Reservoir Modeling and Simulation for CO2 Flooding: the
Effect of Reservoir Heterogeneity on Simulation Forecasts
Shaochang Wo,
Enhanced Oil Recovery Institute, Dept. 4068, University of Wyoming, 1000 E.
University Avenue, Laramie, WY 82070, phone: (307)766-2780,
fax: (307)766-2737, [email protected]
CO2 flooding has proven to be a viable enhanced oil recovery
process in many geographic locations. The Tensleep
Sandstone in the Bighorn and Wind
River basins, Wyoming,
contains the largest oil reserves in the state. Because of
reservoir heterogeneity, as little as 10-15% of discovered oil in the Tensleep Formation is recoverable by current primary and
secondary techniques. Many of the Tensleep
reservoirs are potential candidates for CO2 flooding. To evaluate the effect of
reservoir and fluid properties on CO2 flooding performance, a sensitivity study
of reservoir modeling was performed on a five-spot injection-production
pattern. A variety of reservoir configurations were simulated based on the
large range of API gravities of the oils produced from the Tensleep
Formation as well as its spatial variation and anisotropy of relative
permeability published from previous studies. CO2 flooding is generally not
sensitive to lithology but is sensitive to reservoir
characteristics. For the Tensleep reservoirs, the
actual performance of CO2 flooding will largely be controlled by the local
compartmentalization. The ECLIPSE compositional simulator was used for this
study.