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Glossary

    A
  • Abandoned well
    - A well that is permanently shut down because it was a dry hole or because it has ceased to produce crude oil or natural gas.
  • Abandonment
    - Permanently shutting down a drilled well so that it can no longer produce crude oil and/or natural gas and so it can be left indefinitely without further attention and will not damage freshwater supplies, potential petroleum reservoirs or the environment.
  • Acidizing
    - A method of improving porosity and permeability of a reservoir by injecting acid under pressure to dissolve reservoir rock.
  • Air drilling
    - The use of compressed air instead of mud as a drilling fluid to remove the cuttings; air drilling increases penetration rates but offers no control over downhole gas pressure or water in subsurface formations.
  • Allowables
    - The rate of production for a well or group of wells that is set by a regulatory authority (conservation commission).
  • Annulus
    - The space between two concentric lengths of pipe or between pipe and the hole in which it is located.
  • API Gravity
    - A scale developed by the American Petroleum Institute for measuring the density or gravity of crude oil; the higher the number, the lighter the oil.
  • Associated gas
    - Gas that is produced from the same reservoir along with crude oil, either as free gas or in solution.


    B
  • Backstopping
    - A service that provides alternate supplies of natural gas in the event that a consumer's gas is not delivered.
  • Barrel
    - The common unit for measuring petroleum. One barrel contains approximately 159 litres.
  • Benchmark crude
    - A specific crude oil, usually a blended crude with defined properties such as API gravity, sulphur content, etc., used as a reference for pricing other crude oils. Typical benchmark crudes are West Texas Intermediate (WTI), Brent (North Sea), Arab Light and Edmonton Par crude. As the price of the benchmark crude fluctuates, other crude oils from the same geographic area move up and down, depending on their properties relative to the benchmark and on supply and demand. Also known as marker crude.
  • Benzene
    - Flammable, colourless to light yellow volatile aromatic hydrocarbon. A byproduct of cokemaking and other industrial processes, benzene is considered to be a carcinogenic (cancer-causing) substance.
  • Bitumen
    - Solid or semi-solid petroleum that cannot be pumped without being heated or diluted.
  • Blowout
    - An uncontrolled flow of gas, oil or other fluids from a well.
  • Blowout preventer (BOP)
    - Equipment that is installed at the wellhead to control pressures and fluids and to prevent uncontrolled fluid flow from the reservoir during drilling, completion and certain remedial operations to restore production.
  • BOP stack
    - Several blowout preventers used in combination.
  • British thermal unit (BTU)
    - The quantity of heat required to raise the temperature of one pound of water by one degree Fahrenheit at or near 60� Fahrenheit. Equivalent to 1,055.056 Joules.
  • Bundled service
    - A service provided by a pipeline or a local distribution company which includes the natural gas as well as all the necessary services required for a consistent supply (backstopping, load balancing, storage).
  • Burner-tip
    - The point of end-use consumption of a particular fuel, such as natural gas or residual fuel oil.
  • Burner-tip price
    - The price of natural gas (or other fuels) paid by the final consumer.

  • C
  • Cable-tool drilling
    - One of two principal methods of drilling for crude oil and natural gas. Cable-tool drilling is the older method and consists of raising and dropping a heavy drill bit, suspended from the end of a cable, so that it pounds and pulverizes its way through the subsurface structures. Water in the hole keeps the cuttings in suspension for removal at regular intervals by bailing.
  • Cap rock
    - Impermeable rocks such as shale, that overlies the reservoir rock and traps natural gas and crude oil in the reservoir. Also, impermeable rock overlying a geothermal reservoir. Also called sealing rock.
  • Casing
    - A type of pipe that is used to encase smaller diameter production pipe for installation in a well. Casing prevents the wall from caving in and protects against groundwater contamination and uncontrolled hydrocarbon releases.
  • Casing-head gasoline (naphtha)
    - A highly volatile liquid that is separated from natural gas at the wellhead and was once used as unrefined gasoline.
  • Cat cracking (catalytic cracking)
    - A refinery process that uses catalysts in addition to pressure and heat to convert heavier fuel oil into lighter products such as gasoline and diesel fuel. Cracking refers to breaking long, heavy carbon molecules into smaller, lighter molecules.
  • Centrifugal pump
    - A rotating pump, commonly used for large-volume oil and natural gas pipelines, that takes in fluids near the centre and accelerates them as they move to the outlet on the outer rim.
  • Clastic
    - Made up of pieces (clasts) of older rock; rock derived from mechanical process; generally sandstone, siltstone or shale.
  • Cogeneration
    - Technology that simultaneously produces power and thermal energy (heat and steam) from a single fuel source. An example is using steam generated for injection into reservoirs to also generate electricity.
  • Coiled tubing
    - A continuous, jointless hollow steel pipe that is stored on a reel and can be uncoiled or coiled repeatedly as required; coiled tubing is increasingly being used in well completion and servicing instead of conventional tubing, which is made up of joined sections of pipe.
  • Coke
    - A high carbon material resembling fine ground up asphalt material. It is a by-product of fuel coking
  • Common depth point method
    - A method of recording and processing seismic signals so that signals belonging to the same subsurface point are brought together.
  • Completion
    - Preparing a newly drilled well for production; usually involves setting casing � pipe that lines the interior of a well to prevent caving and protect against ground water contamination � and perforating the casing to establish communication with the producing formation
  • Consumption
    - End use of energy and energy sources, such as electrical energy, typically measured in kilowatt-hours; or natural gas, typically measured in thousands of cubic feet or millions of British thermal units, or crude oil and petroleum products, usually measured in litres or barrels.
  • Conventional crude oil
    - Crude oil that flows naturally or that can be pumped without being heated or diluted.
  • Core
    - A cylindrical sample of rock cut by a special bit during the drilling process.
  • Cracking
    - A refining process for increasing the yield of gasoline from crude oil; cracking involves breaking down the larger, heavier and more complex hydrocarbon molecules into simpler and lighter molecules through the use of heat and pressure, and sometimes a catalyst. With heavy oil and oil sands, cracking refers to breaking down large, heavy and complex hydrocarbon molecules into simpler, lighter molecules
  • Critical sour gas wells
    - A sour gas well that has the potential to release unsafe levels of hydrogen sulphide, which might affect nearby residents.
  • Critical zone
    - The zone in a well where sour gas will likely be encountered.
  • Crude oil
    - Naturally occurring liquid petroleum.
  • Cuttings
    - Small chips of rock from the formations through which the drill has bored, brought to the surface by the drilling mud.
  • Cyclic steam stimulation
    - A method of producing heavy oil which involves injecting steam, allowing time for the steam to heat and soften the heavy oil and producing the oil from the same wellbore used to inject the steam.

  • D
  • Darcy
    - A standard unit of measure of permeability. One darcy describes the permeability of a porous medium through which the passage of one cubic centimetre of fluid having one centipoise of viscosity flowing in one second under a pressure differential of one atmosphere where the porous medium has a cross-sectional area of one square centimetre and a length of one centimetre
  • Density
    - The heaviness of crude oil, indicating the proportion of large, carbon-rich molecules, generally measured in kilograms per cubic metre (kg/m3) .
  • Derrick
    - A load-bearing tower-like structure over a natural gas or crude oil well that holds the hoisting and lowering equipment for drilling, testing and reworking wells.
  • Desiccant
    - Any absorbent or adsorbent (liquid or solid) that will remove water or water vapour from a material.
  • Desulphurization
    - The process of removing sulphur and sulphur compounds from gases or liquid hydrocarbon mixes.
  • Development well
    - A well drilled in or adjacent to a proven part of a pool to optimize petroleum production.
  • Diesel
    - A mid-product of fractional distillation, heavier than kerosene or naphtha.
  • Diluent
    - A liquid used to dilute bitumen to the point where it will flow. Condensate is the most commonly used diluent in the oilsands industry
  • Directional (deviated) well
    - A well drilled at an angle from the vertical by using a slanted drilling rig or by deflecting the drill bit; directional wells are used to drill multiple wells from a common drilling pad or to reach a subsurface location beneath land or water where drilling cannot be done.
  • Directional drilling
    - Drilling a wellbore at any angle other than vertical; used where the rig cannot be set up directly over the target, or to drill more than one hole from a single location.
  • Discovery well
    - Exploratory well that discovers a new gas or oil field.
  • Dispute resolution
    - Process to resolve conflicts in mutually beneficial ways, using techniques such as negotiation or third-party mediation instead of public hearings or courts
  • Distillation tower
    - A tall, cylindrical steel tower divided by a number of perforated trays, used in fractional distillation to collect distilled liquids as they condense.
  • Downstream
    - The refining and marketing sector of the petroleum industry.
  • Drawworks
    - The hoisting mechanism on a drilling rig which spools off or takes in the drilling line and thus raises or lowers the drill string and bit.
  • Drill bit
    - The drilling tool that cuts through rock strata.
  • Drill pipe
    - Steel pipe sections, approximately 9.5 meters long, that are screwed together to form a continuous pipe extending from the drilling rig to the drilling bit at the bottom of the hole. Rotation of the drill pipe and bit causes the bit to bore through the rock.
  • Drill string
    - A column or string of drill pipe. The drill string carries the mud down to, and rotates, the drill bit.
  • Drilling
    - The operation that involves boring a hole through overlying geological horizons to the target zone(s) to determine if oil or gas is present in commercial quantities, and to convey oil and gas to the surface if found in commercial quantities.
  • Drilling mud
    - Specialized mud mixed at the drill site and pumped down the drillstring and up the annulus to prevent blowouts, remove cuttings and cool and lubricate the bit.
  • Drillstem test
    - A method of sampling fluid from a formation using a tool attached to the drillstem; the sample is used to assess the type and volume of fluids in the formation as well as their pressure and rate of flow.
  • Dry hole
    - An unsuccessful well; a well not capable of producing commercial quantities of oil or gas.

  • E
  • Electric well log
    - A record of electrical characteristics, primarily resistivity, of formations that have been drilled. Crude oil and natural gas are more electrically resistive than water, therefore rock with oi and gas filled pores registers a higher resistivity. Electric logs are used to identify the formations, determine the nature and amount of fluids they contain, and estimate their depth.
  • Enhanced oil recovery (EOR)
    - Any method that increases oil production by using techniques or materials that are not part of normal pressure maintenance or water flooding operations. For example, natural gas or carbon dioxide can be injected into a reservoir to "enhance" or increase oil production.
  • Established reserves
    - Generally defined as proved reserves plus one half probable reserves.
  • Exploration
    - The act of searching for potential subsurface reservoirs of gas or oil. Methods include the use of magnetometers, gravity meters, seismic exploration, surface mapping, and exploratory drilling.
  • Exploratory well
    - A well drilled either in search of a new, as yet undiscovered accumulation of oil and gas, or in an attempt to significantly extend the limits of a known reservoir.
  • Extraction loss
    - The reduction in volume of natural gas resulting from the removal of the natural gas liquid constituents at the processing plant. See also shrinkage.


  • F
  • Field
    - The geographical area encompassing a group of one or more underground petroleum pools sharing the same or related infrastructure.
  • Field pressure
    - The pressure of the natural gas as it is found in the underground formations from which it is produced.
  • Field price
    - The amount received by petroleum producers after deducting transportation and distribution costs.
  • Fish
    - An object left in the well bore during drilling or workover operations that must be recovered or bypassed before work can proceed.
  • Fishing
    - The term encompasses both the special equipment and the special procedures required to remove undesirable objects from the well bore.
  • Flaring
    - Controlled burning of natural gas that cannot be processed for sale because of technical or economic reasons. The biggest portion is solution gas flaring, which involves the burning of natural gas produced along with crude oil and bitumen. Flaring contributes primarily to emissions of sulphur dioxide and greenhouse gases. Depending on the combustion efficiency of the flare, there may be other compounds produced in very small quantities, some of which are considered to be toxic.
  • Formation
    - A designated subsurface layer that is composed throughout of substantially the same kind of rock or rock types.
  • Fossil fuel
    - Fuels sourced from plant and animal matter that have undergone transformation through heat and pressure.
  • Fractional distillation
    - The process of separating petroleum into its component parts or fractions, such as heavy gas oils, light gas oils, kerosene, naphtha and light gasoline.
  • Fracturing (or fracing)
    - A reservoir stimulation technique in which fluids are pumped into a potentially productive formation under high pressure to create or enlarge fractures allowing the oil or gas to flow from the zone at higher rates. In some operations proppants such as frac sand are injected with the frac fluid to help hold the rock fractures open.
  • Froth
    - A mixture of air, water and bitumen that rises to the surface of the primary separation vessel in the oilsands extraction process


  • G
  • Gas cycling
    - A petroleum recovery process that takes produced gas and condensate and injects it back into the reservoir to increase pressure and increase the production of natural gas liquids. See also repressuring.
  • Gasoline
    - One of the lightest products of fractional distillation.
  • Gathering lines
    - Pipelines that move raw petroleum from wellheads to processing plants and transmission facilities.
  • Gathering system
    - A system of small-diameter plastic or steel pipes (gathering lines) transporting natural gas from producing wells to field facilities.
  • Geochemistry
    - The science of chemistry applied to rocks and minerals; geochemists analyze the contents of subsurface rocks for the presence of organic matter associated with oil deposits.
  • Geological trap
    - Any geological structure that stops the migration of natural gas, crude oil and water through subsurface rocks, causing the hydrocarbons to accumulate into pools in the reservoir rock.
  • Geophones (or jugs)
    - Sensitive vibration-detecting instruments used in conducting seismic surveys; marine versions are known as hydrophones.
  • Geophysical survey
    - Searching and mapping the subsurface structure of the earth's crust using geophysical methods to locate probable reservoir structures capable of producing commercial quantities of natural gas and/or crude oil.
  • Gun perforator
    - A device that creates small holes through the casing, cement and into the producing formation of a well. The holes provide channels for gas and/or crude oil to flow into the well.
  • Gusher
    - A well that comes in with such great pressure that the oil or gas blows out of the wellhead like a geyser; gushers are rare today because of improved drilling technology, especially the use of drilling mud to control downhole pressure.


  • H
  • Heavy oil
    - Oil including some oil that will flow, however slowly, but most heavy oil requires heat or dilution to flow to a well or through a pipeline.
  • Horizontal drilling
    - Drilling horizontally through a reservoir to increase the exposure of the formation to the well.
  • Horizontal laterals
    - A series of horizontal drainage wells branching off from a horizontal wellbore.
  • Hydrocracking (refining)
    - A refining process which adds hydrogen to the carbon-rich molecules of heavier oil, in the presence of a catalyst, to produce a higher proportion of gasoline and diesel fuel.
  • Hydrocracking (upgrading)
    - A process in which bitumen is heated and hydrogen added under high pressure to break down the large hydrocarbon molecules into simpler, smaller compounds
  • Hydrotransport
    - A process that uses hot water to transport oil sands excavated at oil sands mining projects through a pipeline to a processing plant.
  • Hydrotreating
    - The process of adding hydrogen to heavy oil or bitumen molecules during the upgrading process.


  • I
  • In-line inspection tools
    - Cylinder-shaped devices, fitted with electronic sensors, that locate pipeline wall weaknesses before they can progress to the point of causing a leak
  • In-situ
    - In-situ is defined as meaning in its original place or in position. In oil sands production, in-situ recovery refers to various methods used to recover deeply buried bitumen deposits. These methods includisteam injection, solvent injection, cold heavy oil with sand and firefloods.
  • Infill drilling
    - Wells drilled between established producing wells on a lease in order to increase production from the reservoir.
  • Infill well
    - Any well that is drilled on a closer-than-normal well spacing pattern or requirement. Also, any well drilled between existing wells producing from the same reservoir.
  • Injection (oil and gas)
    - Injection enhancement technique wherein water or other substances are injected into an oil field to improve production. Also, the reinjectiong of natural gas into an oil field to maintain reservoir pressure.
  • Injection well
    - A well used for injecting air, water, carbon dioxide, steam or fluids into an underground formation.


  • J
  • Jackknife or folding mast
    - The type of mast on a drilling rig that can be folded for moving, as opposed to the standard derrick, which has to be completely dismantled and re-erected.
  • Joint implementation
    - A means of reducing global greenhouse gas emissions whereby a country receives credit for supporting emissions reductions elsewhere � for example, planting trees or replacing inefficient power generation facilities in developing countries.


  • K
  • Kelly
    - The first and sturdiest joint of the drill string in conventional rotary drilling rigs; a thick-walled, hollow steel forging with four flat sides that fits into a square hole in the rotary table.
  • Kerosene
    - A light product of fractional distillation used to make jet fuel and stove oil.
  • Kick
    - A kick occurs when the reservoir pressure of a formation exceeds the hydrostatic pressure of the mud in the drill string, creating the potential for a well to blow out of control.


  • L
  • Land
    - In the petroleum industry, "land" often refers to the oil and gas rights on a particular area of land. For example, in a "land sale," the oil and/or gas rights are "sold" (although in reality the rights are leased).
  • Light crude oil
    - Liquid petroleum which has a density less than 0.870 grams per cubic centimetre and flows freely at room temperature.
  • Limestone
    - Calcium carbonate-rich sedimentary rocks in which oil or gas reservoirs are often found.
  • Linepack
    - The volume of gas which is needed to be kept in the pipe of a gathering, transmission or distribution system in order to ensure the functioning of the system. Linepack can sometimes be used for short-term temporary storage of additional gas supplies.
  • Logs
    - Detailed depth-related records of certain significant characteristics of an oil or gas reservoir; obtained by lowering measurement instruments into a well.
  • Looping
    - A method of increasing capacity on a pipeline: a new section of pipeline is constructed parallel to an existing pipeline over any part or the whole length of the exisiting pipeline.


  • M
  • Manufactured gas
    - A gas obtained by destructive distillation of coal, by the thermal decomposition of oil, or by the reaction of steam passing through a bed of heated coal or coke. Examples are coal gases, coke or oven gases, producer gas, blast furnace gas, blue (water) gas, or carbureted water gas. Also known as syngas.
  • Marker crude
    - A specific crude oil, usually a blended crude with defined properties such as API gravity, sulphur content, etc., used as a reference for pricing other crude oils. Typical benchmark crudes are West Texas Intermediate (WTI), Brent (North Sea), Arab Light and Edmonton Par crude. As the price of the benchmark crude fluctuates, other crude oils from the same geographic area move up and down, depending on their properties relative to the benchmark and on supply and demand. Also known as benchmark crude.
  • Maximum efficient rate (MER)
    - The maximum rate at which natural gas and crude oil can be produced without excessive decline of reservoir energy or a loss in ultimate production.
  • Measurement-while-drilling (MWD) tool
    - Technology that transmits information from downhole measuring devices to the surface while drilling is ongoing.
  • Medium crude oil
    - Liquid petroleum with a specific gravity between that of light oil, 0.875 and heavy oil, 0.92.
  • Midstream
    - Primarily the processing, storage and transportation sector of the energy industry.
  • Migration
    - The movement of natural gas, crude oil and/or water through porous and permeable rock.
  • Miscible flood
    - A method of tertiary recovery of oil involving injection of carbon dioxide, or solvents such as ethane, propane and butane which mix with the oil to reduce surface tension and viscosity.
  • Mousehole
    - A hole drilled to the side of the wellbore to hold the next joint of drill pipe to be used; when this joint is pulled out and screwed onto the drill string, another joint of pipe is readied and slipped into the mousehole to await its turn.
  • Mud
    - Specialized fluid mixed at the drill site and pumped doun the drillstring and up the annulus to prevent blowouts, remove cuttings from the hole and to lubricate the drilling bit.
  • Mud motor
    - A downhole drilling motor that is powered by the force of the drilling mud pushed through the motor by the mud pumps at the surface.
  • Multiple entry
    - A technique for drilling several horizontal wells from a single vertical, directional or horizontal wellbore.
  • Multiple zone well completion
    - Completion of a well in such a way that production is obtained from several different formations.


  • N
  • Naphtha
    - A light fraction of crude oil used to make gasoline.
  • Natural gas liquids (NGLs)
    - Liquids obtained during production of natural gas, comprising ethane, propane, butane and condensate.
  • Nitrous oxide (N20)
    - A very potent greenhouse gas which has a large number of natural sources and is a secondary product of the burning of organic material and fossil fuels.
  • Non-associated gas
    - Natural gas that is produced from reservoirs that contain only natural gas and therefore not associated with crude oil production.
  • Non-conventional crude oil
    - Heavy crude oil that is too thick to flow in its natural state and cannot be produced by conventional means, but must be heated or diluted first, such as oil sands bitumen. More commonly known as unconventional crude oil.


  • O
  • Octane
    - A performance rating of gasoline; the higher the octane number, the greater the anti-knock quality of the gasoline. Knocking is the result of abnormal combustion in an internal combustion engine.
  • Oil sands
    - Naturally-occurring mixtures of bitumen, water, sand and clay.
  • Open pit
    - A method of surface mining where the coal seams or oil sands are too deep for strip mining but accessible from deep excavations
  • Operator
    - The company responsible for managing an exploration, development or production operation.
  • Orphan wells
    - Well sites for which the license operators have ceased to exist or cannot be traced.
  • Outcrop
    - Bedrock which is exposed at the earth�s surface


  • P
  • Packers
    - Expanding rubber diaphragms used to seal off portions of the wellbore.
  • Perforate
    - Creating holes in the casing to allow hydrocarbons to flow into the wellbore for production; usually usually accomplished by shooting hardened metal rods powered by explosive charges through the casing using a perforating gun lowered down the well bore.
  • Perforating gun
    - A special tool lowered down the well bore to shoot holes in the well�s casing into the producing formation to allow hydrocarbons to flow into the well.
  • Permeability
    - The capacity of a substance (such as rock) to transmit a fluid, such as crude oil, natural gas, or water. The degree of permeability depends on the number, size, and shape of the pores and/or fractures in the rock and their interconnections. It is measured by the time it takes a fluid of standard viscosity to move a given distance. The unit of permeability is the Darcy.
  • Petrochemicals
    - Chemicals derived from petroleum that are used as feedstocks for the manufacture of a variety of plastics and other products such as synthetic rubber.
  • Petroleum
    - A naturally occurring mixture composed predominantly of hydrocarbons in the gaseous or liquid phase.
  • Pig
    - A cylindrical device inserted into a pipeline to inspect the pipe or to sweep the line clean of water, rust or other foreign matter; pipeline inspection and cleaning devices are called pigs because early models squealed as they moved through the pipe. A �smart pig� is also equipped to find corrosion, cracks or weakness in the welding.
  • Pinnacle reef
    - A conical formation, higher than it is wide, usually composed of limestone, in which hydrocarbons might be trapped.
  • Pipeline
    - All parts of the physical facility through which gas is moved in transportation, including pipe, valves, and other equipment attached to the pipe, compressor units, metering stations, regulator stations, delivery stations, holders, and fabricated assemblies.
  • Pooling agreement
    - When the boundaries of two or more oil or gas leases do not coincide with the drill spacing unit, then a pooling agreement is needed among the lease holders before the regulatory authority will grant a drill permit.
  • Porosity
    - The ratio of the aggregate volume of pore spaces in rock or soil to its total volume, usually stated as a per cent.
  • Potential resources
    - The volume of natural gas or crude oil that is thought to exist based on geological knowledge, but has not been proven to exist though geophysical techniques or drilling.
  • Precambrian
    - Formed prior to the onset of the Cambrian era approximately; the time span lasting from 4.5 billion to 600 million years ago.
  • Pressure maintenance
    - The process of injecting water or produced natural gas back into a reservoir to prevent the reservoir pressure from decreasing.
  • Primary recovery
    - Producing oil by using either reservoir pressure or simple pumps.
  • Probable reserves
    - Reserves believed to exist with reasonable certainty based on geological information.
  • Production casing
    - The last string of casing set in a well; production casing is tubular steel pipe connected by threads and couplings that lines the total length of the wellbore to ensure safe control of production, prevent water from entering the wellbore and keep rock formations from �sloughing� into the wellbore.
  • Production tubing
    - Steel pipe inside the casing used to flow the petroleum from the producing zone to the surface.
  • Productive capacity
    - The estimated maximum volume which can be produced from known reserves based on reservoir characteristics, economic considerations, regulatory limitations and the feasibility of infill drilling or additional production facilities; also known as available supply.
  • Proppant
    - Sand, or ceramic or resin beads pumped into a wellbore at the end of the fracturing process to prop open newly induced fractures and enhance permeability.
  • Prospect
    - A geographical area that exploration has shown contains sedimentary rocks and structures favorable for the presence of crude oil or natural gas.
  • Proved reserves
    - Reserves that can be economically produced with a large degree of certainty from known reservoirs using existing technology.
  • Pumpjack
    - A device used to bring oil to the surface by raising and lowering a string of rods connected to a downhole pump.


  • Q
  • Quad
    - An energy quantity of one quadrillion BTUs (1,055 petajoules), which is approximately the energy equivalent contained in one trillion cubic feet of natural gas. 


   R

  • Rathole
    - A slanted hole drilled near the wellbore to hold the kelly joint when not in use; the kelly is unscrewed from the drill string and lowered into the rathole.
  • Raw natural gas
    - A mixture containing methane plus all or some of the following: ethane, propane, butane, condensates, nitrogen, carbon dioxide, hydrogen sulphide, helium, hydrogen, water vapour and minor impurities. Raw natural gas is the gas found naturally in the reservoir prior to processing.
  • Receipt point
    - The location where gas enters a transporter's system from a well, plant or pipeline interconnect.
  • Recoverable resources
    - Hydrocarbon reserves that can be produced with current technology including those not economical to produce at present.
  • Reforumulated gasoline/fuel
    - Fuel whose physical or chemical property specification has been changed.
  • Repressuring
    - Forcing gas, under pressure, into a crude oil reservoir in an attempt to increase the recovery of crude oil. This can also be achieved using water.
  • R/P Ratio
    - Thereserves-to-production ratio measures the length of time current proved or established reserves would last if current production rates were maintained and no new reserves were added. Essentially, it measures the "ready inventory" of crude oil or natural gas.
  • Reserves
    - Recoverable portion of resources available for use based on current knowledge, technology and economics.
  • Reservoir (Oil and Gas)
    - A porous and permeable underground rock formation containing a natural accumulation of crude oil or natural gas that is confined by impermeable rock or water barriers, and is separate from other reservoirs.
  • Residuum
    - A heavy, black, tar-like substance that remains after crude oil has been fully refined to distil all usable fractions or components.
  • Rod string
    - A string of steel rods used to provide up-and-down motion for a bottom-hole pump to lift oil to the surface.
  • Rotary bit
    - The cutting tool attached to the lower end of the drill string of a rotary drilling rig. As the drill string rotates, the bit chews through the formation.
  • Rotary drilling
    - A method for drilling wells using a cutting bit attached to a revolving drill string.
  • Rotary pump
    - A downhole pump used to bring oil to the surface which operates by a rotary action rather than an up-and-down motion.
  • Rotary rig
    - A modern drilling unit capable of drilling a well with a bit attached to a rotating column of steel pipe.
  • Rotary table
    - A heavy, circular casting mounted on a steel platform just above the rig floor which rotates the drill string and thus turns the bit.


  • S
  • Salt cavern
    - An underground natural gas storage cavern which has been developed in a salt dome by the solution mining process.
  • Sandstone
    - A compacted sedimentary rock composed mainly of quartz or feldspar; a common rock in which oil, natural gas and/or water accumulate. Coarser than shale or siltstone.
  • Secondary recovery
    - Injecting water or natural gas into a producing reservoir to maintain reservoir pressure and enhance recovery of oil.
  • Sedimentary basin
    - A geographical area in which much of the rock is sedimentary (as opposed to igneous or metamorphic) and is therefore likely to contain hydrocarbons.
  • Sedimentary rocks
    - Rocks formed by the accumulation of sediment or organic materials and therefore likely to contain hydrocarbons. Includes sandstone, limestone, siltstone and shale.
  • Seismic method
    - A method of mapping subsurface structures using data derived from transmitting acoustic energy into the earth and recording the energy reflected back from subsurface geological boundaries.
  • Seismic surveys
    - Running one or more 2-D or 3-D seismic lines over a large area and using the acquired data to create detailed models of underlying geological formations and to find oil and natural gas reservoirs.
  • Service rig
    - A truck-mounted rig, usually smaller than a drilling rig, that is brought in to complete a well or to perform maintenance, replace equipment or improve production.
  • Set casing
    - To install steel pipe or casing in a well bore. An accompanying operation is the cementing of the casing in place by surrounding it with a wall of cement extending for all or part of the depth of the well.
  • Shale
    - A sedimentary rock formed from clay and fine grained sediment.
  • Shale shaker
    - A vibrating screen for sifting out rock cuttings from drilling mud during drilling operations.
  • Shrinkage
    - The reduction in volume of wet natural gas due to the extraction of some of its constituents, such as hydrocarbon products, hydrogen sulphide, carbon dioxide, nitrogen, helium and water vapour.
  • Shut-in well
    - A well that has been completed but is not producing. A well may be shut-in for tests, repairs, to await construction of gathering lines, or better economic conditions.
  • Smart pig
    - Sophisticated instrument packages sent through pipelines to test for corrosion and buckling.
  • Smog
    - Brown summer haze that intermittently forms over some cities. It is comprised of ground-level ozone (nitrogen oxides, volatile organic compounds and fine particulates). Smog can be created by natural processes (such as forest fires and volcanoes) or human activities (such as the burning of fossil fuels). The name is derived from SMoke and fOG.
  • Solution gas
    - Natural gas that is disolved in crude oil in underground reservoirs. When the oil comes to the surface, the gas expands and comes out of the oil.
  • Sour gas
    - Raw natural gas with a relatively high concentration of sulphur compounds, such as hydrogen sulphide. All natural gas containing more than one per cent hydrogen sulphide is considered sour.
  • Sour oil
    - Oil containing sulphur compounds such as hydrogen sulphide.
  • Source rock
    - The rocks in which hydrocarbons are created or sourced from carbohydrates through heat and pressure. Source rocks are often black shales.
  • Spill
    - Controlled or accidental release of a substance to land or water (oil, emulsion, produced water or other liquids).
  • Steam injection
    - A technique in which steam is injected into a reservoir to reduce the viscosity of the crude oil. One of the in situ methods for producing bitumen.
  • Steam-assisted gravity drainage (SAGD)
    - An in situ method of producing heavy oil which involves two horizontal wellbores, one above the other. Steam is injected into the upper wellbore and softened bitumen is recovered from the lower wellbore.
  • Stimulation
    - Enhancing the production of a well; includes acidizing and fracturing the reservoir as well as removing wax and sand from the wellbore.
  • Straddle extraction plant
    - A gas processing plant located on or near a gas transmission line that removes natural gas liquids from the gas and returns it to the line.
  • Sulphur oxides (SOx)
    - Gases produced mostly from human activities (such as metal smelting, and fossil fuel combustion by factories, power plants and motor vehicles). Sulphur dioxide combines with water vapor to form sulphuric acid, a contributor to acid rain. Human exposure to sulphur dioxide emissions can also cause respiratory problems.
  • Surface casing
    - The first string of casing put into a well; it is cemented into place and serves to shut out shallow water formations and as a foundation for well control.
  • Surface rights
    - The rights to areas of land used for well pads, batteries, gas plants and service roads
  • Sweet crude oil
    - Crude oil containing less than 0.5 per cent sulphur.
  • Sweet gas
    - Raw natural gas with a relatively low concentration of sulphur compounds, such as hydrogen sulphide.
  • Sweeten
    - Remove hydrogen sulphide and carbon dioxide from sour gas to make it marketable.
  • Syngas
    - A fuel produced from solid hydrocarbons such as coal and petroleum coke. The process uses steam, air and controlled amounts of oxygen to break the solid down, and the resulting gas consists of vaying amounts of carbon monoxide and hydrogen.
  • Synthetic crude oil
    - A mixture of hydrocarbons, similar to crude oil, derived by upgrading bitumen from oil sands.


  • T
  • Tailings
    - Waste products from oil sands mining, extraction, and upgrading operations. Also solid waste left after uranium ore has been extracted from rock.
  • Tertiary recovery
    - Enhancing recovery using sophisticated methods such as miscible flooding or fire flooding.
  • Thermal electricity
    - Electricity generated from burning fossil fuels such as coal, natural gas and refined petroleum products; biomass such as wood, wood waste, pulping liquors and landfill methane; or other waste materials such as used tires.
  • Tight gas sands
    - Natural gas that is found in sandstone with low permeability.
  • Toluene
    - Clear, odorless, flammable liquid that has the characteristic aromatic odor of model airplane glue. It is added to gasoline to increase octane.
  • Top drives
    - Hydraulic or electric motors that are suspended in the derrick above the rig floor to rotate the drill string and bit.
  • Trap
    - The mechanism by which oil and gas are prevented from migrating out of the reservoir.
  • Tripping
    - The process of removing the drill string from the hole to change the bit and running the drill string and new bit back into the hole.
  • Trunk lines
    - Large-diameter pipelines that transport crude oil, natural gas liquids and refined petroleum products to refineries and petrochemical plants; some trunk lines also transport refined products to consuming areas.


  • U
  • Underbalanced drilling
    - Drilling where the hydrostatic pressure of the fluids in the wellbore is lower then the reservoir pressure; commonly used in tight reservoirs to avoid reservoir damage
  • Unitization
    - Process whereby owners of adjoining properties pool reserves into a single unit operated by one of the owners; production is divided among the owners according to the unitization agreement.
  • Upgraded crude oil
    - A blend of hydrocarbons similar to light crude oil produced by processing bitumen or heavy oil at a facility called an upgrader. (Also called synthetic crude oil.)
  • Upgrading
    - The process of converting heavy oil or bitumen into synthetic crude oil
  • Upstream
    - Relating to the exploration and production sector of the petroleum industry.
  • Upstream oil and gas industry
    - Refers to companies that explore for, develop and produce petroleum resources (in contrast, downstream refers to the refining and marketing components of the industry). 

    V
  • V-door
    - The opening in the derrick opposite the drawworks used for bringing in drill pipe and casing from the nearby pipe racks.
  • Vibroseis
    - Energy for seismic surveys generated by massive, truck-mounted, vibrating plates.
  • Viscosity
    - The resistance to flow or �stickiness� of a fluid.
  • Volatile organic compounds (VOCs)
    - Gases and vapours, such as benzene, released by petroleum refineries, petrochemical plants, plastics manufacturing and the distribution and use of gasoline; VOCs include carcinogens and chemicals that react with sunlight and nitrogen oxides to form ground-level ozone, a component of smog.


  • W
  • Well-logging instruments
    - Instruments lowered into a well to provide specific information on the charsacteristics of the reservoir.
  • Wellbore
    - A hole drilled or bored into the earth, usually cased with metal pipe, for the production of natural gas or oil.
  • Wellhead
    - The assembly of fittings and valve equipment used for producing a well and maintaining surface control of a well.
  • Wet gas
    - Raw natural gas with a relatively high concentration of natural gas liquids (ethane, propane, butane, and condensates).
  • Wildcat well
    - A well drilled in a previously unexplored area.
  • Wire line logs
    - Charts derived from devices lowered into the wellbore on a cable or wire line that measure permeability, porosity and electrical properties of reservoir fluids.
  • Wireline logging tools
    - Special tools or equipment, such as logging tools, packers or measuring devices, designed to be lowered into the well on a wireline (small-diameter steel cable). 

    X
  • Xylene
    - Aromatic hydrocarbon that forms the basis for many synthetic organic chemicals