Smart Process to Manage and Rationalize the Water Flood in Highly Heterogeneous Complex Carbonate Reservoir

Summary The Voidage Replacement Ratio (VRR) is used to assess the performance of ongoing water floods. Often, it has been experienced that VRR is either used or abused during waterflood management, which leads to inconsistent decisions. Integration of VRR with injection efficiency provides a powerful tool to manage mega-sized water floods in North Kuwait. This article presents various sources of errors in reporting VRRs and suggests a deep-dive approach rather than a simplistic methodology. The North Kuwait Reservoirs’ portfolio of active water flooding includes componentization, depletion drive mechanisms, weak aquifer support, and injected water recirculating to nearby producers. A comprehensive review integrating all available data was conducted to better understand the subsurface of reservoirs. Once the physics of the flow of injected water were known, the VRRs were computed using data-based artificial intelligence rather than a single value from a simple volume-to-volume ratio for each reservoir. To make quick decisions, smart water flood segment reviews were carried out using diagnostic plots, injection efficiency, and artificial intelligence to scale the VRR for each segment of the reservoir. Various kinds of VRRs are computed, such as instantaneous VRRs, cumulative VRRs, VRRs for areas below bubble point pressure, VRRs for the active segments or patterns, VRRs in pure depletion mode, VRRs under an aquifer support scenario, and VRRs with quick re-circulation or thief zones. Once all of these values are known, the management of the field, segment, or pattern is done in accordance with the reservoir requirements to scale the allowable and redistribute the injected water for maximum benefit. In addition, the VRRs could address reservoir heterogeneity and connectivity to some extent, which would assist the team in making prudent decisions to plan activities for improving water injection efficiency. Various visualization tools using OFM and Spotfire help in decision-making under the collaborative platform. Using these strategies, the water flood optimization in the Sabiriyah Mauddud (SAMA) reservoir resulted in a 10% reduction in re-circulation water and generated stable water cut performance during the previous years. The possibilities of either an over- or under-injection in any part of the SAMA reservoir are avoided. A powerful option to incorporate performance-based VRRs and water injection efficiency with a rigorous approach helped the team utilize the water injection resources smartly.