Abstract
Immiscible water-alternating-gas injection (IWAG) has proven to be effective in managing produced gas at Kuparuk River Unit. The process is expected to improve oil recovery due to more efficient waterflooding in the presence of trapped gas. Laboratory data showed that trapped gas reduced water mobility by forcing water to displace oil from smaller pores. This mechanism resulted in lower residual oil saturation. Fully compositional simulation showed that IWAG may get an incremental oil of 1-3% of the original oil-in-place. Several years of operations have also revealed other significant tangible and intangible benefits for IWAG. These benefits are higher production rates, reduced water handling costs, and better reservoir management. Field experience shows that a tapered WAG helps keep produced gas oil ratio manageable. There are ongoing efforts to optimize WAG parameters (WAG ratio and gas slug size) and reduce costs. A potential injection scheme that does both is simultaneous water and gas injection.
