Characterization, Geo-Modeling, and Reservoir Simulation of the Wabiskaw Member, Athabasca Oil Sands Deposit, Alberta, Canada

Abstract

Sunshine's West Ells SAGD project is located in Township 94 Range 17W4M. The average net pay thickness is 15 metres. The SAGD production wells are located at the base of the Wabiskaw D unit where the sands are fine to medium grained with lesser amounts of coarse grained sand. The core porosity is uniform and the average porosity is 33%. The average bitumen saturation is 71% but it can exceed 85% in rich intervals. The average horizontal and vertical permeability is 2.4 D and 1.7 D, respectively. Within the shallow marine environment at West Ells, the shoreface sands are condensed and the contact between the Wabiskaw D and overlying Wabiskaw C is subtle. The vague boundary is informally called the C/D transition zone. The C/D transition zone is approximately 2 metres thick and the mud content is minor but variable. The mud content can be non-existent or there can be several mud laminae and beds that range in vertical thickness from mm to cm. The muds are interpreted to be deposited as drapes in hummocky cross-stratified sands. The maximum lateral extent and vertical relief of the mud drapes are inferred to be 5-8 metres and 20-50 centimetres, respectively. A detailed characterization of the mud distribution within the C/D transition zone was undertaken to provide input for reservoir simulation. The simulation had three objectives. (1) Quantify the impact of mud drapes in the C/D transition zone on steam chamber growth and bitumen recovery. (2) Assess the effect of vertical grid size on reservoir simulation results. (3) Assess the effect of various percentages of mud drapes on steam chamber growth and bitumen recovery. There is no current production history to verify the steam chamber growth within the Wabiskaw Member, and in particular, through the C/D transition zone. However, field results will be available in 2016. To monitor the steam chamber growth, there are 7 observation wells equipped with temperature and pressure gauges. They are located very close to the SAGD well pairs and are within 1.1 to 10.6 metres.

AAPG Datapages/Search and Discovery Article #90259 ©2016 AAPG Annual Convention and Exhibition, Calgary, Alberta, Canada, June 19-22, 2016