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The AAPG/Datapages Combined Publications Database

CSPG Special Publications


Facts and Principles of World Petroleum Occurrence — Memoir 6, 1980
Pages 988-988
Symposium Abstracts

Salt Removal and Oil Entrapment: Abstract

Roger H. Edmunds1

Salt removal is one of the major, if not the most important hydrocarbon trapping mechanism in Western Canada. This phenomenon not only produces major trapping by creating simple structural reversal along the updip basin rim, but through contemporaneous salt removal at time of deposition of the reservoir and through multi-stage removal creates more complex structural stratigraphic trap conditions. Salt removal is the primary trapping mechanism for the trillion barrel belt of Lower Cretaceous heavy oil and oil sand deposits which stretches along the rim of the Western Canada Basin from the Cantaur-Success Field Area of Saskatchewan to the Athabasca Oil Sands Area of Alberta. The oil trapping has been brought about by removal of salt from the Middle Devonian Elk Point Group during Cretaceous and possibly early Tertiary time. Another major producing trend, the Nipisi-Mitsue Middle Devonian Gilwood Sand Trend, containing in excess of 79.4 × 106m3 (500 million barrels), is stratigraphically trapped, with the trap being created by removal of salt from the Elk Point during Gilwood time. A multitude of other smaller trapping situations due to salt removal are evident in Western Canada, in the United States portion of the Williston Basin and in the Michigan Basin. In Western Canada removal of salt from the Upper Devonian Wabamun and Woodbend Groups, in addition to the Middle Devonian Elk Point Group, has produced oil and gas traps. Multiple stage differential salt removal has created complex traps such as the Hummingbird in Southeastern Saskatchewan. Inlier traps, such as the Westhope field in North Dakota, are a result of local late Mississippian salt removal preserving the producing beds from post-Mississippian erosion. Salt remnants of the Silurian Salina Group in the Michigan Basin have created structural drape traps in overlying beds.

Salt removal, besides creating trap conditions, significantly affects the mapability of underlying reef accumulations and in mapping of prospective trends. The Zama-Rainbow Middle Devonian Keg Reef Trend of Northern Alberta and the Silurian Niagaran Reef Trend of Michigan are examples of salt removal affecting the geological and geophysical mapping. Salt removal requires a much more prominent place in the world oil literature.

Acknowledgments and Associated Footnotes

1 Edmunds Resources Limited, 8915 Baylor Crescent, Calgary, Alberta

Copyright © 2009 by the Canadian Society of Petroleum Geologists