10. Review of Geology of a Giant Carbonate Bitumen Reservoir, Grosmont Formation, Saleski, Alberta

Abstract

Introduction The Grosmont Formation is an Upper Devonian carbonate succession that is present in northeastern Alberta. It contains 318 billion barrels of bitumen on the basis of Alberta government estimates (Alberta Energy Resources Conservation Board, 1996). Figure 1 is a map of the interpreted bitumen resource on the basis of Energy Resources Conservation Board mapping. This map also shows the location of Laricina Energy's Saleski land block in the heart of the bitumen accumulation. During the winters of 2006–2007 and 2007–2008, Laricina Energy drilled 21 vertical wells for the purposes of bitumen resource delineation. In addition, one horizontal well was drilled as part of a proposed steam-assisted gravity drainage (SAGD) pilot. The Grosmont Formation is a 120-m thick carbonate succession that is sandwiched between shales of the Upper and Lower Ireton Formation within the Woodbend Group. It has been subdivided chronologically into the A, B, C, and D units. These subdivisions correspond to Cutler's (1983) units LG, G1, G2, and G3, respectively. The lowermost three units were deposited during shallowing-upward depositional cycles. The uppermost unit, the Grosmont D, is an aggradational depositional unit. Grosmont strata dip gently to the southwest. The Grosmont has been bevelled by erosion in an easterly direction.