feature 02


1P reserves

Proven reserves (1P) are those reserves that, to a high degree of certainty (90% confidence), are recoverable. There is relatively little risk associated with these reserves. Proven developed reserves are reserves that can be recovered from existing wells with existing infrastructure and operating methods. Proven undeveloped reserves require development.

2P reserves

Proven plus Probable reserves (2P) are those reserves that analysis of geological and engineering data suggests are more likely than not to be recoverable. There is at least a 50% probability that reserves recovered will exceed Proven plus Probable reserves.


Three - dimensional

3P reserves

Proven, Probable plus Possible reserves (3P) are those reserves that, to a low degree of certainty (10% confidence), are recoverable. There is relatively high risk associated with these reserves.

An exploration well
An exploration well or 'wildcat' is one that is just drilled primarily for the purpose of determining that oil of gas actually exists in a subsurface rock formation. Before a will is drilled it is at best an educated guess that petroleum exists in a formation. It is only after a well is drilled into the formation that the presence of oil or gas can definitely be confirmed or denied to be present

A development well
A development well is a well that is drilled after an exploration well has confirmed the presence of petroleum in the formation. Usually it takes several development wells to efficiently produce hydrocarbons from a formation



Artificial Lift
The application of power to lift mechanically or otherwise to surface from a producing well

A fold that is convex upward

Australian Petroleum Production and Exploration Association

Gravity of crude oil or other liquid hydrocarbons measured by a system developed by the American Petroleum Institute

API Gravity
Gravity of crude oil or other liquid hydrocarbons as measured by a system developed by the American Petroleum Institute



The standard unit of measurement for all production and sales. One barrel = 159 litres or 35 imperial gallons.

A synclinal structure in the subsurface (concave upwards) of large areal extent

Billion barrels of oil equivalent

Billion cubic feet, a billion defined as 1,000,000,000. On average 1 bcf of sales gas = 1.055 petajoules.

Billion cubic feet of gas

Barrels of oil equivalent

Barrels of oil equivalent per day

Barrels of oil per day

The uncontrolled flow of oil and / or gas from a well


Steel pipe run into a well to line the hole and protect it from caving and invasion from other formation waters

Casing point
The objective depth in a drilling contract, either a specified depth or the depth at which a specific zone is penetrated

To fix the casing firmly in the hole with cement, which is pumped through the drill pipe to the bottom of the casing and up into the space between the hole and casing

Christmas tree
The assemblage of valves and fittings at the top of a well used in the control of production

To cycle drilling fluids down through drill pipe and up between the drill pipe and the wall of the hole to the surface

Steps used in attempting to bring a well into produciton

Hydorcarbons which are gaseous under reservoir conditions but become liquid at the surface

Confirmation well
A second test well drilled to 'prove' that the formation of producing zone encountered by an initial exploratory well extends beyond the limit of the initial drill and spacing unit

Contingent resources
Quantities of hydrocarbons which are estimated to be potentially recoverable from known accumulations, but which are not currently considered to be commercially recoverable.

A cylindrical column of rock cut by using a special diamond bit to sample an underground formation

Crude oil
Oil as it comes from the well

Chips as small fragments of rock as the result of drilling that are brought to the surface by circulationg drilling mud.



Depreciation, depletion and amortisation of building, plant and equipment, exploration and development expenditure.

Deeper Oil
Oil found at a depth of approximately 7,500 to 10,000 feet (See Shallow Oil)

Delineation well
A tapered mast of open steel framework used in drilling to support the drill string and other equipment

A tapered mast of open steel framework used in drilling to support the drill string and other equipment

Development well
Wells designed to produce hydrocarbons from a gas or oil field within a proven productive reservoir defined by exploration or appraisal drilling.

Deviated hole
A well bore which is off the vertical either by design or accident

Discovery well
An exploration test well that encounters a new and previously untapped oil or gas reservoir

Drill collar
A heavy walled component of the drill string placed between the bit and the drilling pipe to maintain vertical penetration of the bit and supply the weight necessary for drilling

Drilling mud
A mixture of clay, water and chemicals pumped downhole through the drill pipe and drill bit

Drill pipe
High strength pipe, usually on 30 foot lengths with threaded connections on each end

Drill stem
The entire drilling assembly from the swivel to the bit; composed of the kelly, drill pipe and drill collars, used to rotate the bit and to carry the mud or circulating fluid to the bit

Drill stem test
A formation test through drill pipe to determine the presence of oil or gas, along with the pressure

Dry hole
A completed well not producing oil or gas in paying quantities



Exploration and Production

Environmental Effect Statement

Environmental Impact Statement

Electric log
Survey of an uncased hole which measures the ressistivity and spontaneous potential of the rock formations penetrated

Engineering, Procurement, Installation and Commissioning

Exploratory well
A well drilled either in search of a new undiscovered pool of oil or gas, or to extend greatly the limits of a known pool



The particular physical and lithologic characteristics of a rock horizon such as sandstone facies, shale facies, etc. As facies change laterally, (i.e., sandstone to shale) a stratigraphic trap may be developed

A break or fracture zone in the rock in which adjacent rocks have moved relative to one another

Front End Engineerign Design

A test well or group of test wells defining the limit of an oil or gas pool

The burning of unwanted gases as a means of disposing of it during completion operations

Fluid injection
The injection down the bore hole of a single test well of a group of test wells of gas, water or other liquid into a reservoir to force adjacent producing wells.

An individual bed or group of beds distinctive in character and persisting over a fairly large area

Application of hydraulic pressure to the reservoir to create or enlarge fractures through which oil and gas may be produced



Gas cap
The portion of an oil reservoir occupied by free gas

Gas cut
Adjective applied to oil or mud which is mixed with some gas on a drill stem test or completion test

Gas injection
A secondary recovery method in which high-pressure gas is injected into the produced oil to lighten it

Gas to oil ratio
The ratio of gas to oil produced, expressed as cubic feet of gas per barrel of oil



Heavy Oil
A type of crude petroleum characterized by high viscosity and a high carbon-to-hydrogen ratio

Henry Hubb
NYMEX published gas prices

A particular rock or marker zone which can be correlated from well to well

HS & E
Health, Safety and Environment

Solid, liquid or gas compounds of the elements hydrogen and carbon.



Injection well
Well used for the injection of gas or water under pressure into a sub-surface zone


A surge in gas or mud pressure at the top of a well while drilling

Thousand tonnes



Light crude oil
Crude oil with a low wax content

Liquefied Natural Gas

The well site or surface location where a well is to be drilled

Liquefied petroleum gas, the name given to propane and butane in their liquid state.




Thousand barrels

Thousand cubic feet of gas at a specified temperature and pressure

Millions of cubic feet of gas


Mean resource potential
The average of the range of recoverable resources.


Million barrels

Million barrels of oil equivalent

Million standard cubic feet per day

Monterey Rights
The Monterey rights are the rights to drill explore and extract hydrocarbon (oil and gas) from oil and gas traps in one of the major source rocks for oil and gas in the San Joaquin Basin California - namely the Monterey formation. 

Mud log
A progressive analysis of the well bore cuttings and mud circulated up from the bottom of the hole

Multiple completion
The completion of a single well in more than one producing horizon



Natural gas
Gas which occurs naturally, consisting mostly of hydrocarbons which at surface conditions are in a gaseous state

New York Mercantile Exchange



Offset well
A well drilled on the next closest location to the original well

Oil-cut mud (OCM)
Term used to describe a mixture of oil and drilling mud

Oil-in-place (OIP)
The amount of crude oil estimated to exist in a reservoir underlying a pool or field area



Pay zone
The rock strata which constitute the oil and gas reservoir

Holes made in the casing, cement and formation through which formation fluids may blow into the well bore

A measure of the ability of a rock to transmit fluids, usually measured in millidarcies (md)

Petroleum Exploration Society of Australia

Petroleum liquids
Crude oil, condensate, or its derivative naphtha, and the liquefied petroleum gases propane and butane.

Petajoules. Joules are the metric measurement unit for energy. A petajoule equals 1,000,000,000,000,000 joules. The equivalent imperial measure to joules is British Thermal Units (BTU). One kilojoule = 0.9478 BTU.

Plug and abandon
To fill a hole with mud and / or cement when abandoning a well

The percentage of void space in a rock

Leases of other rights on a particular geographical area believed to lie on a specific geologic structural or stratigraphic trap believed to contain oil, gas or both

Proved reserves
Those quantities of crude oil, natural gas and natural gas liquids which upon analysis or geologic and engineering data, appear with reasonable certainty to be recoverable in the future from known oil and gas reservoirs under existing economic and operating conditions

Means the petroleum resource rent tax imposed with respect to petroleum products pursuant to the Petroleum Resource Rent Tax Act 1987 (Cth) and the Petroleum Resource Rent Tax Assessment Act 1987 (Cth)

Production Sharing Contract

Pumping well
A well produced by artificial lift by a subsurface pump



Means the volume of economically recoverable oil or gas contained in a geological formation

A porous and permeable rock formation

Resource potential
Resource potential refers to those quantities of petroleum yet to be discovered. It may refer to single opportunities or a group of opportunities.

A measure of the resistance of rock and its contained fluids to the passage of electrical current

Rotary drilling
The common method of well drilling involving the cutting of a hole by rotating a bit at the bottom of a column of drill pipe



A sedimentary rock consisting almost entirely of sand-sized grains of quartz

The percentage of a rock's pore space occupied by a particular fluid, thus there is oil saturation, water saturation and gas saturation

Standard cubic feet

Secondary recovery
Any method of increasing ultimate recovery of oil or condensate by the application of outside energy

Seismic survey
A geophysical survey of an area consisting of recording the time amplitude of shock waves reflected from substructure strata

A cylindrical steel tank used to separate oil from gas

A sedimentary rock composed of very small particles of clay, mud and sand

Shallow Oil
Oil that is found at a depth of approximately 1,800 to 5,500 feet. (See Deeper Oil)

Show of oil
A small amount of oil in a well or rock sample

To stop a well from producing by closing the valves at the wellhead

Shut-in pressure
Pressure measured after a well has been shut for a period

Sour gas
Gas containing acid gases, principally hydrogen sulphide and carbon dioxide

Society of Petroleum Engineers

To start the actual drilling of a well

sq km
Square kilometers

Step-out well
A well in an unproved or semi-proved area in an attempt to extend the productive limits of a field

The technique of getting more production from a formation by the use of acidizing, hydraulic fracturing or other method

To clean out the bore hole of a well with a special tool attached to a wire line and to attempt to start the well producing. The tool is called a RABBIT



Trillion cubic feet

Tight hole
A drilling well in which all information is kept secret by the operator

Terajoules. Joules are the metric measurement unit for energy. A terajoule equals 1,000,000,000,000 joules.

The position at which oil and / or gas is stopped from further migration and movement

A string of pipe, usually 2-2 1/2 " in diameter, run inside casing and through which oil and gas are produced



A method of secondary recovery in which water is injected into an oil reservoir through injection wells to push toward producing wells

Wildcat exploration
Exploration wells testing new play concepts or structures distanced from current fields.

Wildcat well
An exploratory well drilled some distance from known production. This distance from production determines whether the wildcat is low, medium or high risk

West Texas Intermediate



An interval of a subsurface formation having particular rock characteristics