Clearwater Formation | |
---|---|
Stratigraphic range: | |
Type | Geological formation |
Unit of | Mannville Group |
Sub-units | Wabiskaw Member |
Underlies | Grand Rapids Formation |
Overlies | McMurray Formation |
Thickness | up to 85 metres (280 ft) [1] |
Lithology | |
Primary | Shale |
Other | Sandstone, siltstone |
Location | |
Coordinates | 58°00′49″N111°20′38″W / 58.01365°N 111.34377°W |
Region | northeastern and central Alberta |
Country | Canada |
Type section | |
Named for | Clearwater River |
Named by | R.G. McConnell, 1893 |
The Clearwater Formation is a stratigraphic unit of Early Cretaceous (Albian) age in the Western Canada Sedimentary Basin in northeastern Alberta, Canada. [2] It was first defined by R.G. McConnell in 1893 and takes its name from the Clearwater River near Fort McMurray. [3]
Impermeable marine shales in the Clearwater Formation provided part of the trapping mechanism for the underlying Athabasca oil sands in the McMurray Formation. Sandstone units in the Clearwater Formation, including the Wabiskaw Member, can contain oilsand and heavy oil resources. [1]
Nearly complete specimens of plesiosaurs and ichthyosaurs, as well as one ankylosaur, have been recovered from the formation during oilsand mining. [4]
The Clearwater Formation consists of primarily of black and green shale, with some interbedded grey and green sandstone and siltstone, and ironstone concretions. To the southeast of Cold Lake it includes massive hydrocarbon-bearing, glauconitic salt-and-pepper sandstones with interbedded shales. [1]
The Wabiskaw Member forms the base of the Clearwater Formation. It consists of glauconitic sandstones with interbeds of black fissile shale, and it includes oilsand and heavy oil in some areas. [1] It was defined in well Barnsdall West Wabiskaw No. 1 (located between Wabasca River and Lesser Slave Lake in central Alberta) by P.C. Badgley in 1952. [5]
The Clearwater Formation is present in the subsurface of northeastern and central Alberta, and is exposed on lower course of the Athabasca River, as well as along the Christina River, a tributary of the Clearwater River southeast of Fort McMurray. It reaches a maximum thickness of 85 metres (280 ft) on the Athabasca River, thins out to 6 metres (20 ft) in the Cold Lake area, and wedges out towards the south. It is not present south of Edmonton. [1]
The Clearwater Formation is part of the Mannville Group. It is conformably overlain by the Grand Rapids Formation and conformably overlies the McMurray Formation. It is equivalent to the Bluesky Formation and the lower Spirit River Formation in the Peace River region, and may be equivalent to the Cummings Member in the Lloydminster region. [1]
The Clearwater Formation was deposited in marine, near-shore and estuarine environments on the eastern side of the Western Interior Seaway, and it contains marine and, rarely, terrestrial fossils. Workers at mines near Fort McMurray have made a number of significant finds while removing Clearwater strata to expose underlying oilsand deposits. Plesiosaurs such as Nichollssaura and ichthyosaurs such as Athabascasaurus , some of them nearly complete, have been recovered at Syncrude Canada Ltd.'s mines. [4] [6] A well-preserved specimen of the nodosaurid Borealopelta markmitchelli has been recovered at the Suncor Millennium Mine. Plesiosaurs and ichthyosaurs were large marine reptiles, but the ankylosaur was an armoured dinosaur and represents a terrestrial animal that became entombed in the sea floor approximately 200 kilometres (120 mi) from the nearest known paleo-shoreline. Its bloated carcass probably washed out to sea and floated for several days before sinking to the sea floor. [4]
All of the specimens now reside at the Royal Tyrrell Museum of Palaeontology. [4]
The formation contains oilsand in the Cold Lake and Primrose Lake region. Heavy oil is produced from the loose sandstones of the Wabiskaw Member by means of horizontal drilling in the Wabasca oil field, and the Wabiskaw contains surface-mineable oilsand in the Fort McMurray area.
The oilsands of the Clearwater Formation are more difficult to tap than those of the McMurray Formation. Cenovus Inc.'s Tucker thermal oilsands project which opened in 2006 began to post a modest return in 2013. [7] Cenovus Inc. (CVE), with its head office in Calgary, Alberta, Canada is an integrated oil and natural gas producer.
Canadian Natural Resources use "employs cyclic steam or "huff and puff" technology to develop bitumen resources. This technology requires one well bore and the production consists of the injection and production phases. First steam is "injected for several weeks, mobilizing cold bitumen". Then the flow "on the injection well is reversed producing oil through the same injection well bore. The injection and production phases together comprise one cycle. "Steam is re-injected to begin a new cycle when oil production rates fall below a critical threshold due to the cooling of the reservoir." [8]
"Roughly 35 per cent of all in situ production in the Alberta oil sands uses a technique called High Pressure Cyclic Steam Stimulation (HPCSS), which cycles between two phases: first, steam is injected into an underground oilsands deposit to soften the bitumen; then, the resulting hot mixture of bitumen and steam (called a "bitumen emulsion") is pumped up to the surface. The process is then repeated multiple times." [9] An Alberta Energy Regulator (AER) news release explained the difference between high pressure cyclic steam stimulation (HPCSS) and steam assisted gravity drainage (SAGD). "HPCSS has been used in oil recovery in Alberta for more than 30 years. The method involves injecting high-pressure steam into a reservoir over a prolonged period of time. As heat softens the bitumen and water dilutes and separates the bitumen from the sand, the pressure creates cracks and openings through which the bitumen can flow back into the steam-injector wells. HPCSS differs from steam assisted gravity drainage (SAGD) operations where steam is injected at lower pressures without fracturing the reservoir and uses gravity drainage as the primary recovery mechanism." [10] Canadian Natural Resources Limited's (CNRL) Primrose and Wolf Lake in situ oil sands project near Cold Lake, Alberta in the Clearwater Formation, operated by CNRL subsidiary Horizon Oil Sands, use the high pressure cyclic steam stimulation (HPCSS).( AER 2013 )
Oil sands, tar sands, crude bitumen, or bituminous sands, are a type of unconventional petroleum deposit. Oil sands are either loose sands or partially consolidated sandstone containing a naturally occurring mixture of sand, clay, and water, soaked with bitumen, a dense and extremely viscous form of petroleum.
The Athabasca oil sands, also known as the Athabasca tar sands, are large deposits of bitumen or extremely heavy crude oil that constitute unconventional resources, located in northeastern Alberta, Canada – roughly centred on the boomtown of Fort McMurray. These oil sands, hosted primarily in the McMurray Formation, consist of a mixture of crude bitumen, silica sand, clay minerals, and water. The Athabasca deposit is the largest known reservoir of crude bitumen in the world and the largest of three major oil sands deposits in Alberta, along with the nearby Peace River and Cold Lake deposits.
Syncrude Canada Ltd. is one of the world's largest producers of synthetic crude oil from oil sands and the largest single source producer in Canada. It is located just outside Fort McMurray in the Athabasca Oil Sands, and has a nameplate capacity of 350,000 barrels per day (56,000 m3/d) of oil, equivalent to about 13% of Canada's consumption. It has approximately 5.1 billion barrels (810,000,000 m3) of proven and probable reserves situated on 8 leases over 3 contiguous sites. Including fully realized prospective reserves, current production capacity could be sustained for well over 90 years.
Steam-assisted gravity drainage is an enhanced oil recovery technology for producing heavy crude oil and bitumen. It is an advanced form of steam stimulation in which a pair of horizontal wells is drilled into the oil reservoir, one a few metres above the other. High pressure steam is continuously injected into the upper wellbore to heat the oil and reduce its viscosity, causing the heated oil to drain into the lower wellbore, where it is pumped out. Dr. Roger Butler, engineer at Imperial Oil from 1955 to 1982, invented the steam assisted gravity drainage (SAGD) process in the 1970s. Butler "developed the concept of using horizontal pairs of wells and injected steam to develop certain deposits of bitumen considered too deep for mining". In 1983 Butler became director of technical programs for the Alberta Oil Sands Technology and Research Authority (AOSTRA), a crown corporation created by Alberta Premier Lougheed to promote new technologies for oil sands and heavy crude oil production. AOSTRA quickly supported SAGD as a promising innovation in oil sands extraction technology.
Wabasca is an oil field in a remote area of northern Alberta, Canada. It is the fourth largest deposit of oil sands located in Alberta, located southwest of the larger Athabasca oil sands deposit. It is also known as the Pelican Lake Oilfield.
Canada's oil sands and heavy oil resources are among the world's great petroleum deposits. They include the vast oil sands of northern Alberta, and the heavy oil reservoirs that surround the small city of Lloydminster, which sits on the border between Alberta and Saskatchewan. The extent of these resources is well known, but better technologies to produce oil from them are still being developed.
Steam injection is an increasingly common method of extracting heavy crude oil. Used commercially since the 1960s, it is considered an enhanced oil recovery (EOR) method and is the main type of thermal stimulation of oil reservoirs. There are several different forms of the technology, with the two main ones being Cyclic Steam Stimulation and Steam Flooding. Both are most commonly applied to oil reservoirs, which are relatively shallow and which contain crude oils which are very viscous at the temperature of the native underground formation. Steam injection is widely used in the San Joaquin Valley of California (US), the Lake Maracaibo area of Venezuela, and the oil sands of northern Alberta,Canada.
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The Bluesky Formation is a stratigraphic unit of Lower Cretaceous age in the Western Canada Sedimentary Basin. It takes the name from the hamlet of Bluesky, and was first described in Shell's Bluesky No. 1 well by Badgley in 1952.
The McMurray Formation is a stratigraphic unit of Early Cretaceous age of the Western Canada Sedimentary Basin in northeastern Alberta. It takes the name from Fort McMurray and was first described from outcrops along the banks of the Athabasca River 5 kilometres (3.1 mi) north of Fort McMurray by F.H. McLearn in 1917. It is a well-studied example of fluvial to estuarine sedimentation, and it is economically important because it hosts most of the vast bitumen resources of the Athabasca Oil Sands region.
The Mannville Group is a stratigraphical unit of Cretaceous age in the Western Canadian Sedimentary Basin.
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