Abstract

The Basins of the Central Cordilleran Region of British Columbia and Yukon are the deeper and better preserved portions of a Permo-Carboniferous and Mesozoic Geosyncline that stretches from central Yukon to southern British Columbia. This Geosyncline is a broad, northwest trending linear trough bounded on the west by the Coast Geanticline and on the east by the Omineca and Pinchi Geanticlines.

The Basins are difficult to outline and the outline positions used herein should be considered optimistic. The Whitehorse Basin is at the northern end of the Geosyncline in the Yukon and is isolated to the south by the Atlin Horst and the Stikine Arch. The Bowser Basin in north-central British Columbia is bounded by the Stikine Arch on the north and Skeena Arch on the south. The Tyaughton and Nechako Basins in south-central British Columbia are bounded by the Skeena Arch on the north and the Yalakom and Fraser fault systems on the south.

The Basins contain from 15,000 to 40,000 feet of sediments and have been subjected to extensive deformation and volcanism. A general lack of observed porosity in the rocks, in outcrop and in the three welts drilled by oil companies, is an adverse factor for the accumulation of petroleum. Permian and Upper Triassic fractured carbonates likely represent the main reservoir potential in this region but Jurassic and Cretaceous clastics are possible reservoirs in certain areas.

Geochemical and petrographic analysis of the rocks throughout the area indicate thermal metamorphism with maximum regional paleo-temperatures between 425° and 500°F. The organic material is in a black kerogen or graphitic state indicating that dry gas (methane) is likely to be the main hydrocarbon present.

Estimates of the potential gas reserves contained within these Basins are between 9.9 and 44.6 trillion cubic feet of natural gas with 24.8 trillion cubic feet considered the most probable.