Steam injection performance in heterogeneous reservoirs

A vertical steamdrive and cyclic steam injection were simulated numerically and evaluated for viscous oil recovery from homogeneous and heterogeneous reservoirs. A horizontal well pair was used in the vertical steamflood, while cyclic steam injection was carried out with both vertical and horizontal wells. Reservoir heterogeneity was varied through the use of 'stochastic shale realizations' incorporated into the simulator model. Sensitivity studies investigated the effect of shale size and frequency as well as the effect of injector-producer spacing and completion interval on oil recovery. For any shale size oil recovery in the vertical steamdrive improved at the higher shale frequencies but was adversely affected at low frequencies. Larger spacings generally gave improved recoveries. Recoveries from horizontal well cyclic stimulation decreased monotonically with increase in shale size and frequency. Vertical well performance was not affected for a fully completed well, partial completions were adversely affected by the shales.