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The AAPG/Datapages Combined Publications Database

CSPG Bulletin

Abstract


Bulletin of Canadian Petroleum Geology
Vol. 38 (1990), No. 1. (March), Pages 161-161

C.S.P.G. 1990 Convention, "Basin Perspectives"

Postulated Source(s) and Controls of Petroleum Accumulation in the Leduc Formation, Peace River Arch [Abstract]

Dix, G.R.*,2

ABSTRACT

Four petroleum fields (1.9times.gif (834 bytes)106m3 oil and a minimum of 5.7times.gif (834 bytes)109m3 gas - initial volumes in-place) occur within the Leduc Formation of the Peace River Arch area: Worsley (T87, R4-8W6) and Puskwaskau (T74, R1W6) are mainly gas and occur structurally downdip from Normandville (T79, R22W5) and Eaglesham (T77, R25W5) which are mainly oil. Petroleum accumulation seems to occur more commonly within dolomites that overlie buried terminations of paleovalleys of pre-Leduc age. Organic matter in Leduc carbonates is dominantly Type III and TOC is commonly less than 0.1 per cent. Vitrinite reflectance ranges between Ro=0.8 to 1.0, in the oil window. Comparison of available sterane and triterpane distributions for three oils suggests a common general source for Worsley, Normandville, and Eaglesham: a marine carbonate, greater than 360 my in age, with siliciclastic influx varying geographically. Other data indicate that both oils and their source(s) are mature and that depositional setting for the Worsley source was anoxic. The available data suggest that the Leduc Formation is not a likely source for in situ generation of gas, and potential for oil generation is low. Petroleum was most likely generated to the west of the present Arch and migrated into the Leduc, captured by secondary porosity (moldic, solution-fracture, fracture, intercrystalline) after fluids were channelled along paleovalleys and forced upward at the termination of these depressions, or along faults/fractures. The regional distribution of gas versus oil in the Leduc is probably more influenced by differential flow of oil and gas rather than by geochemical and burial parameters.

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ACKNOWLEDGMENTS AND ASSOCIATED FOOTNOTES

* Present Address: University of British Columbia, Vancouver V6T 2B4

2 Alberta Geological Survey, Edmonton T6H 5X2

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