Polymeric microsphere injection in large pore-size porous media

Abstract

High water-cut has become a worldwide challenge for oil production. It requires extensive efforts to process and dispose. This entails expanding water handling facilities and incurring high power consumption costs. Polymeric microsphere injection is a cost-effective way to deal with excessive water production from subterranean formations. This study reports a laboratory investigation on polymeric microsphere injection in a large volume to identify its in-depth fluid diversion capacity in a porous media with large pore/particle size ratio. The performance of polymeric microsphere injection was evaluated using etched glass micromodels based on the pore network of a natural carbonate rock, which were treated as water-wet or oil-wet micromodels. Waterflooding was conducted to displace oil at reservoir temperature of 95 °C, followed by one pore volume of polymeric microsphere injection. Three polymeric microsphere samples with median particle size of 0.05, 0.3, and 20 μm were used to investigate the impact of particle size of the polymeric microspheres on incremental oil production capacity. Although the polymeric microspheres were much smaller than the pores, additional oil production was observed. The incremental oil production increased with increasing polymeric microsphere concentration and particle size. As a comparison, polymeric microsphere solutions were injected into oil-wet and water-wet micromodels after waterflooding. It was observed that the oil production in oil-wet micromodel was much higher than that in water-wet micromodel. The wettability of micromodels affected the distribution patterns of the remaining oil after waterflooding and further dominated the performance of the microsphere injection. The study supports the applicability of microsphere injection in oil-wet heterogeneous carbonates.