ABSTRACT: The Keg River/Winnipegosis Petroleum System in Northeast Alberta

KIRKBY, KENT C., University of Wisconsin-Madison, Madison, WI, and SCOTT W. TINKER, Marathon Oil Co., Littleton, CO

Considerable potential exists for significant hydrocarbon reserves in the Keg River/Winnipegosis (Givetian) outer shelf margin of northeast Alberta. Lower Keg River/Winnipegosis sediments were deposited in shallow water (<75 m) as a carbonate ramp. Contemporaneous (mid-Devonian) faulting and uplift initiated development of a platform margin composed of stacked, porous (15-25%) packstone and grainstone shoals. Pinnacle reef and bank growth in the basin were contemporaneous with shelf deposition. Restriction of the basin ended carbonate deposition and initiated deposition of the Muskeg/Prairie Formation evaporites that form the seal for most Keg River/Winnipegosis production.

Keg River oils from the Senex/Utikuma Lake area (southwest of the shelf margin) comprise a homogeneous, migrated oil family that is markedly more mature than its host strata. The Duvernay Formation (Upper Devonian) apparently sourced this oil. Epi-fluorescence (E-F) study of 200 thin sections delineates long-distance (>320 km) oil migration routes through the thermally immature Keg River carbonates of northeast Alberta. Drill-stem test recoveries and E-F oil shows demonstrate that oil migration extended northeast of the Senex area to the Keg River shelf margin. Epi-fluorescence study suggests that the margin deflected oil migration to the southeast, oblique to regional dip. These data reveal a long ribbon of prospective margin strata continuing almost to the Saskatchewan border, wh re pre-Cretaceous evaporite dissolution removed the overlying seal.

Successful exploration of this margin depends upon understanding the fault control of depositional facies and recognition of local Muskeg anhydrites that seismically mask the carbonate shelf margin.

AAPG Search and Discovery Article #91012©1992 AAPG Annual Meeting, Calgary, Alberta, Canada, June 22-25, 1992 (2009)