Abandonment / Decommissioning	:Process of dismantling wellhead, production and transportation facilities and restoration of depleted producing areas in accordance with licence requirements and /or legislation.
Accident	:Any event which results in injury, and / or damage, and / or loss.
Acid stimulation	:Form of hydrochloric acid is pumped down well hole to enlarge pore space in oil bearing rocks to increase flow and recovery.
Acoustic log	:Record of time taken by a sound wave to travel over a certain distance through geological formations.
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.
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 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.
Alkylation	:Refining process for converting light, gaseous olefins into high-octane gasoline components (reverse of cracking).
Annex B	:Development plan approval to develop and produce from a commercial field.
API gravity	:Scale used to express specific gravity of oils. Higher API gravity, lighter oil.
Appraisal drilling	:Drilling to determine physical extent, reserves and likely production rate of a reservoir, together with properties of oil or gas.
Appraisal well	:A well drilled as part of an appraisal drilling programme.
Aromatics	:Class of hydrocarbons that have at least one benzene ring as part of their structure. Generally describes benzene and benzene derivatives.
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.
Atmospheric pressure	:Weight of atmosphere on surface of Earth. At sea level approx. 1.013 bars.
Bar	:One bar = 100 kPa
Barge	: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.
Barrel (bbl)	:7.3 bbls = One tonne : 6.29 bbls = One cubic metre : One bbl = 159 litres approx.
bcf	:Billion Cubic Feet (One bcf = 0.176 Mboe)
bcm	:Billion Cubic Metres (One bcm = 0.83 MToe)
Benzene	:An aromatic hydrocarbon present to a minor degree in most crude oils. (Products manufactured from benzene include styrene, phenol, nylon and synthetic detergents.)
Billion	:One thousand million (109)
Block	:UKCS acreage one thirtieth of a quadrant (approx. 200 - 250 sq. kms). Generally defined in terms of latitude and longitude, at one-degree intervals.
Blow-down	:Condensate and gas produced simultaneously from outset of production.
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).
BNOC	:British National Oil Corporation set up 1976 abolished 1985.
bopd / boe	:bbls of oil per day / bbls of oil equivalent.
Bottom-hole assembly	:Components, together as a group, that make up lower end of drill-string (drill bit, drill collars, drill pipe and ancillary equipment).
Brent blend	:International marker for crude oil pricing based on a blend of North Sea crudes.
BRIGHT EYE	:Regular UKCS exercise to test search and rescue capability.
British Thermal Unit (BTU)	:One BTU or Btu = 1.05506 kJ = 0.293 watt-hour
Butane (C4H10)	:Either of two saturated hydrocarbons, or alkanes, with chemical formula. In both compounds carbon atoms are joined in an open chain.
Calorific equivalents	:One cubic foot of gas = 1000 BTUs = 1055.06 kJ Approx. one million tonnes of oil = 40 x 1012 BTUs = 40,400 MJ
Candela	:SI unit of light intensity defined as 1/60 of the light radiated from a sq. cm of a blackbody, a perfect radiator that absorbs no light, held at the temperature of freezing platinum.
Capping	:Tightly closing a well so that hydrocarbons cannot escape.
Carbon	:Atomic number is 6; element is in group 14 (or IVa) of periodic table. Carbon content of a hydrocarbon determines, to a degree, hydrocarbon's burning characteristics and qualities.
Carbon Dioxide (CO2)	:Colourless, odourless, and slightly acid-tasting gas, sometimes-called carbonic acid gas, molecule of which consists of one atom of carbon joined to two atoms of oxygen. Carbon dioxide in atmosphere tends to prevent escape of outgoing long-wave radiation from Earth to outer space; as more heat is produced and less escapes, temperature of Earth increases. Most important man-made greenhouse gas in UK accounting for 81% of direct global warming potential from national greenhouse emissions in 1990.
Carbon Monoxide (CO)	:Chemical compound of carbon and oxygen.
Cardigan Bay	:Semicircular inlet of Saint George's Channel in Irish Sea, western Wales. Bay is about 105 km long and about 56 km wide.
Casing	:Steel lining used to exclude unwanted fluids; control well pressures; support sides of well bore. Casing Seat - lowest point at which casing is set. Casing head - top of casing set in well; part of casing that protrudes above surface and to which control valves and flow pipes are attached.
Casing perforation	:Holes made in liner of a finished well to allow hydrocarbons to flow into production tube.
Cathodic protection	:Method used to minimise rate of electrochemical corrosion of structures, for example, installations offshore, pipelines and storage tanks.
Cement	: Pumped into space between casing and well bore wall in order to hold casing in place.
Central North Sea (CNS)	:Oil and gas-condensate bearing province (Latitudes 55 degrees - 59 degrees).
Chlorofluorocarbon (CFC)	:Synthetic chemical that is odourless, non-toxic, non-flammable, and chemically inert. Released into atmosphere, chlorine-containing chemicals rise and are broken down by sunlight, whereupon chlorine reacts with and destroys ozone molecules.
Choke	:Device to restrict rate of flow during testing of an exploratory discovery.
Christmas tree	:Branching series of pipes, gauges and valves on top end of each production well to control flow of oil or gas.
Circulation	:Techniques for bringing cuttings from bottom of well bore to surface by continuously pumping drilling mud down through drill-string and up annulus during rotary drilling.
Closed-in	:Descriptive of a well that is capable of producing, but is not currently producing.
Coal	: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.
Coiled tubing	:Used to carry production tubing to bottom of well.
Coiled tubing	:Used to carry production equipment to bottom of well.
Commingling	:Producing oil and gas from two or more reservoirs at different depths, or where product of two or more fields is transported via a common pipeline.
Compensator	:Keeps drill-sting stationary while semi-submersible and derrick move.
Competence	:Ability to perform particular job in compliance with performance standards.
Condensate	:Liquid mixture of pentane and higher hydrocarbons.
Conductor	:Wide-diameter pipe from drilling platform to sea-bed to guide drilling and contain drilling fluid.
Consortium	:A group of unrelated companies acting together in a specific venture (Licence application).
Continental Shelf	:Edge of a continent which lies under seas less than 200 metres deep.
Continental Shelf Act	:Passed by UK Parliament in 1964
Continental Shelf Act	i
Continental Shelf Convention	:Ratified by 22 States and became International Law in 1964
Crane Barge	:Vessel capable of lifting heavy equipment onto / off offshore installations.
Cubic foot	:Standard unit used to measure quantity of gas at atmospheric pressure (One cubic foot = 0.0283 cubic metres).
Cubic metre	:SI unit used to measure quantity of gas at atmospheric pressure (One cubic metre = 35.31 cubic feet).
Danger	:Risk of injury
Dangerous occurrence	:Readily identifiable event with potential to cause an accident or disease to persons at work and public or of significant actual of potential material damage.
Dead Weight (dwt)	:Difference between loaded and unloaded weights of a ship.
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.
Derrick	:Elongated pyramid of latticed steel mounted over bore hole for suspending and rotating drill pipes.
Development	:Phase on which a proven oil or gas field is brought into production by drilling production (development) wells.
Development well	:A production well drilled with intent of producing oil or gas from a proven field.
Deviated well	:Horizontal well drilled at an angle (over 80 degrees) to vertical.
DG	:Directorate General (department of EU Commission with responsibilities in a certain field, for example, II - Economic and Financial Affairs, III - Industry, XI - Environment, XVII - Energy).
Discovery well	:An exploratory well that finds hydrocarbons.
Down hole	:A term to describe tools, equipment and instruments used in well bore.
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.
Drilling Mud Nomenclature	:Oil Based Mud (OBM), Pseudo Oil Based Mud (POBM), Water Based Mud (WBM).
Drilling Muds / Fluid	: mud for the well perforation
Drill-string	:Series of connected 9 meter length drill pipes (joints).
Dry gas	:Or Lean gas is natural gas composed mainly of methane.
Dry Hole	:Unsuccessful well, drilled without finding commercial quantities of hydrocarbons.
Dual Completion	:A well completed to produce from two separate reservoirs.
Energy Charter Treaty (ECT)	:Signed by 45 governments and EU in Lisbon, Portugal on 17 December 1994.
English Channel (EC)	:Narrow sea separating France and UK. It is 180 km wide in west where it meets Atlantic Ocean and narrows to 34 km at Strait of Dover in east at its junction with the North Sea.
Enhanced reach	:Deviated wells (over 65 degrees) from vertical and reach out horizontally more than twice vertical depth.
Environment	:External surroundings and conditions in which a company or an individual operates or which may effect, including living systems therein.
Environmental controls	:Put in place to meet or exceed legal requirements and to minimise impact on environment.
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.
Esters	:Compounds formed by combination of acids and alcohols.
Ethanol	:Chemical formed by fermentation or synthesis.
Ethene	:Or Ethylene simplest member of class of aliphatic organic compounds called alkenes, which contain at least one carbon-carbon double bond. Ethylene is a colourless, slightly sweet-smelling gas of formula H2C=CH2. It is slightly soluble in water and is produced in commercial amounts by cracking and fractional distillation of petroleum and from natural gas.
EU	:European Union
Exploration	:Search for hydrocarbons by Geological and Geophysical (G&G) surveys that may be followed by exploration drilling.
Exploration well	:Drilling to determine whether hydrocarbons are present.
Exposure	:Measurement of time during which subject is at risk from a hazard.
Farm-in	: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).
Fatal Accident Frequency Rate (FAFR)	:Number of fatalities per 100 million man hours worked.
Fatality	:Death due to work related injury / illness.
Fatality Rate (FR)	:Number of fatalities per 1000 employees.
Field	:Geographical area under which an oil or gas reservoir lies.
Field Nomenclature	Field ceased production (FCP) Field under development (FUD) Field in production (FIP)
Flare Stack	:Steel structure on an offshore installation or at a processing facility from which gas is flared.
Flaring and venting	:Flaring is burning of hydrocarbon gases for commercial or technical reasons. Venting is release of gases to atmosphere.
Flash Point	:Lowest temperature at which vapour above a flammable liquid can be ignited.
Floating Vessel Nomenclature	Floating accommodation for offshore personnel (Flotel). Floating Production, Storage and Offloading Vessel (FPSO) Floating Production Vessel (FPV) Floating Storage Unit (FSU)
Framework Convention on Climate Change	:UK signed Framework convention at Rio in 1992 and, along with other developed countries, agreed to return its emissions of greenhouse gases to 1990 levels by 2000 - a necessary first step.
Gas Act 1995	:Enabled final liberalisation of gas market by creating licensing framework for new entrants into domestic UK market.
Gas Cap	:In field containing both gas and oil, some gas will often collect at top of reservoir in a single deposit.
Gas Detector	:Instrument to detect presence of various gases.
Gas field	:Field containing natural gas, but no oil.
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 Oil Ratio (GOR)	:Volume of gas at atmospheric pressure produced per unit of oil produced.
Gas Oil Ratio (GOR)	: ratio
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/Condensate field	:Reservoir containing both natural gas and oil, with greater proportion of gas. Condensate appears when gas in drawn from well, an