Comprehensive Performance Optimization of a Water-Alternating-Carbon-Dioxide Reservoir

Abstract

An evolution-based algorithm is applied to comprehensively optimize a field scale reservoir developing process, spanning from the primary production to the waterflooding and then the miscible water-alternating-CO2 (CO2 WAG) process. Effects of 98 operational parameters on the net present value (NPV) are analyzed and quantified, including the primary production duration, water injection rates during the waterflooding process, process onset time, gas and water injection rates of CO2 WAG process and producer bottomhole pressure (BHP) during each production stage. The impacts of geological uncertainty are evaluated using multiple reservoir realizations. It has been found that durations of the primary production and waterflooding processes have the most pronounced impact on the final NPV. The oil recovery of the comprehensive optimization scenario has been enhanced by 23.37% compared to that of the conventional WAG optimization. This is mainly due to the shorter durations of the primary and waterflooding processes.