ABC of oil


Abandoned well: A well permanently plugged in the drilling phase for technical reasons.
Appraisal well: An exploration well drilled to determine the extent and size of a petroleum deposit that has already been discovered by a wildcat well.
Area fee: An annual fee which the licensees on the Norwegian shelf pay the Government for each square kilometre of the acreage covered by a production licence. The fee is demanded pursuant to the provisions in §4-9, paragraph 2 of the Petroleum Act.
Associated gas: Natural gas dissolved in oil.
Awards: Companies that are approved as operators or licensees on the Norwegian shelf may apply to be awarded production licences. The awards take place through licensing rounds and annual allocations in predefined areas. The authorities decide which areas of the Norwegian shelf are to be opened for petroleum activity and which companies are to be awarded production licences.
Barrel of oil: An American volumetric measurement = 159 litres.
Block: A geographical unit of division used in the petroleum activities on the continental shelf. The maritime areas within the outermost limit of the continental shelf are divided into blocks measuring 15 minutes of latitude and 20 minutes of longitude, unless adjacent areas of land, borders with the continental shelves of other nations, or other factors decree otherwise.
Blow-out: Sudden, powerful, uncontrolled discharge of gas, oil, drilling mud and water from a well.
Branch drilling: Drilling from an existing well path towards a new well target.
CNG (Compressed Natural Gas): Natural gas under pressure in tanks.
CO2 tax: A tax paid for burning petroleum and emitting natural gas on platforms used in connection with the production or transportation of petroleum (see the CO2 Tax Act).
Cold flaring: Controlled emission of cold gas.
Condensate: A mixture of the heaviest components of natural gas. Condensate is fluid at normal pressure and temperature.
Continental shelf: The sea bed and its substrata in the maritime areas which extend beyond Norwegian territorial waters over the entire natural continuation of the land territory to the outermost extent of the continental margin, but not less than 200 nautical miles from the sea boundaries from which the breadth of the territorial waters is measured, yet not beyond the centre line relative to another nation.
Contingent resources: Recoverable petroleum volumes that have been discovered, but for which no decision has been taken, or permission given, to recover.
Core sample: Sample taken from a rock formation by core drilling or the use of a sidewall core.
Crude oil: Liquid petroleum from the reservoir. Most of the water and dissolved natural gas have been removed.
Discovery: A petroleum deposit, or several petroleum deposits combined, discovered in the same well, and which testing, sampling or logging have shown probably contain mobile petroleum. The definition covers both commercial and technical discoveries. The discovery receives the status of a field, or becomes part of an existing field when a Plan for Development and Operation (PDO) is approved by the authorities (see Field).
Discovery success: Technical discovery success is the relationship between the number of technical discoveries and the number of wildcat wells. Economic or commercial discovery success is the relationship between the number of discoveries that are developed or are clearly profitable today and the number of wildcat wells.
Drilling programme: Description that contains specific information concerning wells and well paths relating to planned drilling and well activities.
Dry gas: Almost pure methane gas, lacking water and with few heavy components.
E-operation: See integrated operation
EOR (Enhanced Oil Recovery): The term used for advanced methods of reducing the residual oil saturation in the reservoir.
Exploration well: A well drilled to prove a possible deposit of petroleum or obtain information to delimit a discovered deposit. The term covers both wildcat and appraisal wells.
Field: One discovery, or a number of concentrated discoveries, which the licensees have decided to develop and for which the authorities have approved, or granted exemption for, a Plan for Development and Operation (PDO).
Fixed facility: A facility or installation permanently located on the field during the lifetime of the field. Production ships are covered by this definition if they are intended to be permanently placed on the field.
Flaring: Controlled burning of gas for safety purposes.
Growth in reserves: Any increase in the reserves on a defined field, whether it concerns improved recovery from the same deposit or results from increasing the reserves by developing new discoveries and linking these to the field.
Hydrocarbons: Chemical compounds with molecular chains composed of carbon (C) and hydrogen (H) atoms. Oil and gas consist of hydrocarbons.
Integrated operation: Integrated operation denotes the kind of operation where use is made of the opportunities which new and improved information technology provide by utilising approximate real-time data to achieve better and quicker decisions.
Kick: Loss of control over a well, resulting in uncontrolled backflow of drilling liquid. It is an indication of a blow-out due to the well taking in gas, oil or water.
Licensed acreage: The acreage awarded in a production licence. Only exploration drilling and production may take place in an area covered by a production licence.
Licensee: A physical or legal person, or several such persons, who, under the terms of the Petroleum Act or earlier jurisdiction, has a licence to search for, recover, transport or utilise petroleum. If a licence is awarded to several such persons together the expression licensee can cover both the licensees combined and the individual participant.
Licensing round: See Awards.
LNG (Liquefied Natural Gas): Mainly methane (CH4) transformed into liquid form by cooling.
LPG (Liquefied Petroleum Gases): Mainly propane (C3H8) and butane (C4H10) transformed into liquid by raising the pressure or cooling.
Moveable facility: A facility or installation not intended to be permanently located on the field during the lifetime of the field; for instance, a drilling platform or a well intervention device (see § 3 of the Directions for the Framework Provisions).
Multibranch well: A well drilled to produce and/or inject from several well paths simultaneously.
Natural gas: Hydrocarbons in gaseous form. Gas sold under the name natural gas mainly consists of methane (CH4), and some ethane and propane, small amounts of other, heavier hydrocarbons and traces of contaminants like CO2 and H2S.
NGL (Natural Gas Liquids): A collective term for the petroleum qualities, ethane, propane, isobutane, normal butane and naphtha. NGL are partially liquid at normal pressure.
nmVOC (non-methane Volatile Organic Compounds): The term for volatile, organic compounds, except methane, that evaporate from, among other things, crude oil.
Oblique drilling: Drilling of an exploration well whose path is not planned to be drilled vertically.
Observation well: Production or test production well used to measure specific well parameters.
Oil: Collective term for crude oil and other liquid petroleum products.
Oil equivalents (o.e.): Used to sum up oil, gas, NGL and condensate resource volumes. This estimate will not be exact, but can be carried out using one property as the basis. Energy, mass, volume or value are possible approaches. The Norwegian Petroleum Directorate uses a volumetric conversion of NGL and oil to liquid and a simplified energy-based conversion factor between gas and liquid. The relevant conversion factors are: 1000 Sm3 gas corresponds to 1 Sm3 o.e. 1 Sm3 oil corresponds to 1 Sm3 o.e. 1 tonne NGL corresponds to 1.9 Sm3 o.e.
Operator: The agent who, on behalf of the licensee, is in charge of the day-to-day management of the petroleum activity.
Originally, recoverable petroleum volumes: The total, saleable volumes of petroleum from the start to the end of production, based on the prevailing estimate of the in-place volumes and the recovery factor.
PDO: Plan for Development and Operation of petroleum deposits.
Petroleum: Collective term for hydrocarbons. The term covers all liquid and gaseous hydrocarbons found in a natural state in the substrate, and also other substances recovered in connection with such hydrocarbons.
Petroleum Act: Act of 29 November 1996 No. 72 concerning Petroleum Activities.
Petroleum activity: All activity linked to subsea petroleum deposits, including investigation, exploratory drilling, recovery, transport, utilisation and termination, and also the planning of such activities, but not the transportation of petroleum in bulk by ship.
Petroleum deposit: An accumulation of petroleum in a geological unit, delimited by rock types at structural or stratigraphical boundaries, contact surfaces between petroleum and water in the formation, or a combination of these, such that the petroleum concerned is everywhere in pressure communication through liquid or gas.
Petroleum register: A register of all production licences and licences for the construction and operation of installations for transportation and utilisation of petroleum (see § 6-1 of the Petroleum Act).
PIO: Plan for Installation and Operation.
Play: A geographically and stratigraphically delimited area where a specific set of geological factors is present so that petroleum should be able to be proven in producible volumes. Such geological factors are a reservoir rock, trap, mature source rock, migration routes, and that the trap was formed before the migration of petroleum ceased. All discoveries and prospects in the same play are characterised by the play's specific set of geological factors.
Probability of discovery: Describes the feasibility of proving petroleum in a prospect by drilling. The probability of discovery results from multiplying the probabilities of the existence of the play, the presence of a reservoir, a trap, the migration of petroleum into the field and the preservation of petroleum in the field (see Play).
Production licence: This licence gives a monopoly to perform investigations, exploration drilling and recovery of petroleum deposits within the geographical area stated in the licence. The licensees become owners of the petroleum that is produced. A production licence may cover one or more blocks or parts of blocks and regulates the rights and obligations of the participant companies with respect to the Government. The document supplements the provisions of the Petroleum Act and states detailed terms for the individual licences. Exploration period: At the outset, the production licence is awarded for an initial period (exploration period) that may last up to 10 years. In this period, the licensees are obliged to carry out specific tasks, such as seismic surveying and/or exploration drilling. If these mandatory tasks are fulfilled within the exploration period, the licensees may, in principle, demand to retain up to half the area covered by the award for up to 30 years.
Production well: Collective term for wells used to recover petroleum, including injection wells, observation wells and possible combinations of these.
Prospect: A possible petroleum trap with a mappable, delimited volume of rock.
Recovery: The production of petroleum, including the drilling of production wells, injection, assisted recovery, treatment and storage of petroleum for transport, and loading of petroleum for transportation by ship, as well as the construction, location, operation and use of installations used for recovery.
Recovery factor: The relationship between the volume of petroleum that can be recovered from a deposit and the volume of petroleum originally in place in the deposit.
Recovery well: A well used for production or injection.
Refining: The refining of crude oil is really a distillation process. The components with different boiling points are separated in a distillation tower. When heated, the oil is converted to gas, which condenses again at different temperatures to, among others, petrol, paraffin, diesel, heating oils, coke and sulphur.
Reserves: Remaining, recoverable, saleable volumes of petroleum which the licensees have decided to recover and the authorities have given permission to recover.
Rich gas: A mixture of wet and dry gas (methane, ethane, propane, butanes, etc.).
Rig: A derrick, essential machinery and additional equipment used when drilling for oil or gas on land or from a drilling platform at sea.
Riser: A pipe that transports liquid up from the well to the production or drilling platform.
Royalty: A fee payable to the Government, calculated on the basis of the volume and the value of produced petroleum, at the shipping point on the production site. The fee is demanded pursuant to § 4-9, paragraph 1 of the Petroleum Act.
Seismic (geophysical) investigations: Seismic profiles are acquired by transmitting sound waves from a source above or in the substratum. The sound waves travel through the rock layers which reflect them up to sensors on the sea bed or at the surface, or down in a borehole. This enables an image of formations in the substratum to be formed. The seismic mapping of the Norwegian continental shelf started in 1962.
Shallow borehole: A hole drilled to obtain information about the rock characteristics and/or to perform geotechnical investigations before installations are sited, and which is not drilled to prove or delimit a petroleum deposit, or produce or inject petroleum, water or other medium.
Termination plan: Plan to be presented to the authorities by the licensees before a production permit or a permit to install and operate installations for transport and utilisation of petroleum expires or is relinquished, or the use of an installation finally ceases. The plan must include proposals for continued production or shutdown of production and how installations are to be disposed of.
Undiscovered resources: Recoverable volumes of petroleum that it is estimated may be discovered with further exploration.
Well: A hole drilled to find or delimit a petroleum deposit and/or produce petroleum or water for injection purposes, inject gas, water or another medium, or map or monitor well parameters. A well may consist of one or more well paths and may have one or more terminal points.
Well path: Denotes the location of a well from a terminal point to the wellhead. A well path may consist of one or more well tracks.
Well track: The part of a well path that stretches from a drilling out point on an existing well path to a new terminal point for the well.
Wet gas: A mixture of gas mainly in liquid phase.
Wildcat well: An exploration well drilled to find out whether petroleum exists in a prospect.
Zero emissions and discharges: Means that, in principle, no environmentally hazardous substances, or other substances, are to be emitted or discharged if they can result in damage to the environment (detailed definition in White Paper no. 25 (2002-2003)). Special demands for emissions and discharges in the Barents Sea are that, in principle, no emissions or discharges are to take place during normal operations, irrespective of whether they may result in damage to the environment (detailed definition in White Paper no. 38 (2003-2004)).
Common abbreviations
CO carbon monoxide
CO2 carbon dioxide
NOX nitrogen oxides
VOC volatile organic compounds
nmVOC non-methane volatile organic compounds
SO2 sulphur dioxide
Sm3 standard cubic metre
o.e. oil equivalents
t tonne
mill. millions
bill. billions
bbl barrel (of oil)
boe barrels of oil equivalents
Mbbl Million bbl 1)
Mboe: Million boe 1)
Bcf: Billion cubic feet (109)
Tcf: Trillion cubic feet (1012)