Unlocking Opportunity Kotatua Field “X-2 Sand’; Low-Quality Reservoir and Depleted Reservoir Pressure Through Waterflood

Abstract

Asset Optimization South team has successfully increased oil production in Kotatua Field by initiating water injection in the “X-2” sand. The “X-2” sand has low permeability and has historically been produced commingled with the Bravo sand, which has higher permeability. The Bravo sand has been waterflooded since 1974, while the “X-2” reservoir has been pressure depleted to the point of negligible. “X-2” pressure rejuvenation started in May 2018 with conversion of 6 commingled injectors and 1 commingled producer converted become single completion and dedicated as a pilot. During the monitoring of the waterflood response, apart from BHP monitoring, the extensive oil fingerprinting analysis was accrued out to determine oil allocation and zonal contribution. After observing the waterflood response, the project was expanded in 2019 by converting 3 more injectors and workover 16 producers to single completion of “X-2’ sand. End of 2019 the project has successfully delivered incremental 2,589 BOPD equivalent to 746 MSTB cumulative with a total expenditure of US$ 1.0 MM. It delivered additional reserves 3.7 MMSTB until August 2022.