A Novel Water Ionic Composition Optimization Technology for SmartWater Flooding Application in Carbonate Reservoirs

Abstract Injection water with selective ionic content and composition is an essential requirement for SmartWater flooding application in carbonate reservoirs. SmartWater depleted in monovalent ions, but enriched in sulfates and divalent cations is desired for optimum incremental oil recovery in carbonates, which constitutes very complex water chemistry when compared to sandstones. Recognizing the utmost importance of water chemistry in the SmartWater flooding application, a novel water ionic composition optimization technology was investigated in this study. The proposed technology makes use of membrane desalination processes in a unique configuration to provide multiple water streams of widely varying ionic strength and content. Different water streams obtained from the novel solution can be effectively blended to yield SmartWater cocktail of desired ionic strength, composition and monovalent to divalent ion content optimally suited for carbonates. SmartWater cocktails obtained from the proposed solution are also suited for application in other EOR processes such as polymer flood, surfactant flooding, dilute surfactant flooding, carbonated water flooding, miscible gas flooding and as boiler feed water in steam floods. Investigated scheme thereby offers a novel "one shop" solution to meet the complete suite of desired water chemistry requirements for different IOR/EOR processes. In addition, results of comparative evaluation between the investigated technology and other already known advanced desalination schemes highlight key advantages of the new solution in terms of better water ion tuning flexibility, higher recovery efficiency, lower energy requirement/foot-print and ease in operation.