Reservoir geology of the Grosmont Formation Bitumen Steam Pilot, Saleski, Alberta

Abstract The Grosmont Formation, with an estimated resource of 64.5 billion m3 (406 billion bbl), is one of the largest bitumen deposits in the world. The Grosmont Formation contains four stacked carbonate units. The uppermost two, the Grosmont C and D, contain the bulk of the Grosmont bitumen resource. The Grosmont C reservoir interval is 20 m thick and consists mainly of vuggy dolomite with an average porosity of 18.6%. The overlying 32 m thick Grosmont D has an average porosity of 24.3% and its main reservoir facies is dolomite breccia. Bitumen and water saturations are variable throughout the reservoir and require either core analysis or exotic logging tools such as nuclear magnetic resonance logging for accurate determination. One outcome of the improved understanding of bitumen saturations within the Grosmont reservoirs was the identification of a lean bitumen zone within the Grosmont D. Through the use of radioactive tracer logs, it was determined that this zone is a major drilling fluids thief zone. Laricina Energy Ltd. and Osum Corp. are conducting a cyclic steam assisted gravity drainage (SAGD) pilot at Section 26 Twp 85 Rge 19W4M using horizontal wells in both the Grosmont C and D. The pilot has produced 79 500 m3 (500 000 bbl) of bitumen up to February, 2015.