Abandonment (Abandoned) Well

A well that is shutdown permanently, since it has ceased to produce crude oil.  Abandoment of a well should involve set procedures, that may vary depending on the nature of the formation and on individual juristiction's regulations.  Abandonment usually involves cementing the well through important formations near surface, removing surface aparatus, and providing a cap on the wellhead.

Alida Beds

Named after Alida Oil field, the Alida Beds are located in southeast Saskatchewan, 225 km from Regina, and have been producing oil since their discovery in 1955.  The formation consists of two carbonate reservoirs that have a combined thickness of about 52 meters; the beds have been producing for over 40 years, and have had their lives extended with the advent of horizontal drilling technology.  


Anhydrite is an evaporite mineral that occurs in sedimentary basins and it is interbedded with halite, gypsum, and limestone; they occur in the geological record where large volumes of sea water have been evaporated.

Active Well

An active well is one that is currently in a process of producing oil or gas.

Acid Stimulation

Acid stimulation -- or acidizing, or reservoir stimulation -- is the treatment of a reservoir formation by injecting substances that act as an acid to remove near-well damaging substances in order to improved oil  or gas production.


The annulus is the space between the casing and tubing in a well, or between the wellbore and casing, that allows for fluid to flow and cirulate in the well. 

Appraisal Well

An appraisal well is drilled to measure and determine the size, and the volume, of hydrocarbons in a reservoir.

API Gravity

API (American Petroleum Institute) Gravity is used to measure the relative density of various petroleum fluids and how heavy or light they are.  A low API number (under 10) means the liquid is heavy, often with an inability to flow, and more likely to sink.  A higher API value (over 10) means the petroleum product is light and able to flow more easily.


An aquifer is a underground layer of permeable rock bearing water or other liquids. The term, in petroleum geology, can refer to any liquid-bearing zone in the subsurface.  In relation to the PTRC's Aquistore project, the saline aquifer into which the CO2 is being injected is a permeable sandstone and brine formation 3.4 km underground.  The opposite of an aquifer is an aquitard, which is a rock formation that is not permeable and does not contain or allow for the passage of liquids.  In the image included to the right of the Aquistore geology, the layers on the left are aquitards, and those broken out on the right are aquifers.


Bakken Formation

The Bakken Formation occupies about 200,000 sq miles (520,000 sq kilometres) of the subsurface in the Williston Bassin, which underlying parts of Montana, North Dakota, Saskatchewan and Manitoba.

Birdbear Formation

The Birdbear Formation lies on top of the Duperow Formation and beneath the Three Forks Formation in the central part of the Williston Basin. Oil and gas have been produced from the Birdbear Formation in Saskatchewan and Montana since the early 1960s.


A battery in the oil and gas industry refers to a storage facility / collection point for fluid production from a well or group of wells, which measures and separates the oil, gas and water produced from those wells prior to delivery of the oil or gas to the market.

Bubble Point

The bubble point is the pressure reading within a reservoir at which the first bubbles comes out of the petroleum fluid.  The bubble point is affected by pressure and temperature in the reservoir.


BOED is an acronym, meaning Barrel of Oil Equivalent per Day.  The term is often used when oil or gas companies are measuring their production in square metres or feet, and want to translate those amounts into barrels per day.


A naturally occurring semisolid organic matter in a reservoir containing hydrocarbons.  Bitument has a very low API gravity and usually requires upgrading to synthetic crude oil or the addition of a diluent (natural gas) to flow to market..



Coring is a term that refers to samples of rock taken from oil or gas wells for the purpose of examination to determine the characteristics of reservoir, and such features as permeability, porosity, etc. -- all of which will help determine what recovery processes are best for producing oil.  Here, core samples taken from different geological layers during the drilling of the Aquistore well are on display.

Cumulative Production

The total amount of hydrocarbons produced from a reservoir over a specific period of time.

Cyclic Steam Stimulation (also, Cyclic Steam Injection)

A thermal oil recovery method that injects steam into a reservoir.  This injection is then followed by a period of soaking where the well is shut in for several days.  The soaking period leads to a reduction in the oil viscosity, and the well is put back on production.


Carbonates are a class of sedimentary rock mainly composed of calcium carbonate minerals.

Conventional Crude Oil

Conventional crude is an oil that can be produced easily using traditional drilling methods via the natural pressures in existence in the reservoir.


Condensate is a high API gravity, low-density liquid hydrocarbon that is created in association with natural gas as pressure depletes.


The casing is steel pipe that is cemented into a wellbore to prevent the formation from collapsing or caving in.


CHOPS is an acronym that stands for cold heavy oil production with sand. It is a non-thermal method that was developed, along with cavity pump technology, in the 1980s to increase oil production from Saskatchewan and Alberta's heavy oil reservoirs.

Chemical Flooding

Chemical flooding is an enhanced oil recovery method that uses chemicals to reduce the surface tension between oil and water, allowing for more oil production than simple waterflooding.  It is an EOR process used after the primary and secondary recovery.


Completion refers to steps taken to convert a drilled well into a production well, and includes the steps of casing, cementing, perforation, and gravel packing.

Carbon Capture and Storage (CCS)

Carbon capture storage (CCS) is a suite of technologies that combine to capture CO2 (carbon dioxide) from the atmosphere or from a set point source like a coal-fired power station, compress and transport that CO2, and then inject it deep underground into porous rock formations (either a deep saline aquifer, or a depleted oil/gas field).  Visit the PTRC's Aquistore page for more information on the storage component of CCS.



Sedimentary rock composed of magnesium-rich carbonate mineral.

Dominion Land Survey System (DLS)

Historically, the Dominion Land Survey System was imposed in the late 19th and early 20th Centuries in Canada, and divides western Canada into one-square-mile sections for petroleum and agriculture purposes.  

Drilling Rig

A large structure with the equipment to drill an oil, gas or injection well.  Drilling rigs can be both onshore and offshore.  The photograph here shows the rig that was used to drill the Aquistore CO2 injection well in July of 2012.

Downstream Sector

Downstream oil and gas refers to the refining of crude oil, and the purifying the natural gas, including the marketing and distribution of products that are derived from both.  This the opposite to Upstream, which refers to the exploitation/production of oil and gas (drilling, recovery).

Directional Drilling (also, Horizontal Drilling)

Directional drilling in the oil and gas industry is drilling at an angle across the reservoir such that the well hits more targets across a the production zone, to improve the productivity of wells.

Dew Point

The dew point is the pressure point at which the first liquid comes out of solution in a gas condensate reservoir.


Exploratory Well

A deep test well that is drilled onshore and/or offshore to discover oil and gas reserves after collecting seismic data.

Enhanced Oil Recovery (EOR)

Also called Tertiary Recovery, EOR is a method to extract hydrocarbons through thermal or chemical techniques by altering the oil properties, and to improve oil displacement.


A dispersion of one liquid into another immiscible liquid that will not separate into individual components.


Emissions refer to gasses that are released into the air from power plants and factories.  These emissions may contain different gases, such as NOx and SOx, and are a particular focus of greenhouse gas mitigation efforts when they contain CO2 and methane.

Electromagnetic Imaging (EM)

This technology allows well operators to image the deep subsurface around their wells by dropping an electrode down the length of a well, settling at various points in the subsurface where an image needs to be created. EM surveys measure conductivity in the reservoir through electromagnetic induction – different conductivities correspond to different substances.  This technology has been used to find underground voids (spaces), oil and gas fields, and in the case of PTRC’s Aquistore Project, identify the CO2’s location in the Deadwood formation 3.2 km underground.


Fugitive Emission

Fugitive emissions refer to gases or vapors that leak from production facilities, wells/wellheads and pipelines.  They are irregular releases of gas that need to be eliminated through various mitigation technologies.

Frobisher Beds

The Frobisher beds and Frobisher oil field are located in southern Saskatchewan, and consist of oolitic and pisolitic carbonates, sandy dolomite and dolomitic limestone. The thickness varies from 43m to 70m.

Foamy Oil

In Saskatchewan and Alberta heavy oil fields, foamy oil is created when heavy oil is produced from reservoirs.  Gas that is in the heavy oil, as the oil becomes depressurized at the wellhead, begins to come out of the solution and those gas bubbles get dispersed in the oil solution, making it foam and become more viscous.  In effect, a heavy oil producer wants to induce foamy oil and keep the gas bubbles dispersed as long as possible as the reservoir begins to produce because the dispersion makes the oil flow more freely and increases recovery factors. 


A stimulation process designed to enhance oil and gas productivity. The process involves pumping fluid and sand into an oil or gas formation deep underground, along a horizontal well, and then introducing pressure or small charges that cause fractures within the reservoir.  Those fractures allow for the drainage of hydrocarbons into horizontal producing wells.

Fossil Fuel

Fossil fuels include oil, natural gas, and coal, which were created in the geological past from the remains of living organisms.

Fire Flooding (also, In Situ Combustion)

A oil recovery technique used to inject oxygen into the hydrocarbon formation, and then introducing combustion into the reservoir to lower the hydrocarbons' viscosity. A producing well then collects the heated production. 

Flare Gas (Flaring)

The burning of an unwanted gas at a production facility or well head, which would otherwise get released into the environment, from a petrochemical, oil/gas battery, or processing plant.


The geology and layers above, in and below a reservoir that need to be characterized prior to drilling a well. 

Fault Trap

The area in a geological formation where the hydrocarbon flow is restricted by a sealed rock.  Fault traps are often the geological formations (see image) that trap and seal hydrocarbons, and are often good oil production zones.


Gas-to-Oil Ratio

This ratio measures the volume of gas that comes out of solution to the volume of oil, at standard conditions.



A molecule made up of carbon and hydrogen atoms. Many of the fuels used on daily basis for transport and heating consist of hydrocarbons.

Heavy Crude Oil

A very viscous oil that is unable to flow to the production well under normal reservoir conditions.  Heavy oil recovery usually involves the addition of heat or solvent to lower the oil's viscosity.


Injection Well

A well where fluid  or gases are injected into a reservoir to maintain the reservoir pressure and to maintain an effective recovery factor.

Inactive Well

A well where production, injection, disposal or workover operations have been ceased, but permanent abandonment has not taken place.

Infill Wells

An infill well refers to the addition of a well(s) in a field to decrease the average well spacing, in order to increase the recovery in the reservoir by improving the continuity between injector and producer wells.  In simple terms, in fill wells (like the name suggests) increases the number of wells in a select area where wells already exist.

In Situ Combustion (see also, Fire Flooding")

The methods of thermal recovery where fire is generated into the reservoir by injecting oxygen. As a result, the heated and combusted part of the reservoir creates a front where the remaining hydrocarbons are pushed to the oil to the production well.

In Situ

In Situ is a Latin term meaning "in position" or "on site".  When used in relation to oil sands, "in situ oil sands extraction" means oil sands production that is done in place (e.g. through injection of steam or solvent deep underground and drawing the oil to surface without disturbing the sand).  Ths is the opposite of "mined oil sands", which require the sand to be moved from its location to processing facilities where hot water is introduced to strip off the oil.

Improved Oil Recovery

See Enhanced Oil Recovery.


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An agreement between a company or an individual with a mineral rights owner granting permission to that  company to search and produce possible hydrocarbons on the right holder's land.


Sedimentary rock mainly composed of calcite mineral.


Liquified Natural Gas.


Liquefied Petroleum Gas.

Light Crude Oil

A crude oil that has an API gravity of more than 40.



MMCF means Millions of Cubic Feet.  This is a standard unit of measurement used in the United States for oil and gas production.

Manville Group

The Manville Group consists of interbedded nonmarine sands and shales in the border region between Alberta and Saskatchewan. The thickness of the Manville Group is about 145 meters and is found through the Vermilion area of Alberta, and has been accessed in the Athabasca, Edmonton, and Lloydminster areas.


A subsystem in the geological timescale, the Mississippian is the lowermost of the two geological subperiods in the Carboniferous period. It is named after the Mississippi River Valley.

Midale Beds

The Midale Beds took its name from the Midale oil field in southeastern Saskatchewan. The thickness of the Midale Beds varies from 15m to 45m.  It is a major oil producing formation in Saskatchewan.

Midstream Oil and Gas

One of the three major stages of oil and gas industry operations which includes the processing, sorting, transporting and marketing of oil and gas.  See also Upstream and Downstream Oil and Gas.

Microbial Injection

An enhanced oil recovery process in which microorganisms are used in a reservoir to improve oil recovery by injecting the microbes into the reservoir, or just by enhancing the population of microbial activity already in the reservoir by injecting nutrients.


MMBL means million of barrels of oil.  For example, 20 MMBL means 20 million barrels of oil.


MBOE means Thousands of Barrels of Oil Equivalent.


MCF means Thousands of Cubic Feet.  It is a standard measurement used in the United States for natural gas production.  Other countries use metres, not feet.

Medium Crude Oil

Oil with an API gravity in between 31-33.


MBBL means thousands of barrels.  For example, 20 MBBL oil means 20,000 barrels of oil.


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A Colorless toxic gas formed from oxygen by an electrical discharge.

Oil Sands

A porous rock layer considered to be a mixture of sand, clay, water and bitumen.  Both Alberta and Saskatchwan have oil sands deposits, but only Alberta's are recoverable using existing extraction technologies.  Signficiant oil sands deposits also exist in locations such as Utah in the United States, and in Venezuela and Colombia in South America.

Oil-in-Place (OIP)

Oil-in-place refers to the volume of oil in a reservoir prior to the beginning of production.  The term is different than "reserves" in a reservoir in that oil-in-place includes recoverable and non-recoverable oil, whereas "reserves" refers only to the recoverable oil in a reservoir.  As an example, the Alberta oil sands have 2 trillion barrels of oil-in-place, but only 175 billion barrels of those are considered recoverable "reserves".


Produced Water

The water that comes to the surface and is produced as a by-product of oil production from a reservoir.

Primary Recovery

The first stage of oil and gas recovery where oil and gas extraction relies on the natural pressures in the reservoir to produce oil and/or gas.


A solid material that is used to keep an induced fracture open in a reservoir, such as sand and/or ceramics.

Poplar Beds

These beds are named after the Poplar Beds located in Montana, and have produced oil from several relatively thin carbonate layers. The beds cover about 12950 km2 in southeastern and south-central Saskatchewan, with average bed thickness in Saskatchewan of about 117m.


Potash is found in the vast majority of Saskatchewan, which has the world’s largest reserves of this fertilizing mineral. It is most often found approximately 1000 meters below the earth's surface. It is mined in two ways: (1) either indirectly through the injection of water to dissolve the potash and bring it to surface, or (2) physically through mining using tools and direct man power.  See also Prairie Evaporite.

Prairie Evaporite

A geological formation across much of Western Canada and the states of Montana and North Dakota.  In Saskatchewan, it covers most of the south and central of the province. It consists of halite, carnallite, and sylvite of various hues and degrees of crystallinity. The maximum thickness of the formation is 218m.  The Prairie Evaporite is a main souce of Potash for the province of Saskatchewan.

Possible Reserves

An estimate number of hydrocarbons that maybe be available for extraction in a oil bearing formation/reservoir, using existing equipment, and under existing conditions.


A measurement of the void space in a rock. See also the description of Permeability for an understanding of how porosity differs from it.


Naturally occurring hydrocarbon compounds found in rock

Pay Zone

The portion in a reservoir that contains an economically producible hydrocarbon.


The ability of a rock to transmit fluid, which is measured in Darcie’s or millidarcies.  A rock may be porous (filled with microscopic pores and holes) but have no permeability (connections between those pores that allow for the flow of liquid).  When an oil field lacks permeability it is sometimes referred to as a "tight' oil reservoir that requires some level of fracking to produce.


A hole in a casing or a liner that is created through the use of a perforation gun (hole producing gun) that allows oil and gas to flow into a production well and eventually get produced at surface.

Polymer Flooding

An enhanced oil recovery technique that introduces viscous water into the oil, through a soluble polymer (large molecules created from monomers) that helps create a miscible solution, which allows oil to flow more freely to production wells.


A pumpjack is used in the oil and gas industry to extract crude oil through artificial lift, which creates pressure in the wellbore to draw the oil to the surface.


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Red River Formation

The Red River formation extends throughout the Manitoba outcrop belt. The formation consists of a basal fossiliferous, mottled dolomitic limestone overlain by a cherty dolomite. In the southern end the belt formation is about 150m, and thins to less than 50m towards the north. At the central part of Williston Basin it reaches up to 215m.

Ratcliffe Beds

The Ratcliffe Beds are located in Southern, and south-central Saskatchewan. The average thickness is about 46m, and further south it goes up to 80m.  This is a major oil producing zone in the province.

Reservoir Stimulation

A process or number of processes that are used to repair formation damage or improve reservoir productivity. This includes processes such as hydraulic fracturing and matrix acidizing.


An estimate of how much oil can ultimately be recovered for the oil-in-place within a reservoir.

Recovery Factor

The percentage of oil recovered from a reservoir. It is usually calculated by dividing the total oil production by the total oil reserves.


Sweet Gas

A natural gas that does not contain hydrogen sulfide. Sweet gas in a pure form can be used with little refining.


A branch of geology concerned with the study of rock layers; the term is also used to refer to the layers of rock themselves.

Shaunavon Formation

The Shaunavon is located in south-western Saskatchewan; in the Williston Basin it appears in Montana and North Dakota. The formation thickness is about 48 meters.  

Souris Valley Beds

These beds lie below the Tilston Beds in the Souris Valley (southwestern Saskatchewan) and are comprised of a dark grey, sparsely fossiliferous, thin bedded basin-type sequence of argillaceous limestones, calcareous shales, and chert. Souris Valley has not produced any oil and gas due to not containing any positive topographic features.

Suspended Well

A well in which operations have been discontinued for an indefinite period.

Steam Flooding

Also referred to as Steam Injection. This is a process in which steam is injected into a reservoir, increasing the temperature of crude and reducing its viscosity. The process also creates a sweeping efficiency and pushes the oil towards the production well.

Secondary Recovery

The process of injecting a fluid to maintain reservoir pressure is called secondary recovery. The most common techniques are gas injection or water flooding.

Shale Oil

A crude oil that lies between  layers of shale rock. Shale is a fine-grained sedimentary rock with very low permeability. This oil can be recovered through the process of fracking.

Solution Gas

A natural gas which is dissolved in the reservoir along with crude oil.

Sour Gas

Any gas that contains hydrogen sulfide (H2S).

Steam-Assisted Gravity Drainage (SAGD)

A process that involves two horizontal wells parallel to each other. The top well injects steam which lowers the oil viscosity such that is flows to the lower production well.


Tilston Beds

Named after Tilston oil field near Tilston, Manitoba. The thickness varies from 49m to 80m. It is divided into two portions MC1 and MC2, MC1 consist on of oolitic-pisolitic, and grinodial grey stone. MC2 consist on argillaceous limestone or dolomitic limestone.

Tight Oil

When light oil is present in low permeability formations such as shale or tight sandstone, it is referred to as "tight oil". This oil is usually recovered through fracking.

Thermal Recovery

A process where heat is introduced into a reservoir. This process reduces the viscosity and increases the mobility of the oil, which improves recovery.

Tertiary Recovery (see also Enhanced Oil Recovery)

Another term for enhanced oil recovery. Tertiary recovery involves the extraction of oil that is not accessible from the natural energy/pressure of the reservoir. This extraction is usually performed by injecting a fluid.



One of three operational stages in oil and gas (see also midstream and downstream). Upstream includes all the processes in the exploration and production of oil and gas (drilling, extraction, etc.).

Underbalanced Drilling

A process of drilling oil and gas wells in which the wellbore pressure is kept lower than the static pressure as the well is drilled.

Unconventional Oil and Gas

This term refers to resources that cannot be explored and produced by conventional means. Examples of unconventional oil include oil sands, tight oil and shale oil. These use unconventional processes like fracking and SAGD.



Viscosity is a measure of a fluid's consistency and deformation. i.e. honey has a higher viscosity (thickness) than water.

Vapex (also, solvent vapour extraction)

A non-thermal heavy oil recovery method (Vapex is the commercial term for Solvent Vapour Extraction). Two horizontal wells are placed at a certain distance on top of each other. A solvent vapor is injected through the top well and that solvent reduces the oil viscosity. Oil is then produced through the bottom well.


Williston Basin

A large sedimentary basin rich in petroleum and potash that runs beneath eastern Montana, western North and South Dakota and southern Saskatchewan.  The image here shows both the Williston Basin and the Bakken Formation overlying it.

Western Canada Sedimentary Basin

A sedimentary basin underlying 1,400,000 kilometer of western Canada, including southwestern Manitoba, Saskatchewan, Alberta, and northeastern British Columbia, as well as the southwest corner of the Northwest Territories.  The formation contains various kinds of sedimentary rock that may include hydrocarbons.

Waterous Formation

A stratigraphical unit formed in the Triassic to Jurassic ages located in the western Canadian Sedimentary Basin.

Wet Gas

Any gas with a small amount of liquid present (usually water).


A hole that is drilled for exploration and recovery of natural resources from underground. It can be encased with materials such as cement and steel.


Waterflooding is a process where water is injected into an oil field such that the water pushes the oil to a producer well, increasing the recovery factor.

Well Logs

A well log provides measurement of particular physical properties versus the depth of a drilled hole.

Well Integrity

Well integrity is attained when a well has been drilled and maintained properly, with the application of technical, operational, and organizational solutions to reduce any risk of uncontrolled release of formation fluids throughout its life cycle.  Integrity is maintained through monitoring of the surface, including soil and ground water around the well, and by properly enclosing the well, usually through proper cementing and abandonment procedures, after its productive life is over.


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