--> Abstract: Reservoir Modeling to Address Steam-Assisted Gravity Drainage (SAGD) Simulation and Heterogeneity Scales, Surmont Lease, McMurray Oilsands, Alberta, by David Garner and Thomas J. Wheeler; #90039 (2005)

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Reservoir Modeling to Address Steam-Assisted Gravity Drainage (SAGD) Simulation and Heterogeneity Scales, Surmont Lease, McMurray Oilsands, Alberta

David Garner and Thomas J. Wheeler
ConocoPhillips Canada, Calgary, AB

Thermal reservoir simulation for history matching SAGD extraction of bitumen sands presents challenges in model building. The interaction of the heat transfer processes and geological heterogeneity need to be addressed. The Cretaceous McMurray formation is a highly heterogeneous clastic reservoir with thick, bitumen-saturated sands. Within the reservoir sands there are persistent mud layers, which vary in thickness and spatial continuity. The approaches we used to geostatistically model the facies and hence heterogeneity of reservoir parameters had a significant impact on our ability to reasonably simulate steam chamber growth and shape.

Initial efforts focused on using conventional geomodel grid sizes and downscaling the reservoir properties through grid refinement. The steam chamber growth and shape did not match field data. The chamber was too wide and vertical development was halted at the muds. The mud layers were too continuous, and the sands were too homogeneous, in spite of the refined grids.

We used our large area geostatistical model as pseudo wells for conditioning a local fine grid SAGD well pair model. Each realization was resimulated in the fine scale grid providing a downscaling that honored the wells, area geomodel, and reproduced local heterogeneity. The model was rescaled for thermal simulation efficiency. Then the simulated steam chamber growth and shape fit our measurements, and the history matching was greatly improved.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005