ABSTRACT

The Wabamun Group consists of cyclical, shoaling upward, shallow water carbonates and evaporites deposited on a wide shelf. Data from the subsurface Tangent, Eaglesham, and Normandville fields indicate that these originally nonporous, subtidal carbonates have undergone a complex diagenetic history resulting in the highly variable distribution of reservoir rocks.

Primary porosity was reduced by sea floor and early burial diagenesis. Limestone diagenesis includes micrite, syntaxial overgrowth, granular, blocky, and fracture-filling cements. Mechanical compaction, minor dissolution, and early fracturing occurred prior to significant dolomitization.

Dolomites consist of: 1) early microdolomite and floating rhombs; 2) intermediate mosaic and stylolite - precipitated dolomites; and 3) later sucrosic, saddle, fine crystalline, and cap dolomites. Fracturing, brecciation, and dolomitization occurred in several stages, possibly associated with faults. The porosity and permeability of these rocks were increased locally, thereby creating potential hydrocarbon reservoirs.

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