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PSAC Areas


Conversion Factors




Alberta Activity Index (AAX)

This index, developed by the Alberta Treasury Board, closely tracks economic activity. It is a weighted average of the following nine monthly indicators: employment, average weekly earnings, retail trade, wholesale trade, manufacturing, new truck sales, housing starts, rigs drilling, and oil production.

Alberta Energy Company’s storage hub (AECO-C)

The AECO-C hub is a virtual trading point that sets the main pricing index for Albertan and Canadian natural gas.

AECO-C Price

The Natural Gas Exchange (NGX) volume-weighted average of transacted prices for all physically delivered natural gas in a calendar month; at the Alberta Nova Inventory Transfer (ABNIT) market centre.

Alberta Natural Gas Reference Price (ARP)

A monthly weighted average field price of all Alberta gas sales that is used for royalty purposes. The price is determined by the Alberta Department of Energy through a survey of actual sales transactions. Also known as the price of Alberta natural gas at the plant gate.

API gravity

A specific gravity scale developed by the American Petroleum Institute (API) for measuring the relative density or viscosity of various petroleum liquids.


When shippers desire to ship more oil or oil products in a given month than the pipeline can transport, shipper volumes are apportioned (reduced) based on the tariff in effect. Apportionment can be caused by factors such as growing supply, increased demand, pipeline reconfigurations, reduced pipeline capacity, or refinery maintenance.



Brent Blend (Brent)

A grade of light sweet crude oil derived from a mix of 15 different oil fields in the North Sea. Brent blend futures are traded on the Intercontinental Exchange Inc. (ICE) and are considered a global benchmark for oil prices.


Rock composed of broken fragments of mineral or rock cemented together by a finer-grained matrix. In the case of the McMurray Formation, mudstone breccias consist of large angular mud fragments within sands.


Brownfield projects are projects built where land has previously been developed or where there is room to expand an existing facility.


The location where a fuel is used by a consumer.


In addition to its normal scientific meaning, a mixture mainly of butanes that ordinarily may contain some propane or pentanes plus (Oil and Gas Conservation Act, section 1(1)(j)).



capital costs

Expenditures by a company to build, purchase, or upgrade physical assets such as land, equipment, and processing facilities.

carbon capture, utilization, and storage (CCUS)

A range of technologies and processes that capture carbon dioxide from industrial sources or directly from the atmosphere, and then utilized by injecting it into underground porous formations as part of CO2-enhanced oil recovery or used to produce manufactured goods.

carbon capture and storage (CCS)

A process similar to CCUS but excludes the utilization of carbon dioxide and instead it is injected into subsurface formations (e.g., saline aquifers or depleted oil and gas reservoirs) for permanent storage.

clean coal

Clean coal is coal that has been processed for export by washing raw coal to remove soil and rock sediment. While subbituminous coal is burned without any form of upgrading, both metallurgical and thermal bituminous coal are sent in raw form to a preparation plant to be processed into clean coal. On average, about 65% of raw metallurgical bituminous coal and less than 50% of raw thermal bituminous coal is recovered as clean coal in Alberta. Subbituminous raw coal and both types of clean bituminous coal are collectively known as marketable coal.


A combustible sedimentary rock that contains at least 50% by weight organic matter formed from plant or algal matter (Coal Conservation Act, section 1(1)(d)).

coalbed methane (CBM)

Naturally occurring dry gas, predominantly methane, produced during the transformation of organic matter into coal.

coal seam

A layered unit of coal and inorganic matter that contains less than one-third inorganic matter by volume and does not contain a layer of inorganic matter exceeding 0.3 metres in thickness (Coal Conservation Act, section 1(1)(e.1)).

cogeneration gas plant

A gas-fired plant used to generate both electricity and steam.

conventional resources

Conventional resources are those that have the necessary rock permeability and fluid viscosity to be commercially productive without the use of stimulation technology. These resources are buoyancy-driven deposits that accumulate in structural or stratigraphic traps.


Commingled flow describes the production of fluid from two or more separate zones through a single conduit.

compressibility factor

A correction factor for nonideal gas determined for gas from a pool at its initial reservoir pressure and temperature and, where necessary, includes factors to correct for acid gases.


A mixture mainly of pentanes and heavier hydrocarbons that may be contaminated with sulphur compounds, that

  • is recovered or is recoverable at a well from an underground reservoir and may be gaseous in its virgin reservoir state but is liquid at the conditions under which its volume is measured or estimated, or
  • is recovered from an in situ coal scheme and is liquid at the conditions under which its volume is measured or estimated (Oil and Gas Conservation Act, section 1(1)(k)).
crude bitumen

A naturally occurring viscous mixture, mainly of hydrocarbons heavier than pentane, that may contain sulphur compounds and that, in its naturally occurring viscous state, will not flow to a well (Oil Sands Conservation Act, section 1(1)(c)).

crude oil (conventional)

A mixture mainly of pentanes and heavier hydrocarbons that may be contaminated with sulphur compounds, that is recovered or is recoverable at a well from an underground reservoir and that is liquid at the conditions under which its volume is measured or estimated, and includes all other hydrocarbon mixtures so recovered or recoverable except raw gas, condensate, or crude bitumen (Oil and Gas Conservation Act, section 1(1)(o)).

crude oil (heavy)

Crude oil with a density greater than or equal to 900 kg/m3 and less than 925 kg/m3.

crude oil (light)

Crude oil with a density of 850 kg/m3 or less.

crude oil (light-medium)
Crude oil with a density less than 900 kg/m3.

crude oil (medium)

Crude oil with a density equal to 850 kg/m3 and less than 900 kg/m3.

crude oil (ultra-heavy)

Crude oil with a density of 925 kg/m3 or greater.              

crude oil (synthetic)

A mixture, mainly of pentanes and heavier hydrocarbons, that may contain sulphur compounds, and is derived from crude bitumen and that is liquid at the conditions under which its volume is measured or estimated, and includes all other hydrocarbon mixtures so derived (Oil and Gas Conservation Act, section 1(1)(zz)).

crude oil netback

An economic indicator of profitability expressed as a dollar value per unit of production. Crude oil netbacks are calculated from the price of West Texas Intermediate (WTI) crude oil at Chicago, less transportation and other charges to supply crude oil from the wellhead to the Chicago market. Alberta netback prices are adjusted for the U.S./Canadian dollar exchange rate, as well as crude quality differences.

cyclic steam stimulation (CSS)

A technique that produces bitumen by injecting steam into underground oil sands reservoirs (i.e., wells) to heat bitumen, separate it from the sand, and allow it to flow to the well and be produced.



datum depth

The approximate average depth relative to sea level of the midpoint of an oil or gas productive zone for the wells in a pool.


An engineering optimization process conducted by a company to improve efficiencies, reduce constraints limiting output at a facility, or both.

decline rate

The annual rate of decline in well productivity.

deep-cut facility

See NGL recovery (deep-cut gas facility).


The mass or amount of matter per unit volume.

density, relative (raw gas)

The density relative to air of raw gas upon discovery, determined by an analysis of a gas sample representative of a pool under atmospheric conditions.

developed reserves

Developed reserves are reserves that are expected to be recovered from existing wells and installed facilities. If facilities have not been installed, developed reserves are reserves that are expected to be recovered from existing wells where the cost required to put the reserves on production is relatively minor compared with the cost of drilling and completing a new well. There are two categories of developed reserves: producing and non-producing.

developed reserves (non-producing)

Developed non-producing reserves are reserves that either (1) have not been on production or (2) have previously been on production but are no longer being produced because the well is shut in and the date for when production is to resume is unknown.

developed reserves (producing)

Developed producing reserves are reserves that are expected to be recovered from completion intervals open at the time the reserves estimate was generated. These reserves may be currently producing or, if shut in, they must have previously been on production and the date for when production is to resume must be known with reasonable certainty.

development entity (DE)

An administrative unit consisting of multiple formations in a designated area described in an order of the AER. Within the DE, gas may be produced without segregation in the wellbore, subject to certain criteria specified in section 3.051 of the Oil and Gas Conservation Rules.


Lighter-viscosity petroleum products that are used to dilute crude bitumen for transport in pipelines.

discovery year

The year when drilling was completed for the well in which the oil or gas pool was discovered.

drainage areas (SAGD)

Area surrounding a well pair or multiple well pairs from which bitumen is produced.

drain wells

More than one event sequence (leg) in a multileg well is open to the same pool and is capable of production. The event sequence considered to be the main contributor of production carries the producing status. The other contributing events carry a drain status.



economic strip ratio

Ratio of waste (overburden material that covers mineable ore) to ore (coal or oil sands) used to define an economic limit below which it is economical to remove the overburden to recover the ore.

enhanced recovery/development

The increased recovery from a pool achieved by artificial means or by the application of energy extrinsic to the pool, which artificial means or application includes pressuring, cycling, pressure maintenance or injection to the pool of a substance or form of energy, but does not include the injection in a well of a substance or form of energy for the sole purpose of

  1. aiding in the lifting of fluids in the well, or
  2. stimulation of the reservoir at or near the well by mechanical, chemical, thermal, or explosive means (Oil and Gas Conservation Act, section 1(1)(r)).
established reserves

Those reserves recoverable under current technology and present and anticipated economic conditions specifically proved by drilling, testing, or production, plus the portion of contiguous recoverable reserves that are interpreted to exist from geological, geophysical, or similar information with reasonable certainty and independent of current commodity prices.


In addition to its normal scientific meaning, a mixture mainly of ethane that ordinarily may contain some methane or propane (Oil and Gas Conservation Act, section 1(1)(s)).


The process of liberating hydrocarbons (e.g., propane, bitumen) from their source (e.g., raw gas, mined oil sands).




A raw material supplied to a refinery, oil sands upgrader, or petrochemical plant.

  1. The general surface area or areas underlain or appearing to be underlain by one or more pools, or
  2. the subsurface regions vertically beneath a surface area or areas referred to in subclause (i) (Oil and Gas Conservation Act, section 1(1)(x)).
field (gas) plant

A natural gas facility that processes raw gas and produces a marketable product that meets pipeline specifications. These plants, located near the gas source, remove impurities, such as water and hydrogen sulphide, from the raw gas stream and may also extract natural gas liquids. See also NGL recovery (extraction plant).

field plant gate

The point at which the gas exits the field plant and enters a pipeline.


A rock unit with comparable lithology, facies, or other similar properties that allows geologists to map, describe, and name it. The primary unit of lithostratigraphy. Two or more formations can be packaged together into a group and formations can be subdivided into members.

fractionation plant

See NGL recovery (fractionation plant).

free on board (FOB) price

FOB represents an international pricing point where, after a commodity is loaded on a ship, the liability for and the cost of shipping the commodity transfers from a seller to a buyer.




Raw gas, synthetic coal gas or marketable gas or any constituent of raw gas, synthetic coal gas, condensate, crude bitumen or crude oil that is recovered in processing and that is gaseous at the conditions under which its volume is measured or estimated (Oil and Gas Conservation Act, section 1(1)(y)).

gas (associated)

Gas in a free state in communication in a reservoir with crude oil under initial reservoir conditions.

gas (dry)

Raw or processed gas that contains little to no natural gas liquids.

gas (liquefied petroleum gas)

Mixes containing butanes and propane are referred to as liquefied petroleum gas (LPG) and are used primarily as fuel sources for cooking and heating appliances and for vehicles.

gas (liquids-rich)

Raw gas that contains a relatively high concentration of natural gas liquids.

gas (marketable)

A mixture mainly of methane originating from raw gas, if necessary through the processing of the raw gas for the removal or partial removal of some constituents, and that meets specifications for use as a domestic, commercial or industrial fuel or as an industrial raw material (Oil and Gas Conservation Act, section 1(1)(ee)). Marketable gas is measured at standard conditions of 101.325 kPa and 15°C.

gas (nonassociated)

Gas that is not in communication in a reservoir with an accumulation of liquid hydrocarbons at initial reservoir conditions.

gas (raw)

A mixture containing methane, other paraffinic hydrocarbons, nitrogen, carbon dioxide, hydrogen sulphide, helium and minor impurities, or some of them, that is recovered or is recoverable at a well from an underground reservoir and is gaseous at the conditions under which its volume is measured or estimated (Oil and Gas Conservation Act, section 1(1)(tt)).

gas (solution)

Gas that is dissolved in crude oil under reservoir conditions and evolves as a result of pressure and temperature changes.

gas (sour)

Natural gas that contains measureable amounts of hydrogen sulphide (H2S). For this report, measurable refers to volumes of H2S in excess of 0.01%.

gas (wet)

Raw or processed gas that contains natural gas liquids.

gas-oil ratio (initial solution)

The volume of gas (in cubic metres, measured under standard conditions) contained in one stock-tank cubic metre of oil under initial reservoir conditions.

good production practice (GPP)

Production of crude oil or raw gas at a rate

  1. not governed by a base allowable, but
  2. limited to what can be produced without adversely and significantly affecting conservation, the prevention of waste, or the opportunity of each owner in the pool to obtain his share of production (Oil and Gas Conservation Rules, section 1.020(2)9). This practice is authorized by the AER either to improve the economics of production from a pool and thus defer its abandonment or to avoid unnecessary administrative expenses associated with regulation or production restrictions where this serves little or no purpose.

Greenfield projects are projects built on land that has not previously been used and has no existing components or structures.

gross heating value (of dry gas)

The heat liberated by burning moisture-free gas at standard conditions and condensing the water vapour to a liquid state.



halo play

A halo play is an extension of a conventional reservoir that does not meet the traditional cutoffs for conventional reservoirs. In halo plays, the source rock is not the reservoir. The permeability of a halo play is often less than, but can exceed, 0.1 millidarcy (mD). The permeability of a halo play is generally higher than the permeability in tight or shale plays. In order to produce the resources within a halo play, more advanced completion techniques are needed, such as horizontal multistage fracturing.

Henry Hub

A distribution hub on a main natural gas pipeline system in the United States near Erath, Louisiana. It is the pricing point for natural gas futures contracts traded on the New York Mercantile Exchange (NYMEX).

horizontal well

A well in which the lower part of the wellbore is drilled parallel to the zone of interest.

hydraulic fracturing

Hydraulic fracturing is the process of pumping fluid into a wellbore to create enough pressure to crack, or fracture, the rock layer. The fluid usually contains a “proppant,” like sand, that helps keep the fractures open to allow oil and gas to be produced to the well.

hydraulic multistage fracturing

The application of hydraulic fracturing over multiple segments within a well leg, starting at the “toe,” or near-end point of the drilling leg, and moving backwards to the “heel,” or vertical portion of the well leg. This drilling and completion technique is commonly used to access low-permeability reservoirs. It significantly improves production because the wellbore is able to access a greater length of the reservoir.


inclined heterolithic stratification (IHS)

IHS deposits consist of dipping interbedded sands and muds. IHS constitute a significant portion of the McMurray Formation.

initial established reserves

Established reserves prior to the deduction of any production.

initial volume in place

The volume or mass of crude oil, crude bitumen, raw natural gas, or coal calculated or interpreted to exist in the ground before any quantity has been produced.




A carbonate sedimentary rock predominantly composed of calcite of organic, chemical, or detrital origin.  Minor amounts of dolomite, chert, and clay are common in limestones.

liquefied natural gas (LNG)

Natural gas that has been converted to liquid form at deep freezing temperatures for storage and overseas transportation.



marketable bitumen

Upgraded and nonupgraded bitumen available to be used as refinery feedstock.

maximum day rate

The operating day rate for gas wells when they are first placed on production. Estimating the maximum day rate requires the average hourly production rate. For each well, the annual production is divided by the hours that the well produced in that year to obtain the average hourly production for the year. This hourly rate is then multiplied by 24 hours to yield an estimate of a full-day operation of a well, which is referred to as the maximum day rate.

maximum recoverable thickness

The assumed maximum operational reach of underground coal mining equipment in a single seam.

mean formation depth

The approximate average depth below kelly bushing of the midpoint of an oil or gas productive zone for the wells in a pool.


In addition to its normal scientific meaning, a mixture mainly of methane that ordinarily may contain some ethane, nitrogen, helium, or carbon dioxide (Oil and Gas Conservation Act, section 1(1)(ff)).

multilateral well

A well where two or more production holes, usually horizontal in direction with reference to the zone of interest, are drilled from a single surface location.



natural gas

See gas.

natural gas liquids (NGLs)

Ethane, propane, butanes, pentanes plus, or a combination of these, obtained from the processing of raw gas or condensate.

NGL recovery (deep-cut gas facility)

A natural gas processing facility capable of extracting ethane and other natural gas liquids.

NGL recovery (extraction plant)

A natural gas processing facility that can remove natural gas liquids from raw or processed natural gas. Extraction plants can remove an NGL mix but cannot split the natural gas liquids into separate components. See also field (gas) plant.

NGL recovery (fractionation plant)

A natural gas processing facility that takes a natural gas liquids stream and separates out its different components: ethane, propane, butane, and pentanes plus.

NGL recovery (shallow-cut gas facility)

A natural gas processing facility that extracts propane, butane, and pentanes plus.

NGL recovery (straddle plant)

A reprocessing plant on major natural gas transmission lines near Alberta’s borders that extracts natural gas liquids (NGLs) from marketable gas. Most plants are deep-cut facilities that then ship an NGL stream to fractionation plants in central Alberta.

nonroutine venting

Nonroutine venting can be planned or unplanned, such as in the case of an emergency or when equipment in a facility is depressurized.

nonupgraded bitumen

Nonupgraded bitumen refers to crude bitumen that is blended with a lighter-viscosity product (referred to as a diluent) to meet specifications for transport through pipelines.




Natural gas produced from upgrading bitumen. This gas is typically rich in natural gas liquids and olefins.


Condensate, crude oil, or synthetic coal liquid or a constituent of raw gas, condensate, or crude oil that is recovered in processing, that is liquid at the conditions under which its volume is measured or estimated (Oil and Gas Conservation Act, section 1(1)(hh)).

oil sands
  1. sands and other rock materials containing crude bitumen,
  2. the crude bitumen contained in those sands and other rock materials, and
  3. any other mineral substances, other than natural gas, in association with that crude bitumen or those sands and other rock materials referred to in subclauses (i) and (ii) (Oil Sands Conservation Act, section 1(1)(l)).
oil sands areas

For administrative purposes, the geological formations and the geographic areas in Alberta that contain bitumen are designated as oil sands areas. There are three oil sands areas in Alberta: Athabasca, Cold Lake, and Peace River.

oil sands deposit

A natural reservoir containing or appearing to contain an accumulation of oil sands separated or appearing to be separated from any other such accumulation (Oil and Gas Conservation Act, section 1(1)(jj)).

operating costs

Includes both fixed and variable costs associated with running a project on a day-to-day basis.


When used in reference to mining, overburden is the thickness of the material above a mineable occurrence of coal or bitumen; otherwise, it is the soil and loose material between the land’s surface and solid bedrock.

overnight rate

The overnight rate is the interest rate at which major financial institutions borrow and lend one-day (or “overnight”) funds among themselves; the Bank of Canada sets a target for that rate. This target for the overnight rate is often referred to as the bank’s key interest rate or key policy rate.




A volume of genetically related rock containing no extensive period of erosion or non-deposition, bounded by flooding surfaces. These surfaces are sharp contacts between rocks denoting a water deepening event.

pay (net)

The thickness of rock that contributes to economically viable production. Unproductive or uneconomic layers are not included in the net pay thickness.

pay thickness (average)

The bulk rock volume of a reservoir of crude oil, bitumen, or gas divided by its area.

pentanes plus

A mixture mainly of pentanes and heavier hydrocarbons that ordinarily may contain some butanes and that is obtained from the processing of raw gas, condensate or crude oil (Oil and Gas Conservation Act, section 1(1)(mm)).


Permeability is defined as the ability, or measurement of a rock’s ability, to transmit fluids. Typically measured in units or subunits of darcies.


A geological play can be defined as a set of known or estimated oil or gas accumulations (pools and deposits) within a petroleum system that share similar geological, geographic, and temporal properties, such as a source rock, migration pathways, timing, trapping mechanism, and hydrocarbon type.

  1. a natural underground reservoir containing or appearing to contain an accumulation of oil or gas, or both, separated or appearing to be separated from any other such accumulation, or
  2. in respect of an in situ coal scheme, that portion of a coal deposit that has been or is intended to be converted to synthetic coal gas or synthetic coal liquid (Oil and Gas Conservation Act, section 1(1)(oo)).      
porosity (effective)

Effective porosity is defined as the volume of the interconnected pores that contribute to fluid flow in a reservoir. The effective porosity of a reservoir is calculated by subtracting the fluids bound on clays and shales and within isolated pores from the total porosity. Therefore, effective porosity is less than or equal to total porosity.

porosity (total)

Total porosity is defined as being either the percentage of pore volume or void space or the volume within a reservoir that can contain fluids. The total porosity does not necessarily contribute to fluid flow in a reservoir.

pressure (initial)

The reservoir pressure at the reference elevation of a pool upon discovery.

probable reserves

Probable reserves are additional reserves with a lower certainty of recovery than proved reserves.

proved reserves

Proved reserves are reserves that can be estimated with a high degree of certainty to be recoverable. It is likely that the actual remaining quantities recovered will exceed the estimated proved reserves.

proved plus probable reserves

Proved plus probable reserves is the sum of proved and probable reserves categories. The sum is the best possible estimate for the volume of reserves.


In addition to its normal scientific meaning, a mixture mainly of propane that ordinarily may contain some ethane or butanes (Oil and Gas Conservation Act, section 1(1)(rr)).



recovery (enhanced)

See enhanced recovery.

recovery (pool)

In gas pools, the fraction of the in-place resources of gas expected to be recovered under the subsisting recovery mechanism.

recovery (primary)

Recovery of oil by natural depletion processes only, measured as a volume that is recovered or as a fraction of the in-place oil.

refined petroleum products

End products in the refining process.

refinery light ends

Light oil products produced at a refinery; includes gasoline and aviation fuel.

refinery utilization

Refinery utilization shows the ratio of throughput to capacity.

remaining established reserves

Initial established reserves less cumulative production.


Product that has been removed from Alberta.

reprocessing facilities

Gas processing plants used to extract ethane and natural gas liquids from marketable natural gas. Such facilities, also referred to as straddle plants, are located on major natural gas transmission lines.


Estimates of remaining quantities of petroleum anticipated to be recoverable from known accumulations as of a given date, using technology that is known, either currently available or in use, and commercially possible.


Reservoirs are any subsurface rocks that are able to store fluids (water, oil, and gas) inside their pores or fractures.


Quantities of petroleum estimated to exist originally in naturally occurring accumulations, including all known and estimated quantities yet-to-be discovered.

routine venting

Routine venting happens on a regular basis as part of normal operations. It can include venting from production casing vents, waste vents, and tanks.



sales gas

A volume of gas sold over a period of time. This gas may be augmented with gas from storage.

saturation (gas)

The fraction of pore space in the reservoir rock occupied by gas upon discovery.

saturation (water)

The fraction of pore space in the reservoir rock occupied by water upon discovery.


The act or activity of injecting a fluid (such as carbon dioxide) into a subsurface porous formation and permanently trapping the fluid.


The AER uses the criteria published in Bulletin 2010-28: Zones Eligible for Shale Gas Fluid Codes. As a general guide, a mudstone/shale succession may be defined as being one or more of the following:

  1. a laminated rock with greater than 67% clay-sized minerals, often with fissility.
  2. a blocky or massive fine grained sedimentary rock in which the proportion of clay is approximately equal to or greater than silt-sized particles.
  3. a fine grained, low permeability clastic, carbonate, or mixed-lithology rock of which the exact composition is unknown; however, on a geophysical log, the response of the production interval is uniformly shaley.
shale gas

The naturally occurring gas produced from organic-rich, fine-grained rocks.

shale NGLs

The naturally occurring mixture of natural gas liquids produced from organic-rich, fine-grained rocks.

shale oil

A naturally occurring mixture of mainly pentanes and heavier hydrocarbons produced from organic-rich, fine-grained rocks.

shrinkage factor (initial)

The volume occupied by one cubic metre of oil from a pool measured at standard conditions after flash gas liberation consistent with the surface separation process and divided by the volume occupied by the same oil and gas at the pressure and temperature of a pool upon discovery.


A suitable mixture of hydrocarbons ranging from methane to pentanes plus but consisting largely of methane, ethane, propane, and butanes for use in enhanced-recovery operations.

source rock

A source rock is a rock rich in organic matter which, if heated sufficiently, will generate oil or gas. Due to advancements in technology, source rocks may also be targeted as reservoir rocks through the use of horizontal drilling and hydraulic multistage fracturing.

specification product

A crude oil or refined petroleum product with defined properties.

station 2

Station 2 is the trading point located at the physical intersection of many of the gas outputs from northern B.C. gas wells and processing plants.

steam-assisted gravity drainage (SAGD)

A method of in situ recovery where steam is injected into a horizontal well to heat the bitumen in a reservoir and allow it to flow; gravity pulls the heated bitumen to a second horizontal well positioned below the first and the bitumen is then produced to the surface.

steam-assisted gravity drainage (SAGD) well pad

A well pad made up of multiple pairs of wells, each pair has one well for high-pressure steam injection (injector), and one for the production of oil (producer).


The rendering of otherwise definable economic ore as unrecoverable.


Refers to the presence of a random variable. Stochastic modelling involves calculating probability distributions through random variation in inputs.

straddle plant

See NGL recovery (straddle plant).

strike area

An administrative geographical boundary used in relation to potential resource accumulations.

strip ratio

The amount of overburden that must be removed to gain access to a unit amount of coal. A stripping ratio may be expressed as (1) the thickness of overburden to the thickness of coal, (2) the volume of overburden to the volume coal, (3) the weight of overburden to the weight of coal, or (4) the cubic yards of overburden to tons of coal. Stripping ratios are commonly used to express the maximum thickness, volume, or weight of overburden that can be profitably removed to obtain a unit amount of coal.

successful wells drilled

Wells drilled for gas or oil that are cased and not abandoned at the time of drilling.


Sulphur is a chemical element commonly found in conventional natural gas, crude bitumen, crude oil, and coal.

surface loss

A sum of the fractions of recoverable gas that is removed as acid gas and liquid hydrocarbons, and gas that is used as lease or plant fuel or that is flared.

synthetic crude oil (SCO)

See crude oil (synthetic).



takeaway capacity

Takeaway capacity is the total capacity for moving crude oil out of Alberta, via pipeline, rail, and truck.


The initial reservoir temperature upon discovery at the reference elevation of a pool.

tight gas

Tight gas is gas trapped in the pores and fractures of low-permeability rocks. Producing tight gas requires extra stimulation, such as hydraulic fracturing.

tight hybrids

Tight hybrids are low-permeability oil or gas resources. They cannot be easily divided into “conventional” and “unconventional” resources by factors such as viscosity, degree of permeability, or recovery process.

This definition applies to “halo” deposits where the quality of the reservoir decreases with increasing distance from the conventional core and to mixed-lithology reservoirs containing both conventional and unconventional deposits.

tight oil

Tight oil is crude oil trapped in the pores and fractures of low-permeability rocks and is generally liquid under reservoir conditions. Producing tight oil requires extra stimulation, such as hydraulic fracturing.


ultimate potential

An estimate of the initial established reserves that will have been developed in an area by the time all exploratory and development activity has ceased, having regard for the geological prospects of that area and anticipated technology and economic conditions. Ultimate potential includes cumulative production, remaining established reserves, and future additions through extensions and revisions to existing pools and the discovery of new pools. For hydrocarbons, ultimate potential volumes can be determined by the following simple equation: ultimate potential = initial established reserves + additions to existing pools + future discoveries.

undeveloped reserves

Undeveloped reserves are reserves expected to be recovered from known accumulations where the cost required to begin production from an existing well is significant compared with the cost of drilling and completing an entirely new well. The costs required to begin production could include recompleting an existing well or installing production or transportation facilities. The reserves expected to be recovered must fully meet the requirements of the category indicating its probability of recovery (proved, probable, possible) and expected to be developed within a limited time.

In multiwell pools, it may be appropriate to allocate total pool reserves between the developed and undeveloped subclasses or to subdivide the developed reserves for the pool between developed producing and developed non-producing. This allocation should be based on the estimator’s assessment as to the reserves that are expected to be recovered from specific wells, facilities, and completion intervals in the pool and their respective development and production status.

unit train

Unit trains, or block trains, are freight trains in which all cars are carrying the same type of commodity, all bound for the same destination. In this way, unit cars do not need to stop at different junctions for each commodity and can make single, nonstop runs.

upgraded bitumen

A mixture of hydrocarbons, similar to crude oil, derived by upgrading bitumen from oil sands. Generally considered to be equivalent to synthetic crude oil (SCO) but can also include refined petroleum products.


A process that converts bitumen and heavy crude oil into a mixture of lighter hydrocarbons by removing carbon or adding hydrogen.




A hole drilled in the earth for the purpose of finding or producing natural gas or crude oil.

wells placed on production

Wells that have been physically connected to gathering infrastructure and are reporting production; includes newly drilled wells that have been placed on production and recompletions into new zones of existing wells.

working gas storage

The amount of natural gas that can be injected into the storage and withdrawn at a later moment in time to meet demand.

Western Canadian Select (WCS)

A grade of heavy crude oil derived from of a mix of heavy crude oil and crude bitumen blended with diluents. The price of WCS is often used as a representative price for Canadian heavy crude oils.

West Texas Intermediate (WTI)

A light sweet crude oil that is typically referenced for pricing at Cushing, Oklahoma.




Any stratum or sequence of strata that is designated by the AER as a zone (Oil and Gas Conservation Act, section 1(1)(ggg)).

Zone (gross)

The full interval of rock from top to base of a zone. Gross zone will include uneconomic intervals.

Zone (thief)

Water or gas zones within a steam-assisted gravity draining reservoir that steals heat or pressure from the steam injected into the reservoir. The more energy thief zones steal, the less there is remaining to heat the bitumen.

PSAC Areas

The Petroleum Services Association of Canada (PSAC) has sectioned Canada into a number of geographic regions based on the predominate type of geological interest to the oil and gas industry. Figure AA.1 shows the PSAC areas in Alberta. The AER often refers to the historical, current, and future oil and gas activity it discusses by PSAC area.


Conversion Factors