# A B C D E F G H I J K L M N O P Q R S T U V W X Y Z



denotes a low estimate scenario of Contingent Resources


denotes a best estimate scenario of Contingent Resources


denotes a high estimate scenario of Contingent Resources

2D seismic

seismic data acquired in a single traverse or series of traverses. 2D seismic data provides single cross sections

3D seismic

seismic data acquired as multiple, closely spaced traverses. 3D seismic data typically provides a more detailed and accurate image of the subsurface than 2D seismic



decommissioning costs


The process of summing reservoir (or project) level estimates of resource quantities to higher levels or combinations such as field, country or company totals. Arithmetic summation may yield different results from probabilistic aggregations of distributions


American Petroleum Institute


the phase of petroleum operations immediately following a successful discovery. Appraisal is carried out to determine size, production rate and the most efficient development of a field

appraisal well

a well drilled as part of an appraisal of a field


above sea level





barrels per day


term commonly used to describe areas over which there is a petroleum or production licence


Barrels of oil equivalent. Converting gas volumes to oil equivalent is customarily done on the basis of the nominal heating content or calorific value of the fuel. Before aggregating, the gas volumes must be converted to the same temperature and pressure. Common industry gas conversion factors usually range between 1 barrel of oil equivalent = 5,600 scf of gas to 6,000 scf of gas


barrels of oil per day


British Thermal Unit


billions of standard cubic feet


barrels of water per day


charge or migration

the movement of hydrocarbons from source rocks into reservoir rocks. Migration can be local or can occur along distances of hundreds of kilometres in large sedimentary basins, and is critical to a viable petroleum system


or more properly structural closure is a term geologists use to define the volume of rock in which oil, or gas, can accumulate. Closure is based on the shape of a geological structure and is usually defined as a specific depth. In some reservoirs oil can accumulate outside of structural closure and such reservoirs are referred to as having their hydrocarbon stratigraphically trapped. Stratigraphic traps accumulate oil in deposits shaped by processes such as rivers, beaches, reefs and fractures.

commercial discovery

discovery of oil and gas which the Company determines to be commercially viable for appraisal and development


liquid hydrocarbons which are sometimes produced with natural gas and liquids derived from natural gas

Contingent Resources

these are resources that are potentially recoverable but not yet considered mature enough for commercial development due to technological or business hurdles. For contingent resources to move into the reserves category, the key conditions, or contingencies, that prevented commercial development must be clarified and removed. As an example, all required internal and external approvals should be in place or determined to be forthcoming, including environmental and governmental approvals. There also must be evidence of firm intention by a company’s management to proceed with development within a reasonable time frame (typically 5 years, though it could be longer)


the final period of the Mesozoic era ranging from approximately 65 to 144 million years ago


decommission or decommissioning

the process or the procedure by which the facilities and the infrastructure related to the production of hydrocarbon from an oil field are demobilised and abandoned

decommissioning charge

cost of charge associated with decommission procedures


any area of water over 250m in depth


the angle at which a rock stratum or structure is inclined from the horizontal


an exploration well which has encountered oil and gas for the first time in a structure

drilling campaign

a period of time in which drilling activities are performed

dry well

a well which does not encounter hydrocarbons in economically producible quantities


drill stem test



the epoch after the Palaeocene and before the Oligocene in the Tertiary period from approximately 55.8 million to 33.9 million years ago


emergency shut down


the phase of operations which covers the search for oil or gas by carrying out detailed geological and geophysical surveys followed up where appropriate by exploratory drilling

exploration drilling

drilling carried out to determine whether oil and gas are present in a particular area or structure

exploration well

a well in an unproven area or prospect, may also be known as a "wildcat well"



sedimentological description of rock


a term used to describe when a company sells a portion of the acreage in a block to another company, usually in return for consideration and for the buying company taking on a portion of the selling company's work commitments


a geographical area under which either a single oil or gas reservoir or multiple oil or gas reservoirs lie, all grouped on or related to the same individual geological structure feature and/or stratigraphic condition


a body of rock identified by lithic characteristics and stratigraphic position which is mappable at the earth's surface or traceable in the subsurface


Floating production storage and offloading



geophysical exploration is concerned with measuring the earth's physical properties to delineate structure, rock type and fluid content – these measurements include electrical, seismic, gravity and magnetics



a compound containing only the elements hydrogen and carbon. May exist as a solid, a liquid or a gas. The term describes any combination of oil, gas and/or condensate



oil and gas processing, transportation and off-take facilities



referring to a geological period of the Mesozoic Era from approximately 199 million to 145 million years ago


internal rate of return



an exclusive right to explore for petroleum, usually granted by a national governing body

licence area

the area covered by a licence







measured depth




million barrels


million barrels of oil equivalent


million stock tank barrels


millions of standard cubic feet per day


Managed pressure drilling


natural gas

gas, predominantly methane, occurring naturally, and often found in association with crude petroleum



that geographical area that lies seaward of the coastline


a mixture of liquid hydrocarbons of different molecular weight

oil field

the mapped distribution of a proven oil-bearing reservoir or reservoirs


the epoch after the Eocene and before the Miocene in the Tertiary period approximately from 34 million to 23 million years ago


that geographic area that lies landward of the coastline


the company that has legal authority to drill wells and undertake production of oil and gas. The operator is often part of a consortium and acts on behalf of this consortium


oil water contact



denotes a scenario which has at least a 10% probability of occurring


denotes a scenario which has at least a 50% probability of occurring


denotes a scenario which has at least a 90% probability of occurring

participating interests

the proportion of exploration and production costs each party will bear and the proportion of production each party will receive, as set out in an operating agreement


A generic name for oil and gas, including crude oil, natural gas liquids, natural gas and their products

petroleum system

Geologic components and processes necessary to generate and store hydrocarbons, including a mature source rock, migration pathway, reservoir rock, trap and seal


a distinct state of matter in a system, e.g. liquid phase or gas phase


a conceptual model for a style of hydrocarbon accumulation


parts per million

Probable Reserves

reserves which, based on the available evidence and taking into account technical and economic factors, have at least a 50 per cent. chance of being produced


an identified trap that may contain hydrocarbons. A potential hydrocarbon accumulation may be described as a lead or prospect depending on the degree of certainty in that accumulation. A prospect is generally mature enough to be considered for drilling

Prospective Resources

are estimated volumes associated with undiscovered accumulations. These represent quantities of petroleum which are estimated, as of a given date, to be potentially recoverable from oil and gas deposits identified on the basis of indirect evidence but which have not yet been drilled. This class represents a higher risk than contingent resources since the risk of discovery is also added. For prospective resources to become classified as contingent resources, hydrocarbons must be discovered, the accumulations must be further evaluated and an estimate of quantities that would be recoverable under appropriate development projects prepared.


the likelihood of an area to contain potential hydrocarbon accumulations, i.e. prospects

Proved Reserves

reserves which, based on the available evidence and taking into account technical and economic factors, have at least a 90 per cent chance of being produced



represent that part of resources which are commercially recoverable and have been justified for development, while contingent and prospective resources are less certain because some significant commercial or technical hurdle must be overcome prior to there being confidence in the eventual production of the volumes.


an underground porous and permeable formation where oil and gas has accumulated


Contingent and Prospective Resources, unless otherwise specified



standard cubic feet measured at 14.7 pounds per square inch and 60° F


standard cubic feet per day


standard cubic feet per stock tank barrel


a relatively impermeable rock, commonly shale, anhydrite or salt, that forms a barrier or cap above and around reservoir rock such that fluids cannot migrate beyond the reservoir. A seal is a critical component of a complete petroleum system

seismic survey

a method by which an image of the earth's subsurface is created through the generation of shockwaves and analysis of their reflection from rock strata


characteristic of organic-rich rocks to contain the precursors to oil and gas, such that the type and quality of expelled hydrocarbon can be assessed

source potential

characteristic of a rock formation to constitute a source of oil and gas

source rock

a rock rich in organic matter which, if given the right conditions, will generate oil or gas. Typical source rocks, usually shales or limestones, contain at least 0.5 per cent total organic carbon (TOC), although a rich source rock might have as much as 10 per cent organic matter. Access to a working source rock is necessary for a complete petroleum system


stock tank barrels measured at 14.7 pounds per square inch and 60° F


stock tank barrels per day



the Tertiary Period is a geological period from approximately 65 million to 2.5 million years ago


a configuration of rocks suitable for containing hydrocarbons and sealed by a relatively impermeable formation through which hydrocarbons will not migrate. Traps are described as structural traps (in deformed strata such as folds and faults) or stratigraphic traps (in areas where rock types change, such as unconformities, pinch outs and reefs). A trap is an essential component of a petroleum system


wireline tool

the term wireline refers to a cabling technology used by operators of oil and gas wells to lower a wireline tool, which is equipment or measurement devices, into a borehole. Wireline tools are used to measure geological and fluid properties of the reservoir and can also be used for engineering activities. The cable on which a wireline tool is attached is used to provide electrical power and to provide a means of transferring recorded data to the surface.