   
Christmas tree    The assembly of fittings and valves on the top of the casing which control the production rate of oil.   
COGCC    Colorado Oil and Gas Conservation Commission   
COGIS    Colorado Oil and Gas Information Systems   
Commercial field     An oil and/or gas field judged to be capable of producing enough net income to make it worth developing.   
Completion    The installation of permanent wellhead equipment for the production of oil and gas.   
Condensate     Hydrocarbons which are in the gaseous state under reservoir conditions and which become liquid when temperature or pressure is reduced. A mixture of pentanes and higher hydrocarbons.   
Coring    Taking rock samples from a well by means of a special tool -- a "core barrel".   
Crane barge    A large barge, capable of lifting heavy equipment onto offshore platforms. Also known as a "derrick barge".   
Crude Oil     Liquid petroleum as it comes out of the ground as distinguished from refined oils manufactured out of it.    
Cubic foot    A standard unit used to measure quantity of gas (at atmospheric pressure); 1 cubic foot = 0.0283 cubic meters.   
Cuttings    Rock chips cut from the formation by the drill bit, and brought to the surface with the mud. Used by geologists to obtain formation data.   
Deepen    To increase the distance below a specified reference datum.   
Derrick    The tower-like structure that houses most of the drilling controls.   
Development phase     The phase in which a proven oil or gas field is brought into production by drilling production (development) wells.   
Drill    (1)To bore a hole, Also see Drilling(2)An implement with cutting edges used to bore holes.   
Drilling    The using of a rig and crew for the drilling, suspension, completion, production testing, capping, plugging and abandoning, deepening, plugging back, sidetracking, redrilling or reconditioning of a well (except routine cleanout and pump or rod pulling operations) or the converting of a well to a source, injection, observation, or producing well, and including stratigraphic tests. Also includes any related environmental studies. Associated costs include completion costs but do not include equipping costs.   
Drilling rig    A drilling unit that is not permanently fixed to the seabed, e.g. a drillship, a semi-submersible or a jack-up unit. Also means the derrick and its associated machinery.   
Dry Gas    Natural gas composed mainly of methane with only minor amounts of ethane, propane and butane and little or no heavier hydrocarbons in the gasoline range.   
Dry hole    A well which has proved to be non-productive.   
E&A    Abbreviation for exploration and appraisal.   
E&P    Abbreviation for exploration and production.   
Enhanced oil recovery    A process whereby oil is recovered other than by the natural pressure in a reservoir.   
Exploration drilling    Drilling carried out to determine whether hydrocarbons are present in a particular area or structure.   
Exploration phase    The phase of operations which covers the search for oil or gas by carrying out detailed geological and geophysical surveys followed up where appropriate by exploratory drilling.   
Exploration well    A well drilled in an unproven area. Also known as a "wildcat well".   
Farm in    When a company acquires an interest in a block by taking over all or part of the financial commitment for drilling an exploration well.   
Field    A geographical area under which an oil or gas reservoir lies.   
Fishing    Retrieving objects from the borehole, such as a broken drillstring, or tools.   
Formation pressure    The pressure at the bottom of a well when it is shut in at the wellhead.   
Formation water    Salt water underlying gas and oil in the formation.   
Fracturing    A method of breaking down a formation by pumping fluid at very high pressures. The objective is to increase production rates from a reservoir.   
G    Gas.   
G/C    Gas Condensate.   
Gas field     A field containing natural gas but no oil.   
Gas injection     The process whereby separated associated gas is pumped back into a reservoir for conservation purposes or to maintain the reservoir pressure.   
Gas/oil ratio     The volume of gas at atmospheric pressure produced per unit of oil produced.   
Geographic Information Systems(GIS)     A computer system capable of assembling, storing, manipulating, and displaying geographically referenced information.   
GIS     See: Geographic Information Systems   
Hydrocarbon    A compound containing only the elements hydrogen and carbon. May exist as a solid, a liquid or a gas. The term is mainly used in a catch-all sense for oil, gas and condensate.   
Idle Producing       
Injection well     A well used for pumping water or gas into the reservoir.   
Jacket    The lower section, or "legs", of an offshore platform.   
Kick     A well is said to "kick" if the formation pressure exceeds the pressure exerted by the mud column.   
Lay barge     A barge that is specially equipped to lay submarine pipelines.   
Liquefied natural gas (LNG)    Oilfield or naturally occurring gas, chiefly methane, liquefied for transportation.   
Liquefied petroleum gas (LPG)     Light hydrocarbon material, gaseous at atmospheric temperature and pressure, held in the liquid state by pressure to facilitate storage, transport and handling. Commercial liquefied gas consists essentially of either propane or butane, or mixtures thereof.   
mboe    Million Barrels Oil Equivalent.   
Mechanical Integrity Test     The act of setting a packer or retrievable bridge plug above the perforations in a wellbore and applying pressure to the annulus in order to ensure soundness of the casing.   
Metric ton     Equivalent to 1000 kilos, 2204.61 lbs.; 7.5 barrels.   
MIT    Mechanical Integrity Test   
mmcfd    Millions of cubic feet per day (of gas).   
Moonpool    An aperture in the center of a drillship or semi-submersible drilling rig, through which drilling and diving operations can be conducted.   
Mud    A mixture of base substance and additives used to lubricate the drill bit and to counteract the natural pressure of the formation.   
Natural gas    Gas, occurring naturally, and often found in association with crude petroleum.   
Natural Gas Policy Act Of 1978    Enacted on November 9, 1978 and became effective December 1, 1978. The Act has been amended, and it replaced or amended the Natural Gas Act. Refer to 15USC 3301-3432.   
NGLs    Natural gas liquids. Liquid hydrocarbons found in association with natural gas.   
Ngpa     SEE: Natural Gas Policy Act of 1978.   
O    Oil.   
O&G    Oil and Gas.   
Oil    A mixture of liquid hydrocarbons of different molecular weights.   
Oil field    A geographic area under which an oil reservoir lies.   
Oil in place    An estimated measure of the total amount of oil contained in a reservoir, and, as such, a higher figure than the estimated recoverable reserves of oil.   
Operator    The company that has legal authority to drill wells and undertake the production of hydrocarbons that are found. The Operator is often part of a consortium and acts on behalf of this consortium.   
Payzone    Rock in which oil and gas are found in exploitable quantities.   
Permeability    The property of a formation which quantifies the flow of a fluid through the pore spaces and into the wellbore.   
Petroleum    A generic name for hydrocarbons, including crude oil, natural gas liquids, natural gas and their products.   
Platform    An offshore structure that is permanently fixed to the seabed.   
Porosity    The percentage of void in a porous rock compared to the solid formation.   
Possible reserves    Those reserves which at present cannot be regarded as ‘probable’ but are estimated to have a significant but less than 50% chance of being technically and economically producible.   
Primary recovery     Recovery of oil or gas from a reservoir purely by using the natural pressure in the reservoir to force the oil or gas out.   
Probable reserves    Those reserves which are not yet proven but which are estimated to have a better than 50% chance of being technically and economically producible.   
Proven field    An oil and/or gas field whose physical extent and estimated reserves have been determined.   
Proven reserves    Those reserves which on the available evidence are virtually certain to be technically and economically producible (i.e. having a better than 90% chance of being produced).   
Recomplete    An operation involving any of the following: (1) Deepening from one zone to another zone.(2) Completing well in an additional zone.(3) Plugging back from one zone to another zone.(4) Sidetracking to purposely change the location of the bottom of the well, but not including sidetracking for the sole purpose of bypassing obstructions in the borehole.(5) Conversion of a service well to an oil or gas well in a different zone.(6) Conversion of an oil or gas well to a service well in a different zone.   
Recoverable reserves    That proportion of the oil and/gas in a reservoir that can be removed using currently available techniques.   
Recovery factor    That proportion of the oil and/gas in a reservoir that can be removed using currently available techniques.   
Reenter    To enter a previously abandoned well.   
Reservoir    The underground formation where oil and gas has accumulated. It consists of a porous rock to hold the oil or gas, and a cap rock that prevents its escape.   
Riser (drilling)    A pipe between a seabed BOP and a floating drilling rig.   
Riser (production)    The section of pipework that joins a seabed wellhead to the Christmas tree.   
Roughneck     Drill crew members who work on the derrick floor, screwing together the sections of drillpipe when running or pulling a drillstring.   
Roustabout    Drill crew members who handle the loading and unloading of equipment and assist in general operations around the rig.   
Royalty payment    The cash or kind paid to the owner of mineral rights.   
Secondary recovery     Recovery of oil or gas from a reservoir by artificially maintaining or enhancing the reservoir pressure by injecting gas, water or other substances into the reservoir rock.   
Shut In Well    A well which is capable of producing but is not presently producing. Reasons for a well being shut in may be lack of equipment, market or other.    
Shutdown    A production hiatus during which the platform ceases to produce while essential maintenance work is undertaken.   
SI/TA    Shut In /Temporarily Abandoned   
Sidetrack    A wellbore segment extending from a wellbore intersection along a wellbore path to a different wellbore bottomhole from any previously existing wellbore bottomholes.   
Sidetracking    The well activity of drilling a new wellbore segment from a wellbore intersection to a new wellbore bottomhole or target.   
Spud-in    The operation of drilling the first part of a new well.   
Surface Location    The location of a well or facility/measurement point.   
Surface Reclamation    A restoration of the surface as for productivity or usefulness.   
Suspended well    A well that has been capped off temporarily.   
tcf    Trillion Cubic Feet (of gas).   
Temporarily Abandoned    The act of isolating the completed interval or intervals within a wellbore from the surface by means of a cement retainer, cast iron bridge plug, cement plug, tubing and packer with tubing plug, or any combination thereof.   
Toolpusher    Second-in-command of a drilling crew under the drilling superintendent. Responsible for the day-to-day running of the rig and for ensuring that all the necessary equipment is available.   
Topsides    The superstructure of a platform.   
UIC    Underground Injection Control   
Underground Injection Control    A program required in each state by a provision of the Safe Drinking Water Act (SDWA) for the regulation of Injection Wells, including a permit system. An applicant must demonstrate that the well has no reasonable chance of adversely affecting the quality of an underground source of drinking water before a permit is issued.    
Well log    A record of geological formation penetrated during drilling, including technical details of the operation.   
Wildcat well    A well drilled in an unproven area. Also known as an "exploration well". [The term comes from exploration wells in West Texas in the 1920s. Wildcats were abundant in the locality, and those unlucky enough to be shot were hung from oil derricks.]   
Workover    Remedial work to the equipment within a well, the well pipework, or relating to attempts to increase the rate of flow.