Glossary & Unit conversion

Oil converter

Standard cubic meters

Gas converter

Thousand standard* cubic meters
Thousand standard cubic feet
Million British thermal units
Barrel Oil Equivalent

Standard = standard (ISO standard conditions (temperature = 15 degrees C. and pressure = 1.01325 bar)


BBL                        Barrel One Barrel=159 liters
BCF                       Billion Cubic Feet
BOE                       Barrels of Oil Equivalents, natural gas converted to barrels of oil equivalents
BOPD                    Barrels of Oil Per Day
T                            Metric Ton 1 ton (T) of oil = 7.2 BBL of oil.
CM                        Cubic Meter. 1000 cubic meter (CM) of gas = 6.29 BOE of gas
CF                         Cubic Feet Volume measurement. One Cubic Foot=0.028 m3
CFPD                    Cubic Feet Per Day
MBLL                    Thousand Barrels
MBOE                   Thousand Barrels of Oil Equivalents
MBOEPD              Thousand Barrels of Oil Equivalents Per Day
MBOPD                Thousand Barrels of Oil Per Day
MCF                     Thousand Cubic Feet
MCFPD                Thousand Cubic Feet Per Day
MMBLL                 Million Barrels
MMBOE                Million Barrels of Oil Equivalent
MMCF                   Million Cubic Feet
MMCFPD              Million Cubic Feet Per Day
MMSCFPD            Million Standard Cubic Feet Per Day (ref. natural or residual gas production)
TCF                      Trillion Cubic Feet


ACCUMULATION - One or more occurrences of oil or gas confirmed by tests, samples or logging.
APPRAISAL WELL - A well drilled to determine the extent and scope of a petroleum find.
ASSOCIATED GAS - Natural gas produced together with oil.

BLOWING A WELL - Opening a well to let it blow for a short period to free the well tubing or casing of accumulations of water, sand, or other deposits.
BLOWOUT - Out-of-control gas and/or oil pressure erupting from a well being drilled; a dangerous, uncontrolled eruption of gas and oil from a well; a wild well.
BLOWOUT PREVENTER - A stack or an assembly of heavy-duty valves attached to the top of the casing to control well pressure; a “Christmas tree”.
BOREHOLE - The hole in the earth made by the drill; the uncased drill hole from the surface to the bottom of the well.
BRIDGE PLUG - An expandable plug used in a well’s casing to isolate producing zones or to plug back to produce from a shallower formation; also to isolate a section of the borehole to be filled with cement when a well is plugged.

COMPLETION - To finish a well so that it is ready to produce oil or gas. After reaching total depth (T.D.), casing is run and cemented; casing is perforated opposite the producing zone, tubing is run, and control and flow valves are installed at the wellhead. Well completions vary according to the kind of well, depth, and the formation from which the well is to produce.
COMPLETION FUNDS - Completion funds are formed to invest in well completions, to finance the completing and equipping of a potentially productive well. After a well is drilled into a productive formation, there remain the costs of setting pipe, (casing the well); perforating, testing, acidizing, or fracturing the formation; and running production tubing and installing pumping equipment, separators, stock tanks, etc. The operator who drills the well may not have the financial resources to complete the well, so he may sell part or all of his interests to a completion fund. Completion funds are not as risky an investment as drilling funds, but are less certain than income funds and royalty funds.
CORE SAMPLE - A solid column of rock, usually from 2 - 4 inches in diameter, taken from the bottom of a well bore as a sample of an underground formation. Cores are also taken in geological studies of an area to determine the oil and gas prospects.
CRUDE OIL - Oil as it comes from the well head; unrefined petroleum.

DEPOSIT - An accumulation of oil or gas capable of being produced commercially.
DERRICK - A wooden or steel structure built over a well site to provide support for drilling equipment and a tall mast for raising and lowering drill pipe and casing; a drilling rig.
DEVELOPMENT WELLS - Wells drilled in an area already proved to be productive.
DISCOVERY WELL - An exploratory well that encounters a new and previously untapped petroleum deposit; a successful wildcat well. A discovery well may also open a new horizon in an established field.
DOWNHOLE - A term to describe tools, equipment, and instruments used in the well bore; also conditions or techniques applying to the well bore.
DRY GAS - A natural gas from the well free of liquid hydrocarbons; gas that has been treated to remove all liquids; pipeline gas.

EXPLORATION - A general term referring to all efforts made in the search for new deposits of oil and gas.

FLARE - (1) To burn unwanted gas through a pipe or stack (Under conservation laws, the flaring of natural gas is illegal.) (2) The flame from a flare; the pipe or the stack itself.

GAS - “Any fluid, combustible or noncombustible, which is produced in a natural state from the earth and which maintains a gaseous or rarified state at ordinary temperature and pressure conditions”. Code of Federal Regulations, Title 30, Mineral Resources, Chap. II, Geological Survey, 221.2
GAS CAP - The portion of an oil-producing reservoir occupied by free gas; in a free state above an oil zone.
GAS WELL - A well that produces natural gas which is not associated with crude oil. GEOLOGY - The science of the history of the Earth and its life as recorded in rocks.

HYDROCARBONS - Organic chemical compounds of hydrogen and carbon atoms. There are a vast number of these compounds, and they form the basis of all petroleum products. They may exist as gases, liquids, or solids. An example of each is methane, hexane, and asphalt.

INJECTION WELL - A well where gas or water is injected to give pressure support in a reservoir. By injecting gas or water (or both) the degree of recovery can be increased. As the pressure is maintained by the injection, the hydrocarbons are pushed into the production well.

JACKUP RIG - A type of installation used when drilling oil wells at sea. It is fixed to the seabed.

LEADS- Leads are possible accumulations of hydrocarbons where more geological data needs to be gathered and evaluations need to be performed before they can be called prospects, where drilling is considered to be feasible.
LICENSE - A permit to search for and produce oil and gas. Oil and natural gas assets are usually owned by the country in which the accumulation is discovered. The oil companies obtain permission from the respective country’s government to explore for and extract oil and natural gas. These permits can be called concessions, permits, production sharing agreements or licenses depending on the country in question. A license usually consists of two parts an exploration permit and a production license.
LNG (Liquefied natural gas) - Liquid dry gas, primarily methane, that has transformed to liquid form upon cooling to minus 163 °C at atmospheric pressure. One ton of LNG corresponds to approximately 1,400 cubic meters of gas. LNG is transported by special vessels.

NATURAL GAS - A mixture of hydrocarbons in gas form found in the bedrock, usually 60-95 percent methane.
NGL (Natural gas liquids) -Liquid gas that consists of three different gases ethane, propane and butane, as well as small amounts of heavy hydrocarbons. Is partially liquid at atmospheric pressure. NGL is transported by special vessels.

OFFSET WELL - (1) A well drilled on the next location to the original well. The distance form the first well to the offset well depends upon spacing regulations and whether the original well produces oil or gas. (2) A well drilled on one tract of land to prevent the drainage of oil or gas to an adjoining tract where a well is being drilled or is already producing.
OBSERVATION WELL - A well that is equipped with pressure sensors and other measurement instruments to collect additional information about a reservoir. Occurrence An accumulation of petroleum in a geological unit. Delimited by rock types, a contact surface between petroleum and water or a combination of these.
OCCURRENCE - An accumulation of petroleum in a geological unit. Delimited by rock types, a contact surface between petroleum and water or a combination of these.
OIL EQUIVALENTS (o.e.) - A volume unit used when oil, gas and NGL are to be summarized. The concept is tied to the amount of energy released upon combustion of different types of petroleum. Because oil equivalents depend on the amount of energy, it is not constant and different conversion factors are used. In “Oil Field Units”, 5,800 cubic feet of gas = 1barrel of oil equivalents. According to the Norwegian Petroleum Directorate, 1,000 standard cubic meters of gas = 1 standard cubic meter of oil equivalents.
OPERATOR - A company, which on behalf of one or more companies in a partnership, has obtained the right to explore for oil and gas in an area and develop a field for production in a commercial accumulation.

PETROLEUM - Collective term for hydrocarbons, whether they occur in solid, liquid or gas state(s).
PIPELINE GAS - Gas under sufficient pressure to enter the high-pressure gas lines of a purchaser; gas sufficiently dry so that liquid hydrocarbons - natural gasoline, butane, and other gas liquids usually present in natural gas - will not condense or drop out in the transmission lines.
POROSITY - A measure of the relative volume of void space in rock to the total rock volume. These spaces or pores are where oil and gas accumulate; therefore, a formation containing a high percentage of porosity can contain more hydrocarbons.
PROVEN RESERVES - Oil and gas which has not been produced but has been located and is recoverable. Referes to Reserves that are assessed to be >90 % probable

RESERVOIR - A porous, permeable sedimentary rock formation containing quantities of oil and/or gas enclosed or surrounded by layers of less-permeable or impervious rock; a structural trap; a stratigraphic trap.
RECOVERY FORECAST - A percentage that indicates how much of the proved, existing reserves are possible to produce.
REFINERY - A facility where crude oil is converted to refined products such as petrol, motor oil and bitumen.

SATURATION - (1) The extent to which the pore space in a formation contains hydrocarbons or connate water. (2) The extent to which gas is dissolved in the liquid hydrocarbons in a formation.
SEISMIC DATA - Seismic investigations are made to be able to describe geological structures in the bedrock. At sea, sonar signals are transmitted from the ocean surface (pings), and the echoes are captured by special measurement instruments. Used to localize occurrences of hydrocarbons.
3-D SEISMIC PROGRAM - Seismic surveys shot from surfaces to map underground stratigraphy; to profile the underlying strata in search of up-dips, down dips, faults, and other promising anomalies.

VISCOSITY - The resistance of fluid to flow. A high viscosity fluid will not flow as easily as a low viscosity fluid (Mud will not move as easily as water).

WELL - A hole drilled down to a reservoir to look for or extract oil or gas.
WELLHEAD - The equipment (outlets, valves, etc.) that is fastened to the top of a well to prevent blowout.
WELL LOGGING - Gathering and recording information about the surface formation, the nature and extent of the various downhole rock layers. Also included are records kept by the driller, the record of cuttings, core analysis drill stem tests, and electric, acoustic, and radioactivity logs. Any pertinent information about a well, written and saved, is a log - from sailing ship days.
WILDCAT - A well that is drained one or more miles from a proven well.