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The AAPG/Datapages Combined Publications Database

CSPG Special Publications


Facts and Principles of World Petroleum Occurrence — Memoir 6, 1980
Pages 983-983
Symposium Abstracts

Exploration and Development: Sukunka-Bullmoose Gas Field, British Columbia: Abstract

D. L. Barss1, Francois Montandon2

Two commercial gas accumulations have been confirmed at Sukunka and Bullmoose in the Rocky Mountain Foothills of British Columbia, 103 km (64 miles) southwest of the city of Dawson Creek. The gas is trapped in complex anticlines involving low-grade carbonate reservoirs of Triassic age. In addition, three separate discoveries, two in Triassic carbonates and one in Cretaceous sandstones, have been made in the general area. Proven and probable reserves of sour gas are estimated at 3.32 × 109m3 (1.18 tcf). Sales gas is estimated to be in the order of 16.6 × 109m3 (590 bcf).

The sequence of events leading to the pooling of Triassic gas are as follows:

  • The gas is believed to have had its origin in the Upper Triassic. The relatively high H2S and CO2 content suggest an association with the anhydrites present in the underlying Charlie Lake Formation.

  • Following minor erosion, the Triassic reservoir and source rocks were sealed by deeper water muds of the Jurassic Fernie Formation and were covered by a 3 660+ m (12 000+ ft) Cretaceous clastic sequence.

  • Throughout the burial history, short distance migration of the hydrocarbons into locally permeable and porous carbonates and segregation in very low porosity, non-permeable sediments of the Upper Triassic occurred.

  • The last significant event leading to the accumulation of gas in Triassic rocks was folding, faulting and fracturing of the more competent Pardonet/Baldonnel carbonates during the Laramide orogeny. This event resulted in re-migration of gas into closed anticlinal traps. Fracturing is also responsible for permeability enhancement of the original low-grade reservoir. AOF tests as high as 3.1 × 106m3/d (110 MMcf/d) have been recorded.

The events leading to the discovery of the Sukunka-Bullmoose gas field provide an interesting exploration case history. The Sukunka a-43-B discovery well drilled in 1965 followed nine years of geological surface mapping, geophysical work and drilling in what was then a frontier exploration region. Delineation drilling of three dry holes and unsuccessful geophysical work by Triad and other operators demonstrated the difficulty of geological and geophysical interpretation of the area.

The modern and successful phase of exploration came in 1975, 19 years after the start of exploration when the Bullmoose d-77-E well discovered gas in a separate structure. Two successful wells on the Sukunka, one on the Bullmoose structure as well as discoveries at E. Sukunka and Murray River have been drilled in 1976 and 1977. To the end of 1977, BP and partners have spent $49 000 000 in the area. Production is expected to start in 1980.

Acknowledgments and Associated Footnotes

1 BP Exploration Canada Limited, Calgary, Alberta

2 BP Exploration Canada Limited, Calgary, Alberta

Copyright © 2009 by the Canadian Society of Petroleum Geologists