Modeling of a Tide-influenced Point-bar Heterogeneity Distribution and Impacts on Steam-assisted Gravity Drainage Production: Example from Steepbank River, McMurray Formation, Canada
Geoffray Musial, Richard Labourdette, Jessica Franco, Jean-Yves Reynaud, 2013. "Modeling of a Tide-influenced Point-bar Heterogeneity Distribution and Impacts on Steam-assisted Gravity Drainage Production: Example from Steepbank River, McMurray Formation, Canada", Heavy-oil and Oil-sand Petroleum Systems in Alberta and Beyond, Frances J. Hein, Dale Leckie, Steve Larter, John R. Suter
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Outcrops and subsurface investigations emphasize that the main bitumen reservoirs of the McMurray Formation are large point-bar deposits. Sedimentological studies performed on these reservoir objects have shown that tidal currents occurred in the meandering paleo-river system. These tidal inputs increased reservoir heterogeneities primarily because of successive mud decantation periods and the many reactivation or erosion surfaces. Five main reservoir heterogeneities have been described on Steepbank River outcrops: mud accumulation during channel abandonment, mud drapes along accretion surfaces that are downward interfingered into cleaner sands, flood-plain deposits on top of the point bar, reactivation surfaces typically associated with mud-clast deposits, and mud-clast breccias accumulated at the base of the channel. At the same time, five main facies have been emphasized on these studied tide-influenced point bars: mud-clast breccias, cross-stratified sands, slightly heterolithic rippled sands, highly heterolithic burrowed sands, and thick mudstones. For each of these facies, petrophysical properties have been established, enabling their application as rock types for the Steepbank River outcrop modeling. This deterministic method of modeling, improved by light detection and ranging (LiDAR) data, used truncated Gaussian simulations constrained by the proportion cube, sedimentological logs corresponding to hard data, and adequate variograms. The resulting facies and heterogeneity distributions conform closely to the outcrop reality, lending support for the modeling method.