Improving Oil Recovery Using Sub-Micron Particle Gel for Sandstone Reservoirs

Reservoir conformance is a major issue to limit oil recovery because injection fluids preferentially flow through higher permeability zones and thus leave significant oil in unswept low permeability zones/areas. Particle gels have been successfully applied to solve the reservoir conformance problem in mature reservoirs. This work investigated the oil displacement efficiency of a polyacrylamide-based sub-micron preformed particle gel polymerized by acrylamide and N,N'-Methylenebisacrylamide via suspension polymerization using sandstone porous media. In this study, core flooding experiments were conducted to investigate the impact of crosslinking density of the sub-micron gel and rock permeability on oil recovery improvement. Results found that the sub-micron gel synthesized by lower concentration crosslinker yielded in higher oil recovery improvement when the rock permeability were in the same range. The sub-micron gel had higher oil recovery improvement in lower permeability rock. In addition, the gel had higher plugging efficiency when it was prepared by lower concentration crosslinker or injected to higher permeability rock. The residual resistance factors were insensitive to injection flow rate.