ABSTRACT: A Unique Dolomite Reservoir: The Upper Devonian Grosmont Formation in Northeastern Alberta, Canada

HUEBSCHER, H., E. DEMBICKI, and H. G. MACHEL, University of Alberta, Edmonton, Alberta, Canada

The objective of this project is to investigate the diagenesis and reservoir characteristics of the Grosmont Formation, which is the only heavy-oil (bitumen) carbonate reservoir in Canada. Some 100 wells have been studied for facies, diagenesis, porosity, permeability, and bitumen saturation of the Grosmont Formation, and of the underlying and overlying strata (where cored). We identified several diagenetic phases of porosity and permeability generation and destruction. Most porosity can be grouped into three categories, and dolomite, the main diagenetic mineral, forms at least three textural types and four petrophysical types. Petrographic, stable, and radiogenic isotope data suggest that most dolomite formed early diagenetically from seawater and/or evaporated seawater. To date, the Grosmont Formation is the only dolomitized carbonate platform in Canada where an early diagenetic origin of most dolomite appears certain.

The occurrence, extent, and characteristics of dolomites and associated evaporites are under further investigation. All petrographic data will be integrated with petrophysical reservoir types in order to determine the spatial distribution and origin of reservoir characteristics.

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