Pore-scale study on flow characteristics and enhanced oil recovery mechanisms of polymer microspheres in microchannels

Polymer microsphere flooding is a promising technology for enhancing oil recovery in high water cut reservoirs. Nevertheless, the microscopic flow characteristics and oil recovery mechanisms remain unclear. In this paper, the retention and flow diversion characteristics were investigated by single-microchannel and dual-microchannel chips, respectively. On this basis, the microscopic conformance control and oil recovery performance were studied by pore network model experiments. The influence of concentration and injection rate was discussed. The findings indicate that the polymer microspheres present the discontinuous phase flow characteristics of “temporary plugging-pressurizing-deformation-remigration” in microchannels. They realize flow diversion by alternately plugging wide and narrow microchannels. In porous media, they can inhibit fluid fingering and improve sweep efficiency. As the concentration increases, the sweep efficiency and the oil recovery improve, while the increase in injection rate leads to the opposite result. This work provides microscopic insights into the flow and oil recovery mechanisms of polymer microspheres.