--> Abstract: Reservoir Development in the Devonian Wabamun Group: Examples from the Gold Creek and Pine Creek Fields, Alberta, Canada, by Ihsan S. Al-Aasm, Daniel Rivas, and Olugbemi (Mac) Amurawaiye; #90039 (2005)

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Reservoir Development in the Devonian Wabamun Group: Examples from the Gold Creek and Pine Creek Fields, Alberta, Canada

Ihsan S. Al-Aasm, Daniel Rivas, and Olugbemi (Mac) Amurawaiye
University of Windsor, Windsor, ON

The Wabamun carbonates at Gold Creek Field is highly fractured and brecciated when located on top of the underlying patch reef of the Leduc Formation. Fractures in the Wabamun increase towards the core of the reef core. This can be attributed to differential compaction between the reef framework and the surrounding shales causing reef collapse and thickening of subsequent Devonian and Mississippian strata. Such fractures are filled with a mélange of anhydrite, saddle dolomite, sulphides and pyrobitumen. In Gold Creek three main generations of dolomite were found: 1) matrix replacive dolomite, 2) compaction-related dolomite, and 3) cement dolomite. Petrographic examination of these dolomites show zoned matrix dolomites and variably luminescent late cements. This may reflect interaction with fluids of different chemical compositions. Geochemical evidence point to an early interaction (Late Devonian Early Mississippian) of the Wabamun carbonates with fluids of hydrothermal origin (Thmin=120°C-240°C, Sr87/86 from 0.7089 to 0.7133,δ18O from -2.7‰ to -15.5‰ VPDB). Radiogenic Strontium isotopic ratios and isotopic fluid modeling suggests that such fluids interacted with basement rocks as well.

Pine Creek facies are mudstone-dominated and with minor skeletal components. Several generations of dolomite observed in these carbonates formed during shallow to deep burial stages. The Normandville Member carbonates are depleted in δ18O (range=-6.25 to –11.31‰ VPDB for calcite and –3.13 to –11.65‰ VPDB for dolomite). δ13C values are near the postulated range of values for Devonian marine carbonates, except for late calcite cements that have low δ13C values (range= 1.54 to –26.33‰), due to incorporation of carbon-12 from sulphate-hydrocarbon redox reactions.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005