Montney Formation

Montney Formation Stratigraphic range: Anisian PreЄ Є O S D C P T J K Pg N
Type	Geological formation
Underlies	Doig Formation, Fernie Group
Overlies	Belloy Formation
Area	127,000 acres (510 km2)[1]
Thickness	up to 280 metres (920 ft)[2]
Lithology
Primary	Siltstone and shale
Other	Dolomitic siltstone, sandstone
Location
Coordinates	56°34′18″N 121°13′19″W / 56.57159°N 121.2219°W / 56.57159; -121.2219 (Buick Creek No. 7 well)Coordinates: 56°34′18″N 121°13′19″W / 56.57159°N 121.2219°W / 56.57159; -121.2219 (Buick Creek No. 7 well)
Region	British Columbia, Alberta
Country	Canada
Type section
Named for	Montney, British Columbia
Named by	J.H. Armitage, 1962

The Montney Formation is a stratigraphical unit of Lower Triassic age in the Western Canadian Sedimentary Basin in British Columbia and Alberta.

It takes the name from the hamlet of Montney and was first described in Texaco's Buick Creek No. 7 well by J.H. Armitage in 1962.^[3] The well was drilled 41 kilometers (25 mi) north of Fort St. John, immediately east of the Alaska Highway.

Lithology

The formation is composed of siltstone and dark grey shale, with dolomitic siltstone in the base and fine grained sandstone towards the top.^[2] The facies is shaley in the north and west of the extent (Fort St. John), silty in the center (Dawson Creek and Pouce Coupe areas) and becomes coarser (sandy) in western Alberta (Valleyview area).^[4]

Oil and gas production

Gas is produced from the Montney Formation in the Peace River Country in British Columbia, by Petronas among others,^[1] and Alberta, and oil is produced from the formation in northern Alberta.^[4] Horizontal drilling and extensive fracturing process is necessary to have the fluid flow through the low permeability siltstone. Shale gas extraction emerged in the late 2000s in the distal facies of the formation's western extent.

Distribution

The Montney Formation reaches maximum thickness in the foothills of the northern Canadian Rockies at 280 meters (920 ft), and thins out towards the north up to the Fort Nelson area and towards the east to Peace River.

Relationship to other units

Montney Formation is unconformably overlain by Jurassic or Cretaceous beds such as the Doig Formation or Fernie Group and unconformably underlain by the Permian or Carboniferous strata such as the Belloy Formation.

References