Leduc Formation

Leduc Formation Stratigraphic range: Frasnian PreЄ Є O S D C P T J K Pg N
Type	Geological formation
Underlies	Duvernay Formation, Ireton Formation
Overlies	Beaverhill Lake Formation
Thickness	up to 300 metres (980 ft)^[1]
Lithology
Primary	Dolostone
Other	Limestone
Location
Coordinates	53°20′42″N 113°41′42″W / 53.3451°N 113.6949°W / 53.3451; -113.6949Coordinates: 53°20′42″N 113°41′42″W / 53.3451°N 113.6949°W / 53.3451; -113.6949
Region	Alberta
Country	Canada
Type section
Named for	City of Leduc, Alberta
Named by	Imperial Oil Limited, 1950^[2]

The Leduc Formation is a stratigraphic unit of Late Devonian (Frasnian) age in the Western Canada Sedimentary Basin.^[3] It takes its name from the city of Leduc, and it was formally described from the B.A. Pyrz No. 1 well in central Alberta, between the depths of 1,623.7 m (5,327 ft) and 1,807.5 m (5,930 ft), by Imperial Oil Limited in 1950. Supplementary information came from a complete section of the formation that was cored in Imperial Oil's Leduc No. 530 well between 1,633 m (5,358 ft) and 1,863 m (6,112 ft).^[1]^[2]^[4]

The Leduc Formation is a major producer of oil and gas in central Alberta, and the drilling of the highly successful Leduc No. 1 well in 1947 ushered in a new era in the Western Canadian petroleum industry.^[5]

Lithology

The Leduc Formation consists of fossil reefs that are highly porous, which makes them excellent reservoirs for oil and gas. They were deposited as limestone and mudstone in shallow water reef environments. Stromatoporoids were the primary reef-building organisms, and rock-types range from skeletal mudstones and floatstones to finer grained muddy packstones and wackestones. Many, but not all, of the reefs were later subjected to dolomitization during diagenesis, which increased their porosity, and they now consist of dolostone rather than limestone.^[4]

Oil and gas production

The Leduc No. 1 well.

The Leduc Formation is a major producer of oil and gas in central Alberta. The Leduc No. 1 well which was drilled in 1947 produced 50 thousand cubic metres (more than 300 thousand barrels) of oil^[5] and marked the beginning of the post-war Albertan oil boom. The Strachan and Ricinus West gas fields, discovered in 1967 and 1969, also produce from Late Devonian Leduc-age reefs.^[6]

Distribution and thickness

Leduc Formation occurs as discrete, discontinuous reef "buildups" in a line following the Woodbend shelf margin from Drumheller in central Alberta to the Peace River Arch area in northern Alberta. The formation is absent in inter-reef areas, and buildups can reach from 180 meters (590 ft) to 300 meters (980 ft) in thickness.^[4]

Relationship to other units

In central Alberta the Leduc Formation conformably overlies the platform limestones and dolostones of the Cooking Lake and Beaverhill Lake Formations. In northern Alberta near the Peace River Arch it rests on older red beds or on the Granite Wash. The Leduc reefs are surrounded by shales of the Duvernay and Ireton Formations and the Woodbend Group that were deposited in non-reefal, open marine environments.

The Leduc reefs are the same ages as, but not contiguous with, the reefs of the Cairn Formation which are located farther west. Because the Leduc reefs are nowhere exposed at surface, the extensive outcrops of the Cairn reefs in the Canadian Rockies have been studied to increase the understanding of the Leduc reefs.^[7]

References

1 2 Lexicon of Canadian Geological Units. "Leduc Formation". Retrieved 2009-02-09.
1 2 Imperial Oil Limited, Geological Staff, Western Division, 1950. Devonian nomenclature in the Edmonton area, Alberta, Canada. Bulletin of the American Association of Petroleum Geologists, vol. 34, p. 1807-1825.
↑ Mossop, G.D. and Shetsen, I., (compilers), Canadian Society of Petroleum Geologists and Alberta Geological Survey (1994). "The Geological Atlas of the Western Canada Sedimentary Basin, Chapter 12: Devonian Woodbend-Winterburn strata of the Western Canada Sedimentary Basin". Retrieved 2014-10-17.
1 2 3 Glass, D.J. (editor) 1997. Lexicon of Canadian Stratigraphy, vol. 4, Western Canada including eastern British Columbia, Alberta, Saskatchewan and southern Manitoba. Canadian Society of Petroleum Geologists, Calgary, 1423 p. on CD-ROM. ISBN 0-920230-23-7.
1 2 Heritage Community Foundation. Alberta's Petroleum Heritage
↑ Hriskevich, M.E., Faber, J.M., and Langton, J.R., 1980, Strachan and Ricinus West Gas Fields, Alberta, Canada, in Giant Oil and Gas Fields of the Decade: 1968-1978, AAPG Memoir 30, Halbouty, M.T., Tulsa: American Association of Petroleum Geologists, ISBN 0891813063, p. 315
↑ Bloy, G.R., Hunter, I.G. and Leggett, S.R. 1984. Depositional environments of the Devonian Cairn Formation, Rocky Mountain front ranges, Canmore, Alberta. Carbonates in subsurface and outcrop: 1984 CSPG Core Conference, Canadian Society of Petroleum Geologists, p. 148.

Western Canadian Sedimentary Basin

Hydrocarbon history	Oil sands and heavy oil Frontier exploration and development Natural gas liquids Natural gas

Depositional Regions	Southern Alberta Central Alberta Northwestern Alberta Plains South-central Canadian Rockies foothills North-east Plains North-central foothills Liard River Fort Nelson Northern Rocky Mountains Fort St. John Saskatchewan Western Manitoba

Northwest Plains	Paskapoo FM Scollard FM Wapiti GRP Smoky GRP Puskwaskau FM Badheart FM Muskiki FM Cardium FM Kaskapau FM Pouce Coupe MBR Doe Creek MBR Dunvegan FM Fort St. John GRP Shaftesbury FM Peace River FM Spirit River FM Bullhead GRP Bluesky FM Gething FM Cadomin FM Nikanassin FM Fernie GRP Rock Creek MBR Poker Chip Shale Nordegg MBR Schooler Creek GRP Baldonnel FM Charlie Lake FM Halfway FM Doig FM Montney FM Belloy FM Stoddart GRP Taylor Flat FM Kiskatinaw FM Golata FM Rundle GRP Debolt FM Shunda FM Pekisko FM Banff FM Exshaw FM Wabamun FM Trout River FM Kakisa FM Redknife FM Jean Marie MBR Woodbend GRP Irteton FM Fort Simpson FM Leduc FM Duvernay FM Cooking Lake FM Beaverhill Lake GRP Waterways FM Swan Hills FM Fort Vermilion FM Elk Point GRP Watt Mountain FM Gillwood MBR Presqu’ile FM Sulphur Point FM Pine Point FM Muskeg FM Zama MBR Black Shale Keg River FM Rainbow MBR Chinchaga FM Cold Lake FM Ernestina FM Basal Red Beds Granite Wash Canadian Shield

Southern Alberta Plains	Cypress Hills FM Porcupine Hills FM Ravenscrag FM Edmonton GRP Belly River GRP Oldman FM Foremost FM Pakowki FM Milk River FM Colorado GRP Mannville GRP Ellis GRP Swift FM Rierdon FM Sawtooth FM Rundle GRP Banff FM Exshaw FM Bakken FM Wabamun FM Crowfoot FM Nisku FM Ireton FM Leduc FM Cooking Lake FM Beaverhill Lake GRP Elk Point GRP Canadian Shield

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