| Horn River Formation Stratigraphic range: Middle to Late Devonian |
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Drill cuttings sample seen through microscope |
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| Type | Geological formation |
| Sub-units | Muskwa Member, Otter Park Member, Evie Member |
| Underlies | Fort Simpson Formation |
| Overlies | Pine Point Formation |
| Thickness | up to 320 metres (1,050 ft)[1] |
| Lithology | |
| Primary | Shale |
| Other | Limestone |
| Location | |
| Named for | Horn River |
| Named by | Whittaker, 1922 |
| Region | British Columbia, Northwest Territories |
| Country | Canada |
The Horn River Formation (also Horn River Shale) is a stratigraphical unit of Devonian age in the Western Canadian Sedimentary Basin.
It takes the name from the Horn River, a tributary of the Mackenzie River, and was first described in outrop on the banks of Horn River in the Northwest Territories (at the time District of Mackenzie) by Whittaker in 1922.[2] It was redefined in 1963 in the sub-surface of the Fort Nelson area (well Fort Nelson a-95-J/94-J-10) by F.F. Gray and J.R. Kassube.[3]
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The Horn River Formation is composed of argillaceous bitumenous limestone, and dark siliceous and calcareous shale. [1]
Shale gas is produced from the siliceous shale of the Horn River Formation in north-eastern British Columbia, in the Greater Sierra field, north of Fort Nelson. Horizontal drilling and fracturing techniques are used to extract the gas from the low permeability shales.[4] The original-gas-in-place volumes are estimated to be up to 500 Tcf [5], making it the third largest North American natural gas accumulation discovered prior to 2010[6]. Companies involved in the extraction of natural gas from the Horn River Shale include EnCana, Apache, EOG, Stone Mountain Resources, Exxon, Quicksilver Resources, Nexen and Devon Energy.
The Horn River Formation occurs in north-eastern British Columbia and extends to Great Slave Lake in the Northwest Territories, where it outcrops. It reaches a maximum thickness of 320 metres (1,050 ft) in the sub-surface of the Fort Nelson area.[1]
The Horn River Formation is overlain by the Fort Simpson Formation and underlain by the limestones of the Lonely Bay Formation, Nahanni Formation or Pine Point Formation.[1]
It is equivalent to the Slave Point Formation. It includes the Muskwa Formation, and the Waterways Member of the Hay River Formation in the Northwest Territories. It includes the pinnacle reefs of the Horn Plateau Formation.
The Horn River Shale was divided into the following members, from top to base:
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