Glossary Q-Z

The transfer of heat through matter or space by means of electromagnetic waves.

The spontaneous emission of radiation from the nucleus of an atom. Radionuclides lose particles and energy through this process.

The classification of coal by degree of hardness, moisture and heat content. “Anthracite” is hard coal, almost pure carbon, used mainly for heating. “Bituminous” is soft coal. It is used to generate electricity and to make coke for the steel industry. “Sub bituminous” is a coal with a heating value between bituminous and lignite. It has low fixed carbon and high percentages of volatile matter and moisture. “Lignite” is the softest coal and has the highest moisture content. It is used for generating electricity and for conversion into synthetic gas. In terms of Btu or “heating” content, anthracite has the highest value, followed by bituminous, sub bituminous and lignite.

To enlarge a wellbore. One of the most common reasons for reaming a section of a hole is that the hole was not drilled as large as it should have been at the outset. This can occur when a bit has been worn down from its original size, but might not be discovered until the bit is tripped out of the hole and some undergauge hole has been drilled. Also, some plastic formations may slowly flow into the wellbore over time, requiring the reaming operation to maintain the original hole size.

The percentage of oil or gas in place in a reservoir that ultimately can be withdrawn by primary and/or secondary techniques.

An installation that manufactures finished petroleum products from crude oil, unfinished oils, natural gas liquids, other hydrocarbons, and oxygenates.

The process of warming LNG until it returns to its gaseous state.

Facility for receiving, unloading, storing and re-gasifying LNG.

Energy resources that are naturally replenishing but flow-limited. They are virtually inexhaustible in duration but limited in the amount of energy that is available per unit of time. Renewable energy resources include: biomass, hydro, geothermal, solar, wind, ocean thermal, wave action, and tidal action.

The economically mineable part of Measured or Indicated Coal Resource at the time of reporting as defined in the JORC Code.

Short term capacity reserve and medium term capacity reserve as required in accordance with the power system security and reliability standards.

Volumes of hydrocarbons that are considered to be economically recoverable using current technology.

Reserves change during the year, before the deduction of production, divided by production during the year. An annual RRR of 100% indicates full replacement of production by reserve additions for that year.

The reserve requirement is the amount needed to satisfy the standards in the System Reliability Panel determination of 4 June 1998 and subsequently. The NEM Reliability Standard requires that the level of Unserved Energy (USE) in any region of the NEM must not, on average, exceed 0.002% of the total energy consumed in that region in a year. USE could arise through any combination of insufficient:
    -    Generation capability;
    -    Demand side response; and
    -    Transmission capacity to supply major
         load centres.

A porous and permeable underground formation containing an individual and separate natural accumulation of producible hydrocarbons (crude oil and/or natural gas) which is confined by impermeable rock or water barriers and is characterised by a single natural pressure system.

A computerised model used to simulate a defined reservoir to analyse factors such as flow of oil, gas, and water for a defined drilling program.

Private households which consume energy primarily for space heating, water heating, air conditioning, lighting, refrigeration, cooking and clothes drying.

The part of the coal deposit for which there is a reasonable prospect for eventual economic extraction as defined in the JORC Code.

All end consumers, including both mass market and commercial and industrial (C&I) customers.

To fit into or onto equipment already in existence or service.

A process by which liquid hydrocarbons are formed in a gas reservoir as a result of pressure in the reservoir falling below dew point pressure during production.

The sidewalls of an underground roadway. “Rib spall” refers to the periodic slabbing of coal from the sidewalls.

Areas where the earth is being pulled apart to create faults and areas of subsidence.

A unit of exposure to radiation like X-rays.

State government charges for extraction of petroleum or resources.

Raw coal as mined that has not undergone any screening, crushing or beneficiation.   

A binding agreement for the transfer of an asset between a buyer and a seller.

The shutdown of a generating unit, transmission line, or other facility, for inspection or maintenance, in accordance with an advance schedule.

Any of several forms of chemical/physical devices that remove sulfur compounds formed during coal combustion. These devices, technically know as flue gas desulfurisation systems, combine the sulfur in gaseous emissions with another chemical medium to form inert “sludge,” which must then be removed for disposal.

A barrier created by an impermeable rock, commonly shale, which prevents oil or gas from migrating away from the reservoir.

Enhanced recovery of oil or gas from a reservoir beyond the oil or gas that can be recovered by natural flowing and pumping operations. Secondary recovery techniques involve maintaining or enhancing reservoir pressure by injecting water, gas or other substances into the formation.

Data that is acquired by reflecting sound from underground strata and is processed to yield a picture of the sub-surface geology of an area.

Mobile offshore drilling platform with floats on pontoons submerged to give stability while operating, kept in position by anchors or dynamic positioning.

Any material that has a limited capacity for conducting an electric current. Certain semiconductors, including silicon, gallium arsenide, copper indium diselenide, and cadmium telluride, are uniquely suited to the photovoltaic conversion process.

A mine that reaches the coal bed by means of a vertical shaft.

An Agreement for the transfer of shares in a company between a buyer and a seller.

The strip of coal, usually about 1m thick, that is cut from the longwall block during each cycle of the longwall face.

A form of underground mining that involves the use of a continuous mining machine and movable roof supports to shear coal panels 150 to 200 feet wide and more than half a mile long. Although similar to longwall mining, shortwall mining is generally more flexible because of the smaller working area. Productivity is lower than with longwall mining because the coal is hauled to the mine face by shuttle cars as opposed to conveyors.

The detectable presence of hydrocarbons observed during the drilling of a well: generally further work is required to determine if a show is indicative of a commercial accumulation.

To drill a secondary wellbore away from an original wellbore. A sidetracking operation may be done intentionally or may occur accidentally. Intentional sidetracks might bypass an unusable section of the original wellbore or explore a geologic feature nearby. In the bypass case, the secondary wellbore is usually drilled substantially parallel to the original well, which may be inaccessible due to an irretrievable fish, junk in the hole, or a collapsed wellbore.

Refers to a moving mass of accumulated liquid which can cause damage to gas transmission and distribution infrastructure.

Arrangement of piping designed to catch a slug of liquid in the gas pipeline to separate it from the gas.

A mixture of water and any several finely crushed solids, especially cement, clay or coal.

A smart meter provides a digital reading of electricity usage by time of day. They enable a customer to better manage electricity usage. It also enables electricity companies to offer better pricing to consumers who are able to use less electricity during peak times.

A general term for the visible and near visible (ultraviolet and near-infrared) electromagnetic radiation that is emitted by the sun. It has a spectral, or wavelength, distribution that corresponds to different energy levels; short wavelength radiation has a higher energy than long-wavelength radiation.

The process of concentrating sunlight on a relatively small area to create the high temperatures needed to vaporise water or other fluids to drive a turbine for generation of electric power.

Contaminated with sulphur or sulphur compounds, especially hydrogen sulphide.

A sedimentary rock which is capable to generating hydrocarbons under optimum maturation conditions of temperature, pressure and time.

The use of energy to generate heat for warmth in housing units using space-heating equipment. The equipment could be the main space-heating equipment or secondary space-heating equipment. It does not include the use of energy to operate appliances (such as lights, televisions, and refrigerators) that give off heat as a byproduct.

Spark spread is the relative difference between the price of fuel and the price of power. Spark spread is highly dependent on the efficiency of conversion.

A measure of the density of a material usually obtained by comparing it with water.

Irradiated fuel that is permanently discharged from a reactor. Except for possible reprocessing, this fuel must eventually be removed from its temporary storage location at the reactor site and placed in a permanent repository.

The deepest structural level that hydrocarbons can fill an accumulation before spilling out and being lost to that trap.

Spinning reserve refers to the amount of spare generation capacity available in the system at any one moment.

Natural gas which is available to be purchase on a short term basis and is presented to customers on an as-available basis.

Commence drilling of an oil or gas well.

All energy production and consumption including electricity and direct uses of energy for heating and industrial processes, but excluding transport.

Oil or gas field processes to enlarge old channels, or create new ones, in the producing formation of a well designed to enhance production. Examples include acidising and fracturing.

An analytical process involving randomly selected samples from a probability distribution.

Facilities used to store natural gas.

The study of the strata of the earth including the relative age and composition.

The length of a deposit able to be accessed for mining.

The entire length of casing; tubing or drill pipe used in a drilling operation.

An oil or gas well that produces at relatively low rates. For oil, stripper production is usually defined as production rates of between 5 and 15 barrels of oil per day. Stripper gas production would generally be anything less than 60 thousand cubic feet per day.

A trap that is formed as a result of folding, faulting or a combination of both.

A coal whose properties range from those of lignite to those of bituminous coal and used primarily as fuel for steam-electric power generation. It may be dull, dark brown to black, soft and crumbly, at the lower end of the range, to bright, jet black, hard, and relatively strong, at the upper end. Sub bituminous coal contains 20 to 30 percent inherent moisture by weight.

Facility equipment that switches, changes, or regulates electric voltage.

A system that collects data from various locations on a power system, then send this data to a central computer where it is managed.

Crude oil containing very little sulphur as opposed to Sour Crude Oil which has high sulphur content.

Equipment used to tie together two or more electric circuits through switches. The switches are selectively arranged to permit a circuit to be disconnected or to change the electric connection between the circuits.

A fold in rock in which the strata dip inward from both sides toward the axis. The opposite of anticline.

The minimum payment level guaranteed by a buyer, regardless of actual receipt of product. Buyer pays seller for the value of gas which it is unable to receive below the Take or Pay minimum quantity.

An oil price marker for light sweet crudes in the Asian region.

A mining lease, exploration permit, or mineral development licence.

The third major phase of recovery of oil or gas, the quantities recovered being over and beyond what could be produced by primary and secondary recovery technology; generally involves using sophisticated techniques such as heating the reservoir to reduce the viscosity of the oil.

Commonly shortened to 3-D seismic. Three-dimensional images created by bouncing sound waves off underground rock formations; used by oil companies to determine the best places to drill for hydrocarbons.

An electric system or load consisting of three conductors energised by alternating voltages that are out of phase by one third of a cycle. This type of system has advantages over single-phase including the ability to deliver greater power using the same ampacity conductors and the fact that it provides a constant power throughout each cycle rather than a pulsating power, as in single-phase. Large power installations are generally three-phase.

A drilling apparatus, which has the ability to turn within an extremely tight (30cm) radius, is lowered into the well to the depth of a coal seam, rotating and propelling itself forward as it cuts through the coal. The holes that are drilled increase the effective permeability of the coal seam and allow the methane to find a pathway to the surface.

Metric tonne = 1,000 kilograms.

A stationary device that increases or decreases the voltage in an electricity system.

Activities pertaining to a transmission network including the conveyance of gas or electricity.

The provision of access to the transmission network to transfer energy for trade within the market. Customers may incur a TUOS charge for the export or import power

A formation in the earth’s sub-surface which prevents the onward migration of hydrocarbons.

Usually a continuous steel pipe that is run from the wellhead to the reservoir to transport hydrocarbons from the reservoir to the surface. Usually part of the Completion.

A machine for generating rotary mechanical power from the energy of a stream of fluid. Turbines convert the kinetic energy to mechanical energy.

A type of contract where contractor carries out and completes in assignment for a fixed fee; opposite of a reimbursable contract.

The extent to which the pressure that a formation is exposed to in a well bore is below the internal fluid pressure of the formation.

Upstream oil and gas refers to the operational stages in the oil and gas industry between exploration and refinement. The term covers extraction from reservoir through to sales point of separated, stabilised product, including gas processing and LNG production but excluding refining.

The Maximum Market Price for electricity traded in the NEM. In February  2009 the AEMC announced a draft rule to increase the level of the VoLL from $10,000/MWh to $12,500 per MWh, with effect from 1 July 2010.

The pipeline from Barnawartha to Wagga Wagga, connecting the Victorian and NSW transmission systems. The point of connection is at Culcairn. It is necessary to distinguish thus from VicHub (Longford) and the SEA Gas (Iona) interconnections.

The Victorian Wholesale Gas Market determines a market price used by all Participants to trade gas imbalances which exist between the gas supplied by a Participant and that consumed by the Participant and their customers.

A measure of fluids resistance to flow.

The measurement of the maturity of organic matter within a rock, usually to determine whether it has produced hydrocarbons or is likely to be an effective source rock.

The volt is the international measure of electrical potential or electromotive force. A potential of one volt appears across a resistance of one ohm when a current of one ampere flows through that resistance. The higher the electric potential, or volt, the greater the amount of electrical energy that can be transferred through a circuit.

A recovery method whereby water is injected into a reservoir to displace oil to enhance production.

The fraction of water in given pore space.

A watt (W) is a measure of electricity.
1 watt = 1 volt x 1 amp = 1 joule/second.
A kilowatt (KW) is one thousand watts.
A megawatt (MW) is one million watts.
A gigawatt (GW) is one billion watts.

A hole bored or drilled into the Earth for the purpose of obtaining water, oil or gas, or other natural resources.

The well production or injection rate.

The component that is used to suspend casing strings and provide sealing functionality for oil and gas wells. Wellheads can be located on oil platforms, subsea or onshore.

A popular type of crude oil that is produced in the United States. The New York Mercantile Exchange trades a contract based on West Texas Intermediate (WTI) crude oil delivered in Midland, Texas, which is the U.S. benchmark grade. WTI crude oil is a light, sweet crude oil. Prices for WTI are quoted at Cushing, Oklahoma, which is a major crude oil shipment point that has extensive pipeline connections to oil producing areas and Southwest and Gulf Coast-based refining centres.

A mixture of hydrocarbons that contain a significant amount of liquid or condensable compounds heavier than ethane. These compounds may include propane or butane.

The mechanism through which participants can trade in the Western Australia electricity market (SWIS). Trading on the WEM commenced in September 2006.

Speculative exploration well drilled in search of a new oil or gas accumulation.

Kinetic energy present in wind motion that can be converted to mechanical energy for driving pumps, mills, and electric power generators.

Wire or cable used for down hole operations. Usually either steel wire used to lower instruments into a well or electric for recording instruments.

A comparative measure of thermal energy flow through a given size of orifice. Gases which have the same Wobbe index can replace each other without a change in the relative air-fuel ratio at the same fuel metering settings.

A company’s equity interest in a joint venture or acreage before reduction for royalties or production share owed to others under the applicable fiscal terms.

Re-entry into a completed well for modification or repair work.

A kind of uranium concentrate obtained from leach solutions, in an intermediate step in the processing of uranium ores.

An interval of a geological formation that contains one or more oil or gas reservoirs; a portion of a geological formation that has the porosity and permeability to form petroleum traps for oil and natural gas.