Glossary of terms Environmental Performance Indicators


APIAmerican Petroleum Institute.
Barrel, BblIn the energy industry, a barrel is 42 US gallons measured at 60° Fahrenheit. This is approximately 159 litres.
Base fluidThe continuous phase or suspending medium of a drilling fluid formulation.
CH4Methane, the principal constituent of natural gas. One of the primary greenhouse gases.
CO2Carbon dioxide, a colourless, odourless, and nonflammable gas. CO2 emissions occur from the combustion of fossil fuels. CO2 is a primary greenhouse gas.
Crude oilA mixture of hydrocarbons that exists as a liquid in natural underground reservoirs and remains liquid at atmospheric pressure after passing through surface separating facilities. Crude oil is the raw material that is refined into gasoline, heating oil, jet fuel, propane, petrochemicals, and other products.
CuttingsThe particles generated by drilling into subsurface geologic formations and carried out from the wellbore with the drilling fluid. Examples of drill cuttings include small pieces of rock varying in size and texture from fine silt to gravel.
Drilling fluidThe circulating fluid (also called ‘mud’) used in the rotary drilling of wells to clean and condition the hole and to counterbalance formation pressure. See definitions for ‘water-based drilling fluid’ and ‘non-aqueous drilling fluid’ below.
E&PExploration and Production (of hydrocarbons).
Emission rateEmissions of gases per unit of hydrocarbon production.
Energy intensityEnergy consumed per unit of hydrocarbon production.
ExplorationStudy of geological formations to detect the presence of hydrocarbons.
Flare (as an atmospheric emission source category)Includes emissions generated by burning of gases (or in some cases liquids) in a thermal destruction device, including E&P flaring of associated gas (and in some cases liquids) from oil production or well testing. Typical equipment sources in this category include:
  • Flares
  • Thermal Oxidizers
FlaringThe controlled burning of natural gas produced in association with oil in the course of oil and gas exploration and production operations. It also includes the controlled and safe burning of gas which cannot be used for commercial or technical reasons.
Fresh waterThe definition varies in accordance with local statutes and regulations. Where it is not defined by local regulations, fresh water is defined for reporting purposes as nonbrackish water and may include drinking water, potable water, water used in agriculture, etc. The total dissolved solids (TDS) concentration of this water type is up to 2000 mg/l.
Fuel combustion (as an atmospheric emission source category)Includes emissions generated through the consumption of fuel. Typical fuel-consuming equipment types in E&P operations include:
  • Turbines (e.g., driving compressors, generators and pumps)
  • Internal Combustion Engines
  • Heaters
  • Boilers / Reboilers
  • Mobile sources under company’s operational control (see IPIECA/API/IOGP Petroleum industry guidelines for reporting greenhouse gas emissions)
Fugitive emission, fugitive lossesUnintended emissions released to the air, other than those from stacks or vents from the processing, transmission, and/or transportation of fossil fuels. They are often due to equipment leaks and evaporative processes.
Gaseous emissionGaseous emissions to the atmosphere from flaring and venting, process and turbine combustion. Includes fugitive losses from pumps, valves, flanges, pipes, etc.
Gas-oil ratioThe volume of gas at atmospheric pressure produced per unit volume of oil produced.
Greenhouse gasA gas that contributes to the natural greenhouse effect. The primary six greenhouse gases (GHGs) produced by human activities are: carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons and sulphur hexafluoride. For the purpose of this report GHG considers only CO2 and CH4.
HydrocarbonAn organic chemical compound of hydrogen and carbon (see petroleum).
Hydrocarbon productionQuantity of hydrocarbon gas and/or liquids produced.
IPIECAThe global oil and gas industry association for environmental and social issues.
MudCommon term for drilling fluid.
Nitrogen Oxides (NOX)Nitrogen Oxides represent the sum of nitric oxide (NO) and nitrogen dioxide (NO2) expressed as NO2 equivalent. Nitrous oxide (N2O) is not included as a component of NOX. NOX emissions occur from the combustion of fossil fuels for industry and transport and are a function of the type and quantity of fuel burned and the type of combustion device in which they are burned.
NMVOCNon-methane volatile organic compounds: all hydrocarbons other than methane that can vaporise at normal temperature and pressure.
Non-aqueous drilling fluid (NADF)A drilling fluid in which the continuous phase is a waterimmiscible fluid such as an oleaginous material (e.g., mineral oil, enhanced mineral oil, paraffinic oil, or synthetic material such as olefins and vegetable esters). NADFs serve many purposes under difficult drilling conditions. NADFs are usually reused.
NormalizationTo compare emissions from different regions or sources it is useful to relate them to the size of the activity causing the emission. For example, tonnes of CO2 can be presented by their ratio to tonnes of oil and gas produced. This procedure is called normalization.
OffshoreFor this report ‘offshore’ refers to operations that take place at sea, including inland seas directly connecting to oceans. Operations in bays, in major inland seas, e.g., the Caspian Sea, or in other inland seas directly connected to oceans are counted as offshore.
OnshoreFor this report ‘onshore’ refers to operations that take place within a landmass, including swamps, lakes, rivers and estuaries, but excluding major inland seas.
On-site combustionThe local combustion of fuels by E&P companies to produce energy for their operations.
OperatorTerm used to describe a company appointed by venture stakeholders to take primary responsibility for day-to-day operations for a specific plant or activity.
ProcessingThe separation of oil, gas, and natural gas liquids and the removal of impurities.
Produced water (PW)The water (generally brine) brought up from the hydrocarbon-bearing strata during the extraction of oil and gas, including formation water, injection water, and any chemicals added downhole or during the oil/water separation process. For the purposes of this report produced water discharges from crude oil and natural gas facilities are categorised by the source of production and not the location where they occur, i.e., where production is offshore and discharges are generated from an onshore facility, the discharges are reported as offshore.
ProductionAll production activities including production drilling, process and treatment, flaring and venting, in-field pipeline transport, and terminal operations. (see Hydrocarbon production)
Purchased energyEnergy purchased in the form of electricity or steam.
SO2Sulphur dioxide (SO2) can result from the combustion of H2S and other sulphur containing compounds. In this report ‘SO2‘ refers to the sum of sulphur dioxide and sulphur trioxide (SO2) expressed as SO2 equivalent.
Source of emissionsIn the case of gaseous emissions refers to the process by which the emissions are released. Source categories are Energy, Flare, Vent, Fugitive losses and Unspecified.
SpillAny loss of containment from which the released material reaches the environment (i.e., is not retained within secondary or other confinement), irrespective of the quantity recovered. The volume of a spill represents the gross volume reaching the environment, not a net volume remaining in the environment after response. Spills occurring from support and standby vessels are included but spills of produced water or process waste water are excluded. Includes loss of containment resulting from acts of sabotage (such as theft of oil from pipelines and storage, or vandalism); excludes loss as a result of ‘acts of terrorism’/attacks on infrastructure.
Synthetic-based drilling fluidA drilling fluid that has a synthetic material as its continuous phase with water as the dispersed phase. Synthetic-based drilling fluids are a subset of nonaqueous drilling fluids.
SyntheticsSynthetic material as applied to synthetic-based drilling fluid means material produced by the reaction of specific purified chemical feedstock, as opposed to the traditional base fluids such as diesel and mineral oil which are derived from crude oil solely through physical separation processes.
TonneA metric tonne; equivalent to 1,000 kilograms or 2,205 pounds.
TransportThe transfer of hydrocarbons from the site of production to the point of commercial metering or terminal or offshore loading device.
Upstream industryThose operations within the industry to the point where the produced resource is metered into the transportation system. This includes Exploration and Production.
VentingThe controlled release of unburned gas to the atmosphere.
Water-based drilling fluid (mud)A drilling fluid in which water or a water miscible fluid is the continuous phase and the suspending medium for solids, whether or not oil is present.