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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 163-163

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

Importance of the Reservoir/Cap Rock Contact in Assessment of Undiscovered Petroleum Resources [Abstract]

Forman, D.J.1, Hinde, A.L.1, Radlinski A.P.1

ABSTRACT

Most petroleum migrates into traps along the contact between the reservoir and cap rocks. The number and size of petroleum accumulations that result depend largely on the interaction between the geometry of this surface and the quantity of hydrocarbons migrating upward to it, and then along it. In a simple trap, the petroleum migrating within the area of drainage will be funnelled into the area of closure. The funnelling effect is proportional to the ratio of the area of drainage to the area of closure, which in turn depends on the type of trap, its shape, and its tilt. Petroleum may also be added or lost by over-spilling from, or into, an adjacent trap. In more complex traps with a number of culminations, petroleum will initially be funnelled into a number of small accumulations. As more petroleum is added, these will coalesce into one accumulation, which may then overflow.

Where there are sufficient data, plays can be outlined by regional drainage divides drawn onto structure contour maps that also show the areas of drainage and closure of the traps and the likely migration paths. Plays containing complex traps can be further subdivided. Where a trap has two or more culminations, the enclosing trap belongs to the one play and the culminations within it belong to another. Further fractal plays are possible if there are culminations within the culminations. A better assessment is obtained if each play is assessed separately.

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ACKNOWLEDGMENTS AND ASSOCIATED FOOTNOTES

1 Bureau of Mineral Resources, Canberra, ACT 2601, Australia

Copyright © 2003 by The Society of Canadian Petroleum Geologists. All Rights Reserved.