Comprehensive evaluation of a novel EOR method-coupling low salinity water flooding and preformed particle gel to enhance oil recovery in fractured reservoirs

Excess water production in oil fields is becoming a challenging economic and environmental problem as more reservoirs are maturing. Water channeling, one of the primary reservoir conformance problems, is caused by reservoir heterogeneities that lead to the development of high-permeability streaks. The recovery of oil from carbonate reservoirs is usually low due to their extreme heterogeneity caused by natural fractures and the nature of oil-wet matrix. Also, oil recovery from fractured sandstone reservoirs is often low due to areal heterogeneity. Gel treatments have proven to be a successful and inexpensive fluid diversion method when used to plug the thief zones and thereby improve sweep efficiency in reservoirs. However, particle gel treatment can only be used to plug fractures or high permeable channels to improve sweep efficiency and has little effect on displacement efficiency. Oil recovery is the product of displacement efficiency (ED) and sweep efficiency (ES). Particle gels can plug fractures and improve sweep efficiency, but they have little effect on displacement efficiency. Low salinity water flooding (LSWF) can only increase displacement efficiency but has little or no effect on sweep efficiency. The main objective of this research is to provide a comprehensive understanding of the combined LSWF-PPG technology and to show how the coupling method can improve oil recovery. We developed a cost-effective, novel, enhanced oil recovery (EOR) technology for fractured reservoirs by coupling the two technologies into one process. The coupled method bypasses the limitations of each method when used individually and improves both displacement and sweep efficiency --Abstract, page iv