Onshore and Shallow Offshore Beaufort-Mackenzie Basin, Northern Canada

A. P. Hemingson, B. L. Collot

Since 1965, 164 exploratory wildcats have been drilled in the Beaufort-Mackenzie basin of northern Canada, resulting in 51 discoveries of oil and/or gas. The Geological Survey of Canada estimates of discovered reserves in these fields amount to more than 10 tcf of gas and 1.2 billion bbl of oil. The petroleum habitat for the onshore and shallow offshore (< 30 ft isobath) portions of the basin, where 31 of these multipool oil and gas discoveries have been made, is still not fully delineated.

Two petroleum provinces with different play types have been identified in this portion of the basin.

1. The southeast margin province includes the Tuk Peninsula and the central onshore Mackenzie delta. Here, tilted fault blocks involving Lower Cretaceous sandstones have been the main play type since the first oil discovery at Atkinson Point in 1970. However, the largest single oil accumulation in this part of the basin was found in shallow Tertiary sands in 1985 near the community of Tuktoyaktuk. In addition, minor discoveries have also been made in Paleozoic carbonates. To date, 76 wildcats resulting in 12 discoveries of oil and gas have been drilled in this area. Geochemical typing of the oils has fingerprinted the dominant source rocks to be Lower Cretaceous shales, primarily the Boundary Creek Formation, a dark, organic-rich, marine shale.

2. The second petroleum province underlies the northern part of the modern-day Mackenzie delta, and includes Richards Island and the shallow offshore. Faulted anticlines involving lower Tertiary regressive sand wedges are the main play type. In this area, 46 wildcats have resulted in 19 discoveries. The identification of source rocks in this province is more illusive, but geochemical studies suggest that lower Tertiary shales, dominated by terrestrial organic matter, likely constitute the main source.

AAPG Search and Discovery Article #91030©1988 AAPG Annual Convention, Houston, Texas, 20-23 March 1988.