Converting a drilled well to a condition that can be left indefinitely without further attention and will not damage freshwater supplies, potential petroleum reservoirs or the environment.


Measure of solvency of hydrocarbon solvents.

Aero-Magnetic Surveys

Magnetometers, towed by aircraft, help to detect magnetic anomalies or to distinguish geologic features that might appear similar from seismic data alone.

Air Emissions

Waste gases, vapours and small particles released into air.

Air Gun

Air gun array is most common technique used for seismic surveying offshore. Compressed air is released from a chamber to produce shock waves in earth.

Air Injection

An enhanced recovery technique in which air is injected into hydrocarbon formation to increase reservoir pressure.

Alternative Energy

Energy, such as solar, wind, or nuclear energy, that can replace or supplement traditional fossil fuel sources, such as coal, oil, and natural gas.

Appraisal Drilling

Drilling to determine physical extent, reserves and likely production rate of a reservoir, together with properties of oil or gas

Appraisal Expenditure

Costs incurred in survey, exploitation and appraisal of licence areas not yet under development or in production.

Appraisal well

A well drilled in order to evaluate the characteristics of a field.

Artificial Lift

Any techniques, other than natural drives, for bringing oil to surface.

Associated Gas

Natural gas associated with oil accumulations, either dissolved in oil or found as a cap of free gas above oil in reservoir.


Non-self-propelled marine vessel used as cargo tankers, as equipment and supply carriers, crane platforms and support and accommodation bases in offshore drilling, and as submarine pipe-laying vessels.


Unit of volume of crude oil (approximately 159 liters) in use in the oil industry, especially in the USA and the UK.


Equipment to process or store crude oil from one or more wells.


A light aromatic hydrocarbon, which occurs naturally as a part of oil and natural gas activity. It's considered to be a non-threshold carcinogen and is an occupational and public health concern.



Petroleum in semi-solid or solid forms.

Blow-out Preventers (BOPs)

High-pressure wellhead (top of casing) valves designed to shut-off flow of hydrocarbons to prevent blowouts (accidental escapes of oil or gas from a well).

Brent blend

International marker for crude oil pricing based on a blend of North Sea crudes.

British thermal unit (BTU)

The amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit.

Cap Rock

Impervious layer which overlies a reservoir rock preventing hydrocarbons escaping.


Tightly closing a well so that hydrocarbons cannot escape.


Set of steel tubular elements used to line the inner wall of a drill hole, to consolidate it. The casing is secured by cementing the annular space between the hole wall and the casing. Each time a tubing is installed, the well diameter is reduced, so that the tubing in a well forms a telescopic assembly. The tubes have a standard length of nine meters, and are assembled by threaded sleeves.


Injection of cement into the annulus (space) between the casing and the well wall to consolidate the latter and reduced water influxes.

Centrifugal pump

A rotating pump, commonly used for large-volume oil and natural gas pipelines, that takes in fluids near the centre and accelerates them as they move to the outlet on the outer rim.

Christmas Tree

Branching series of pipes, gauges and valves on top end of each production well to control flow of oil or gas.


During Carboniferous period much of world was covered with vegetation growing in swamps. This vegetation died and became submerged under water. As decomposition took place, vegetable matter lost oxygen and hydrogen atoms, leaving a peat deposit with a high percentage of carbon. As time passed, layers of sand and mud settled from water over some of peat deposits. Pressure of these overlying layers, as well as movements of earth's crust and sometimes volcanic heat, acted to compress and harden deposits, thus producing coal.

Coalbed methane (CBM)

Natural gas generated and trapped in coal seams.

Coiled tubing

Used to carry production tubing to bottom of well.

Commercial Field

Field judged to be capable of producing sufficient net income to be worth developing.


An engine used to increase the pressure of natural gas so that it will flow more easily through a pipeline.

Concession (oil or gas)

Deed entitling holder to produce from and/or explore a stipulated tract of land following discovery of a commercial reservoir.


Hydrocarbons, usually produced with natural gas, which are liquid at normal pressure and temperature.


Liquid mixture of pentane and higher hydrocarbons

Conventional crude oil

Petroleum found in liquid form, flowing naturally or capable of being pumped without further processing or dilution.

Core-sampling (or coring)

During drilling, cylindrical samples of rock known as "core samples" are removed in order to study the characteristics of the terrain.


Crane Barge

Vessel capable of lifting heavy equipment onto / off offshore installations.

Criteria air contaminants (CAC)

Emissions of various air pollutants that affect our health and contribute to air pollution problems such as smog.

Crude oil

Unrefined oil.

Cubic Feet

Standard unit used to measure quantity of gas at atmospheric pressure

(One cubic foot = 0.0283 cubic metres).

Cumulative effects

Changes to the environment caused by an activity in combination with other past, present and reasonably foreseeable human activities.

Cumulative production

Production of oil or gas to date.

Deep-Water Discovery

An offshore discovery located in at least 200 metres of water.

Delineation Well

Drilled at a distance from a discovery well to determine physical extent, reserves and likely production rate of a new oil or gas field.


The heaviness of crude oil, indicating the proportion of large, carbon-rich molecules, generally measured in kilograms per cubic metre (kg/m3) or degrees on the American Petroleum Institute (API) gravity scale; in Western Canada oil up to 900 kg/m3 is considered light to medium crude - oil above this density is deemed as heavy oil or bitumen. scale.


Elongated pyramid of latticed steel mounted over bore hole for suspending and rotating drill pipes.

Development Expenditure

All costs including financing costs, E&A expenditures incurred in bringing a field to commercial production and is defined as tangible assets.

Development well

A well drilled in or adjacent to a proven part of a pool to optimize petroleum production.

Discovery well

An exploratory well that encounters a previously untapped oil or gas deposit.

Downstream sector

The refining and marketing sector of the petroleum industry.

Drill Bit

Located at end of drill-string cutting head is generally designed with three cone-shaped wheels tipped with hardened teeth. Drill bits used for extra-hard rock are studded with thousands of tiny industrial diamonds.

Drill Collars

Heavy pipe-sections that put weight on drill bit.

Drill Cuttings

Lifted continually to surface during drilling by a circulating-fluid system driven by a pump. To facilitate removal of cuttings, mud is constantly circulated down through drill pipe, out through nozzles in drill bit, and then up to surface through space between drill pipe and well bore through earth (diameter of bit is somewhat greater than that of pipe).

Drill Ship

Free floating mobile drilling platform used in very deep waters. Positioned by dynamic positioning.

Drilling Mud / Fluid

Mixture of base substance and additives used to lubricate drill bit and to counter act natural pressure in formation. Drilling mud provides circulation, flushing rock cuttings from bottom of well bore to surface.

Dry Gas

Or Lean gas is natural gas composed mainly of methane.

Dry hole

Any exploratory or development well that does not find commercial quantities of hydrocarbons.


Exploration and production. The "upstream" sector of the oil and gas industry.

Enhanced oil recovery (EOR)

Any method that increases oil production by using techniques or materials that are not part of normal pressure maintenance or water flooding operations. For example, natural gas can be injected into a reservoir to "enhance" or increase oil production.

Environmental Impact Assessment (EIA)

Part of project management concerned with identifying through a formal written technical evaluation likely impact (positive and negative) of a proposed development or activity on natural and man-made environment.

Environmental Management Systems (EMS)

A process that examines environmental factors and activities or processes that industry uses.

Established reserves

The portion of the discovered resource base that is estimated to be recoverable using known technology under present and anticipated economic conditions. Includes proved plus a portion of probable (usually 50 per cent).


Search for hydrocarbons by Geological and Geophysical (G&G) surveys that may be followed by exploration drilling.

Exploration Expenditure

All costs, including premium payments, associated with acquisition of new acreage, drilling of exploratory wells and other costs incurred in evaluating commercial viability of geological entities

Exploration well

A well into an area where petroleum has not been previously found or one targeted for formations above or below known reservoirs.


Transfer of part of an oil or gas interest in consideration for an agreement by transferee(s) to meet certain expenditure that would otherwise have to be undertaken by licensee(s).


Death due to work related injury / illness.

Fatality Rate

Number of fatalities per 1000 employees.


A line of fracture along which one body of rock or section of Earth's crust has been displaced relative to another


The surface area above one or more underground petroleum pools sharing the same or related infrastructure.

Flaring and venting

Flaring is burning of hydrocarbon gases for commercial or technical reasons. Venting is release of gases to atmosphere.


The controlled burning (flare) or release (vent) of natural gas that can't be processed for sale or use because of technical or economic reasons.

Flow line

Pipe, usually buried, through which oil or gas travels from the well to a processing facility.

Gas / Condensate Field

Reservoir containing both natural gas and oil, with greater proportion of gas. Condensate appears when gas in drawn from well, and its temperature and pressure change sufficiently for some of it to became liquid petroleum.

Gas Cap

In field containing both gas and oil, some gas will often collect at top of reservoir in a single deposit.

Gas Gathering System

Central collection point for offshore gas fields. Production is then piped to central processing system onshore.

Gas Injection (GI)

Associated gas is pumped back into a reservoir to maintain reservoir pressure. In this way rate of production of crude oil also can be increased.

Gas Lift

Gas from same or nearby field is mixed with oil in tubing to lessen weight of liquid column.

Gas Processing

Separation of oil and gas, and removal of impurities and NGLs from natural gas.

Gas Treatment

Removal of impurities, condensate, hydrogen sulphide and NGLs from natural gas.

Gas-to-Liquids (GTL)

The conversion of natural gas to a liquid form so that it can be transported easily. Typically, the liquid is converted back to natural gas prior to consumption.


Mixture of lighter liquid hydrocarbons used chiefly as a fuel for internal-combustion engines. Produced by fractional distillation of petroleum; by condensation or adsorption from natural gas; by thermal or catalytic decomposition of petroleum or its fractions; by hydrogenation of producer gas or coal; or by polymerisation of hydrocarbons of lower molecular weight.


Field of science concerned with origin of planet Earth, its history, its shape, materials forming it, and processes that are acting and have acted on it.


Branch of science that applies physical principles to study of planet earth.


A standard adopted by the American Petroleum Institute for measuring the density of a liquid. Gravity is expressed in degrees with lower numbers indicating heavier liquids and higher numbers indicating lighter liquids.

Greenhouse Gases

Gases that alter thermal properties of atmosphere (for example, water vapour, carbon dioxide, methane, nitrous oxide, CFCs, halons and ozone).


Object, physical effect, or a condition with potential to harm persons, property or environment

Heavy crude oil

Oil with a gravity below 28 degrees API.

Heavy Oil

Long chains of hydrogen and carbon atoms.

Horizontal drilling

Drilling a well that deviates from the vertical and travels horizontally through a producing layer.

Hot water process

A method for separating bitumen from oil sand using hot water and caustic soda, developed by Karl Clark of the Alberta Research Council.


Family of organic compounds, composed entirely of carbon and hydrogen (for example, coal, crude oil and natural gas).


Fluids cannot flow through rocks (clays, cemented sandstone or salt) where cracks

and pore spaces are very small or are blocked by mineral growth.


An unplanned event or chain of events which has or could have caused injury or illness and / or damage or loss to environment, third parties or assets.

Injection well

A well used for injecting fluids (air, steam, water, natural gas, gas liquids, surfactants, alkalines, polymers, etc.) into an underground formation for the purpose of increasing recovery efficiency.


Physical harm or damage to a person resulting from traumatic contact between body of person and an outside agency, or from exposure to environmental factors.

Injury Severity Rate

Number of days lost per one million man hours worked.

Jack-Up Rig

Mobile drilling platform with retractable legs used in shallow waters less than 100 metres deep.


Supporting (concrete base or steel legs) structure for an offshore installation.

Joint Operative Body

An agreement among working interest owners describing how a well is to be operated.


Back pressure in well from invading oil / gas / water.

Killing a well

Filling bore with drilling mud of suitable density to stop flow of oil / gas.

Lay Barge

Vessel specially equipped to lay submarine pipelines.


Right to explore for and exploit hydrocarbon reserves within a defined area.

Licence Round

Period during which Government offers and then allocates a number of specified areas (Blocks or part Blocks) within its national boundaries.

Light crude oil

Liquid petroleum that has a low density and flows freely at room temperature.


Calcium carbonate-rich sedimentary rocks in which oil or gas reservoirs are often found.

Liquefied Natural Gas (LNG)

Gas, mainly methane, liquefied under pressure and low temperature.

Liquefied Petroleum Gas (LPG)

Pressure or refrigeration liquefies lighter hydrocarbons, such as propane, butane, pentane, and mixtures of these gases.

LNG Carrier

Tanker, with insulated pressure tanks, designed to carry refrigerated LNG shipments.

Lost Time Injury

Any work related injury or illness which prevents that person from doing any work day after accident

Lost Time Injury Frequency (LTIF)

Number of LTIs recorded for a group of workers, per million hours worked by that group.

Marginal Field

A field that may not produce enough net income to make it worth developing at a given time; should technical or economic conditions change, such a field may become commercial.

Marine Riser

Pipe connecting offshore installation to a subsea wellhead or pipeline for drilling or production purposes.

Mboe / MToe

Million bbls of oil equivalent /

Million tonnes of oil equivalent

Medium crude oil

Liquid petroleum with a density between that of light and heavy crude oil.


The principal constituent of natural gas; the simplest hydrocarbon molecule, containing one carbon atom and four hydrogen atoms.

Middle distillates

Medium-density refined petroleum products, including kerosene, stove oil, jet fuel and light fuel oil.


The processing, storage and transportation sector of the petroleum industry.


Self-contained box or package built with a specific purpose (for example, well head, oil and gas separation, gas compression, platform power generation, mud, storage, diesel, filter and exhaust) located on production installations.

Natural Gas

Gas, occurring naturally, often found in association with oil.

Natural gas liquids (NGL)

Liquids obtained during natural gas production, including ethane, propane, butanes and condensate.

Near miss / accident

Any event which had potential to cause injury and/or damage and or/loss, but which was avoided by circumstances.

Oil Equivalent

Method of assessing work of calorific value of different sources of energy in terms of one tonne of oil.

Oil sands

A deposit of sand saturated with bitumen.

Oil terminal

Term designating facilities used for storing oil and natural gas produced, as well as all infrastructures needed for oil and gas tanker loading and unloading operations.


Company which operates a Licence, either on its own behalf, or, if a member of a consortium, on behalf of Licensees. Takes primary responsibility for day-to-day operations for an activity (exploration, development or production).

Particulate matter

Refers to microscopic solid or liquid particles that remain suspended in the air for some time.


The capacity of a reservoir rock to transmit fluids; how easily fluids can pass through rock.


Cracks and pore spaces between the rock particles (such as porous sandstone or fractured limestone) are interconnected and are large enough to permit fluid movement.

Personal Protection Equipment (PPE)

Equipment / clothing which offers protection against risks to health and safety.


A naturally occurring mixture composed predominantly of hydrocarbons in the gaseous, liquid or solid phase.

Petroleum Products

Gasoline, kerosene, heavy fuel oil, lubricating oils, petroleum jelly, and paraffin consist principally of mixtures of paraffin hydrocarbons, which range from lighter liquid members to solid members.


Device for cleaning a pipeline or separating two liquids being moved down pipeline. (Intelligent pig - fitted with sensors to check for corrosion or defects in pipelines.)


Long steel piles driven into the seabed to anchor fixed offshore structures solidly in place.


A pipe through which natural gas, crude oil or petroleum products are pumped between two points, either onshore or offshore.


Level of peak oil or gas field production; it is always followed by declining level of production.


Fixed structure resting on seabed or piled into it.


Process whereby a well that is no longer needed is filled with concrete and abandoned


A natural underground reservoir containing an accumulation of petroleum.


The volume of spaces within rock that might contain oil and gas (like the amount of water a sponge can hold); the open or void space within rock ?usually expressed as a percentage of the total rock volume. Thus porosity measures the capacity of the rock to hold natural gas, crude oil or water.

Primary recovery

The production of oil and gas from reservoirs using the natural energy available in the reservoirs and pumping techniques.

Probable Reserves

Reserves not yet "proven", but are estimated to have a better than 50% chance of being technically and economically producible.

Production Drilling

Drilling of wells in order to bring a field into production.

Production Installation

An installation from which development wells are drilled and that carries all associated processing plants and other equipment needed to maintain a field in production.

Production sharing (contract)

Contract by which the production of a field is shared between the host government and the oil company operating the field. The company is paid in the form of "cost oil", to cover the exploration and development expenses borne by it alone, and "profit oil", which represents its profit on the venture.

Proven Reserves

Reserves which on available evidence are virtually certain to be technically and economically producible.


Plant where crude oil is separated and transformed into marketable products.

Reformulated fuels

Gasoline, diesel or other fuels which have been modified to reflect environmental concerns, performance standards, government regulations, customer preferences or new technologies.


Subsurface, porous, permeable rock formation in which hydrocarbons are present.

Reservoir Engineering Model

Used to predict reservoir behaviour during production to enable selection of most efficient method of recovery.


Measure of likelihood of occurrence of an undesirable event and of potentially adverse consequences.

Risk Assessment

Careful consideration by competent persons of hazards associated with a task. Potential effect of each hazard, how serve it might be and likelihood of it occurring, should be considered to determine effort required to make site as safe as reasonably practicable.

Risk Management

System that eliminates or mitigates threat from hazards.


The owner's share of production or revenues retained by government or freehold mineral rights holders. In natural gas operations, the royalty is usually based on a percentage of the total production.


A compacted sedimentary rock composed mainly of quartz or feldspar; a common rock in which oil, natural gas and/or water accumulate.

Secondary recovery

The extraction of additional crude oil, natural gas and related substances from reservoirs through pressure maintenance techniques such as waterflooding and gas injection.

Sedimentary basin

Terrain consisting of superposed layers of rock formed from the deposition of sediment over vast tracts of ocean or lake beds, over the course of geological eras.

Sedimentary Rock

Formed by consolidation of deposits formed by settlement of sand, silt, and

other materials.

Seismic (analysis)

The seismic principle is to generate elastic waves methodically and study their propagation through the subsoil. The seismic waves are refracted and reflected as they travel through the various rock strata, and are detected at the ground or sea surface by appropriately placed geophones. The seismic records are interpreted to generate information concerning the shape of the underground strata in the explored region.

Seismic Surveys

Measurements of seismic-wave travel. Seismic exploration is divided into refraction and reflection surveys, depending on whether the predominant portion of the seismic waves' travel is horizontal or vertical. Refraction seismic surveys are used in exploration. Seismic reflection surveys detect boundaries between different kinds of rocks; this detection assists in mapping of geologic structures. 

Semi-submersible Rig

Mobile drilling platform with floats or pontoons submerged to give stability while operating. Used in deeper waters down to 360 metres or more. Kept in position by anchors or dynamic positioning.

Slug Catcher

Plant installed in a gas pipeline system to catch unwanted "slugs" of liquid.

Solution gas

Natural gas that is found with crude oil in underground reservoirs. When the oil comes to the surface, the gas expands and comes out of the solution.

Sounding well

Hole for obtaining data concerning the characteristics of a field.

Sour gas

Natural gas containing significant quantities of hydrogen sulfide.

Source Rock

Rocks containing sufficient organic substances to generate hydrocarbons.

Spot Market

International market in which oil or oil products are traded for immediate delivery at current (spot) price.


Commencement of drilling operations.


Industry activities often affect surrounding areas and populations. People with an interest in these activities are considered stakeholders. They may include nearby landowners, municipalities, Aboriginal communities, recreational land users, other industries, environmental groups, governments and regulators.

Steam injection

An improved recovery technique in which steam is injected into a reservoir to reduce the viscosity of the crude oil.

Steam-assisted gravity drainage (SAGD)

A recovery technique for extraction of heavy oil or bitumen that involves drilling a pair of horizontal wells one above the other; one well is used for steam injection and the other for production.

Stratigraphic Traps

Originate where suitable combination of rock types is deposited in a particular environment.


A separation process that consists in injecting water steam into the distillation residue in order to recover the lightest molecules.

Structural Traps

Formed by Earth movements that fold rocks into suitable shapes or juxtapose reservoir and sealing rocks along faults. Traps may also form when rocks are domed over rising salt masses


Refers to rock formations lying beneath long, horizontal layers of salt. These rock formations may contain hydrocarbons

Subsea Manifolds


Allows wells to be put on production without need to build a platform to operate and maintain wells.


Subsea Wellhead

A wellhead installed on the sea floor and controlled remotely from a platform, a floating production facility or land.

Sustainable Development

To meet the needs of the present without compromising the ability of future generations to meet their own needs. (The World Commission on Environment and Development, Our Common Future, Oxford University Press, 1987)

Sweet oil and gas

Petroleum containing little or no hydrogen sulphide.

Synthetic crude oil

A mixture of hydrocarbons, similar to crude oil, derived by upgrading bitumen from oil sands.

Synthetic Natural Gas (SNG)

Gases made from coals and other hydrocarbon-containing substances.

Tar sands

Another name for oil sands. A deposit of sand saturated with bitumen.

Tertiary recovery

The third major phase of crude oil recovery that involves using more sophisticated techniques, such as steam flooding or injection of chemicals, to increase recovery.

Three-dimensional Seismic / 3-D Seismic

Three-dimensional images created by bouncing sound waves off underground rock formations; used to determine best places to drill for hydrocarbons.

Tight gas

Gas with very low flow rates. Found in sedimentary layers of rock that are cemented together so tightly that it "greatly hinders" the extraction. Getting tight gas out usually requires enhanced technology like "hydraulic fracturing" where fluid is pumped into the ground to make it more permeable.

Ultimate potential

An estimate of recoverable reserves that will have been produced by the time all exploration and development activity is completed; includes production-to-date, remaining reserves, development of existing pools and new discoveries.

Undiscovered recoverable resources

Those resources estimated to be recoverable from accumulations believed to exist based on geological and geophysical evidence but not yet verified by drilling, testing or production.


The process of converting heavy oil or bitumen into synthetic crude oil.


The companies that explore for, develop and produce Indonesia's petroleum resources are known as the upstream sector of the petroleum industry.


The resistance to flow, or "stickiness" of a fluid.

Water Injection

Water is pumped into alternate wells in a field. Pressure in reservoir as a whole can be maintained or increased and production can be maintained or increased.


A hole drilled or bored into the earth, usually cased with metal pipe, for the production of gas or oil.

Wet Gas

Natural gas having significant amounts of heavier hydrocarbons in gasoline range.


A well drilled in an area where no oil or gas production exists.


Abbreviation for barrel. 1 barrel = 159L = 5.9GJ


Billion Cubic Feet (One bcf = 0.176 Mboe)

bopd / boe

bbls of oil per day / bbls of oil equivalent.


Cubic feet per day

m / mcf

Thousands / Thousands of Cubic Feet (of Gas)


"m" in oil and gas stands for 1,000. mm = 1,000,000. so mbbl = 1,000 barrel, mmcfd = 1,000,000 cubic feet per day

mmbbls / mmboe

Million bbls / Million bbls of oil equivalent


1,000,000 cubic feet of gas = 1.057GJ, 1.1TJ, 0.0011PJ

mmscf / mmscfd

Millions of Standard Cubic Feet (of Gas) /

Millions of Standard Cubic Feet per Day (of Gas)


Trillion (a million million) Cubic Feet (of Gas)