Glossary

acreage: the area covered by petroleum exploration blocks
acre-foot: a layer of porous reservoir one foot in thickness covering an area of one acre
anticline: upward-arching fold of rock strata
Appraisal Drilling: Drilling carried out following the discovery of a new field to determine the physical extent, amount of reserves and likely production rate of the field.
barrel (bbl): a unit of volume in oil production; one barrel equals 42 United States gallons, 35 Imperial gallons, or approximately 159 litres
basal sand: a sand deposited at the base of a sequence
basement: the igneous and metamorphic rocks that exist below the oldest sedimentary cover. In some areas, such as shields, the basement rocks may be exposed at the surface.
basin: a segment of the earth's crust which has downwarped, and in which sediments have accumulated; such areas may contain hydrocarbons
bcf: billion cubic feet, i.e., 1,000 million cubic feet (equivalent to approximately 28.3 million cubic metres) of gas
bed: a layer of sedimentary rock, distinguishable from layers above and below
block: a petroleum tenement, permit, lease or licence
bopd: barrels of oil per day
carbonate: a sediment formed of calcium, magnesium or iron carbonate minerals such as limestone or dolomite
closure (structural): in a subsurface fold, dome, fault block, or other structural trap; the vertical distance between the structure's highest point and its lowest closed structural contour; reservoirs within closure are potential sites or traps for oil or gas accumulations
condensate: hydrocarbons, often found with natural gas, which are themselves gases in the reservoir but which condense out to liquids when the pressure drops during production
continental shelf: that part of the continental margin extending from the coastline to the continental slope at about 200m
control: refers to the amount or concentration of geological or seismic data available for structural mapping
Cretaceous: a geological period (circa 135-65 million years ago)
cross-section: a (vertical) section drawn at right angles to the long axis of a geological feature
crude oil: a mixture of hydrocarbons occurring naturally in underground deposits; the basic feedstock for petroleum refineries
deep water: water depths greater than 200m
degree API gravity (°API): the specific gravity of oil, measured in degrees on the American Petroleum Institute scale, in which a higher API gravity value indicates a lesser actual specific gravity
"Company" or "Key": means Key Petroleum Limited ABN 120 580 618 and, where the context requires, its subsidiaries;
"PSA": means production sharing agreement;
"US$": means the currency of the United States;
delta complex: an overlapping sequence of deltaic sediments representing changes in the position and shape of a river delta over time
deltaic sediment: a deposit of sediment formed at the mouth of a river either in the ocean or a lake, which results in progradation of the shoreline
deposition: laying down of potential rock-forming material, i.e., sediment
diapir: a dome or anticlinal fold in which the overlying rocks have been ruptured by the intrusion of salt or other plastic core material
dip: the angle that rock strata make with a horizontal surface, measured at right angles to the strike
drillstem test (DST): a test carried out in an oil well, using testing tools attached to the drillstem, in order to assess the producing possibilities of one or more formations intersected by the well
EEL: exclusive exploration licence or permit
ESA: exploration study agreement granting the holder exploration rights over an area
evaporite: a sediment resulting from the evaporation of saline water
facies: the aspect, appearance and characteristics of a rock unit (e.g., member or formation), usually reflecting the conditions of deposition; sedimentary units commonly change laterally from one facies to another, such as from sandstone to shale, reflecting changes in depositional environment
farmin, farmout, farminee. farmer: a joint venture in which an incoming (farmin) partner (farminee) earns an interest in a property by funding costs of appraisal, development or exploration, while the (farmout) partner (farmor) owning the property does not contribute
fault: (to form) a break in the subsurface strata; strata on opposite sides of a fault may be displaced vertically and/or laterally relative to their original position
fault trap: hydrocarbon trap which relies on the termination of the reservoir against a seal, due to fault movement
flysch: rapidly deposited sediments derived from erosion of the Alps as they were being uplifted
fold: a bend in rock strata
formation: a (named) succession of sedimentary beds having some common characteristic
four-way dip closure: a anticlinal feature in which closure is formed by the sediments dipping in all directions
FPSO: floating, production, storage and off-take vessel
fracture: a general term for any break in a rock, whether or not it causes displacement, due to mechanical failure by stress; fractures include cracks, joints and faults
generation (of oil or gas): process by which organic matter is transformed into hydrocarbons in a source rock
geophysics: study of the earth by quantitative physical methods
geothermal gradient: the rate at which temperature increases with increasing depth below the Earth's surface; a general average is around 30°C increase per additional km of depth
graben: a downthrown block of sediments bounded by faults
gravity exploration: the precise measurement of the force of gravity at different points over an area to give an indication of thickness of sediments and of structure
group: a (named) succession of formations having some common characteristic
horst: an elongated uplifted block of sediments bounded by faults
hydrocarbon: a class of naturally-occurring organic compounds containing only carbon and hydrogen atoms (in practice, small quantities of sulphur, oxygen and nitrogen and their compounds may also be present); hydrocarbons include natural gas, liquefied petroleum gas, natural gas condensate and crude oil
Jurassic: a geological period (circa 190-135 million years ago)
km: kilometre
sq. km: square kilometre
lead: a potential petroleum trap which has been identified but has not been adequately defined
License: An agreement in which a national government gives an oil company the rights to explore for and produce oil and/or gas in a designated area.
limestone: a sedimentary rock composed predominantly of calcium carbonate
Lower Tertiary (Palaeocene): the older part of the Tertiary, of which the Palaeocene is the oldest, from 55 million years to 65 million years before present
m: metre
maturation: the process involving time, temperature and pressure in which potential petroleum source rocks may generate hydrocarbons and attain maturity
megasequence: a group of sedimentary sequences which are related in nature or geological history
migration: the movement of oil or gas from a source rock to a reservoir
Miocene: a geological epoch in the Tertiary era (circa 65-2 million years ago)
mmbbl: million barrels (of oil)
mmcf: million cubic feet (of gas)
mmcf/d: million cubic feet (of gas) per day
net pay: the cumulative thickness of porous and permeable reservoir beds within an overall hydrocarbon column in a structure
mmcf/d: million cubic feet (of gas) per day
net pay: the cumulative thickness of porous and permeable reservoir beds within an overall hydrocarbon column in a structure
oil window: the levels of maturity at which source rocks are within the range of conditions favourable for oil generation
operator: the member of an exploration joint venture of two or more exploration companies which has been appointed to carry out all operations on behalf of the parties
overthrust: the result of strong compressional tectonic forces which have thrust a body of rock over an adjoining body along a fault plane
P50: reserves and potential reserves estimates are often expressed as a range of values to describe the uncertainty in the estimate. There is a 50 probability that reserves may be greater (or smaller) than the P50 reserve estimate.
permeability: the degree to which fluids such as oil, gas and water can move through the pore spaces of a reservoir rock
permit: a petroleum tenement, lease, licence or block
petroleum: general term for all phases of naturally-occurring hydrocarbons
PEP: petroleum exploration permit
Pinchout: where a sandstone reservoir thins to nil between two layers of impervious rocks
play: a geological concept which, if proved correct, could result in the discovery of hydrocarbons
plug & abandon (P&A): the process of terminating operations in a well. Cement plugs are set in the borehole and the rig moves off the location. The borehole is thus left in a safe condition. In some cases, where the Operator considers it possible that the well may be re-entered at a later date, the well may be only temporarily plugged and abandoned.
plunging nose: an anticline, the crest of which dips in one direction without four-way closure
possible reserves: those unproved reserves which analysis of geological and engineering data suggests are less likely to be recoverable than probable reserves. In this context, when probabilistic methods are used, there should be at least a 10 probability that the quantities actually recovered will equal or exceed the sum of estimated proved plus probable plus possible reserves
probable reserves: those unproved reserves which analysis of geological and engineering data suggest are more likely than not to be recoverable. In this context, when probabilistic methods are used, there should be at least a 50 probability that the quantities actually recovered will equal or exceed the sum of estimated proved plus probable reserves
prospect (petroleum): a geological or geophysical anomaly that has been surveyed and defined, usually by seismic data, to the degree that its configuration is fairly well established, and on which further exploration such as drilling can be recommended
proved reserves: those quantities of petroleum which, by analysis of geological and engineering data, can be estimated with reasonable certainty to be commercially recoverable, from a given date forward, from known reservoirs and under current economic conditions, operating methods, and government regulations. Proved reserves can be categorized as developed or undeveloped. If deterministic methods are used, the term reasonable certainty is intended to express a high degree of confidence that the quantities will be recovered. If probabilistic methods are used, there should be at least an 90 probability that the quantities actually recovered will equal or exceed the estimate
PSA: production sharing agreement granting the holder exploration and production rights over an area
PSC: production sharing contract granting the holder exploration and production rights over an area
radar oil seep study: a technique for detecting submarine oil seeps by the use of airborne radar to detect oil slicks on the surface of the sea
reserves: quantities of hydrocarbons estimated to be present within a trap, classified as proven, probable or possible
reservoir: a subsurface volume of rock of sufficient porosity and permeability to permit the accumulation of crude oil and natural gas under adequate trap conditions
salt structures: structures formed by the plastic deformation of underlying beds of salt (salt tectonics) e.g. salt anticlines, salt domes
sandstone: a sedimentary rock which is generally composed essentially of sand-sized quartz grains
satellite: geological studies the use of images obtained from satellites to interpret the surface geology of an area
seal: an impervious layer over a reservoir which prevents escape of fluids
section: a general term used to refer to a sequence of sedimentary rocks, e.g. "sedimentary section", "Mesozoic section", etc
sediment (rock formed from): solid material, whether mineral or organic, which has been moved from its position of origin and redeposited
sedimentary rock, sediments: a rock formed as a result of consolidation of loose sediments, often created by weathering
processes,: such as sandstone & shale, or deposited by chemical processes, such as salt or limestone
seismic survey: a type of geophysical survey where the travel times of artificially created seismic waves are measured as they are reflected in a near-vertical sense back to the surface from subsurface boundaries. This data is typically used to determine the depths to the tops of stratigraphic units and in making subsurface structural contour maps and ultimately in delineating prospective structures
seismic (2D): a seismic survey made up of widely spaced lines of data
seismic (3D): a seismic survey made up of very closely spaced data whereby a "3D" image can be processed
seismic reprocessing: the use of the latest computer processing technology to improve the quality of older seismic data
sequence: a succession of sedimentary rocks laid down in order
shale: fine-grained sedimentary rock characterised by finely-laminated structure
shelf: the shallower, marginal part of a sedimentary basin
source unit, source rock: a rock capable of generating oil and gas under the right conditions of temperature, pressure and time
spud: to start the drilling of a well
stratigraphic trap: a type of petroleum trap which results from variations in the lithology of the reservoir rock, which cause a termination of the reservoir, usually on the up-dip extension
stratigraphy: the succession or superimposition of rock strata
structure: a discrete area of deformed sedimentary rocks, in which the resultant bed configuration is such as to form a potential trap for migrating hydrocarbons
sub-basin: a localised depression within a basin
subsidence: a sinking of a large part of the earth's crust relative to the surrounding parts
submarine fan: a fan shaped body of sediments located seawards of rivers or submarine channels
TCF: trillion cubic feet
tectonics: Processes that move and deform the earth's crust
Tertiary: an interval of geological time from 2 million years to 65 million years before present trap a body of reservoir rock, vertically or laterally-sealed, the attitude of which allows it to retain hydrocarbons which have migrated into it
turbidite sediments: typically deposited in deep water which have flowed off the edge of the continental shelf
unconformity: lack of parallelism between rock strata in sequential contact, caused by a time break in sedimentation
up-dip: at a structurally higher elevation within dipping strata
Upper Cretaceous: the later part of the Cretaceous geological period; an interval of geological time from 65 million years to 97.5 million years before present
vuggy porosity: porosity developed in carbonates where a system of holes have developed by solution
Working Interest or W.I.: the Company's share in a joint venture or production sharing agreement and is used for calculation of the Company's costs and production entitlement (before deduction of any royalties or other government share)royalties or other government share)