Geology-based Conditional Simulation in the Athabasca Oil Sands Deposit, Alberta, Canada R. Dimitrakopoulos ~ and W.H. Griffin 2 'Department of Mining and Metallurgi- cal Engineering, McGill University, Montreal, Quebec H3A 2A7, Canada, and 2Department of Mining, Metallur- gical and Petroleum Engineering,Uni- versityof Alberta, Edmonton, Alberta T6G 2El, Canada The Athabasca oil sands deposit, Alberta, Canada, is one of the largest known hydrocarbon accumulations. The efficient exploitation of this deposit, as well as other oil sand accumulations throughout the world, is based on in situ recovery and surface mining methods. Quantitative modeling of deposit heterogeneity provides a valuable engineering tool. In the present study, conditional simulation was used to model oil-saturated zones in part of the Athabasca deposit. This technique generates equiprobable models of the in s/tu variability of essential deposit attributes that honor the available data and their spatial sta- tistics. The application of the technique is based on the delineation of geologically homogeneous zones within the host McMurray For- mation, their statistical validity, and the integration of geological in- terpretations. The geological framework is developed, and subse- quently, high resolution conditionally simulated models of three identified hydrocarbon-bearing zones are generated, in terms of the zone boundaries and the percent weight of oil saturation. These mod- els serve as "'what-if" tools for risk assessment and future planning. Key words: Athabasca Oil sands Conditional simulation Variogram