Saskatchewan and Northern Plains Oil & Gas Symposium Core Workshop Volume 2006, Saskatchewan Geological Society Special Publication 20. Editor: Erik Nickel. Pages 59-59.

Abstract: A New Exploration Strategy for Lower Paleozoic Petroleum Systems in the Williston Basin

K.G. Osadetz¹, F.M. Haidl², B.P. Kohn³, S. Feinstein⁴, L.K. Kreis², and P.B. O'Sullivan^5
1 Geological Survey of Canada, 3303 3rd St. NW, Calgary, Alberta T2L 2A7
² Saskatchewan Industry and Resources, 201 Dewdney Ave E. Regina, Saskatchewan S4N 4G3
³ School of Earth Sciences, University of Melbourne, Victoria 3010, AUSTRALIA
⁴ Department of Geological and Environmental Sciences, Ben Gurion University of the Negev, P.O. Box 653, Beer Sheva 84 120, ISRAEL
⁵ Apatite to Zircon Inc., 1075 Matson Road, Viola ID. 83872-9709 United States of America.

Petroleum is produced from the Sauk (M. Cambrian-L. Ordovician) and Tippecanoe (M. Ordovician-Silurian) successions in Williston Basin. The best potential reservoirs are found in Deadwood Fm. sandstones (U. Cambrian- L. Ordovician), Winnipeg Gp. sandstones (M. Ordovician), Bighorn Gp. carbonates (U. Ordovician-L. Silurian) and the Interlake Gp. carbonates (Silurian). Large proven and produced reserves occur in the United States, especially in basement-involved, long-lived structures such as Cedar Creek and Nesson anticlines. Efforts to extend this production into Canada have led to conceptually important discoveries, but reserves and reservoir performance have not matched those of American fields. Petroleum systems analysis indicates at least three petroleum systems in this interval. The most important is the Bighorn-sourced oil from kukersitic source rocks. Other petroleum systems have sources in Winnipeg Gp. shales and an as yet unlocated interval inferred to occur in the Deadwood Fm. The former produces oils resembling those with source rocks in the Bighorn Gp., while the latter produces oils that resemble oils with sources in the Devonian succession, although they have distinctive stable isotopic compositions. Geophysics, organic maturity and apatite fission track thermochronology indicate geographic and temporal variations in basement heat flux controlled by geodynamics. The primary effect of thermal history variations is significant petroleum generation during the Carboniferous and Permian. Exploration success hinges on the timing and preservation of trap formation relative to petroleum generation. Therefore, the recent strategy of drilling current structural highs should be augmented by a search for ancient structural and stratigraphic traps, of which Cedar Creek Anticline is the best example.

Keywords: Ordovician, carbonates, Red River Formation, Saskatchewan, kukersite, apatite fission track thermochronology

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