Dispersed Particle Gel-Strengthened Polymer/Surfactant as a Novel Combination Flooding System for Enhanced Oil Recovery

A novel dispersed particle gel-strengthened polymer surfactant (DPS) combination flooding system was proposed and demonstrated for enhanced oil recovery in high water cut mature oilfields. As compared to a conventional polymer surfactant (PS) combination flooding system, DPS systems have a higher viscosity and a more stable network structure. The polymer is mainly a source of the viscosity, while the surfactant plays a key role in reducing the interfacial tension (IFT). The added dispersed particle gel (DPG) has a synergistic viscosity increase effect, whereas for the DPG particles, the salinity and aging time have a slight effect on the IFT reduction capacity of the DPS system. On the basis of sand-pack flowing experiments, the DPS system has a better mobility control capacity than the PS system in the combination flooding stage and the following water flooding stage. Parallel sand-pack flowing experiments indicate that injection of a DPS system can effectively improve the profile control. The added DPG particles could intersperse in the three-dimensional network structure, which increases the stability of the DPS system in solution and porous media. Through the improved synergistic effect of the swept volume capacity and high displacement efficiency, the oil recovery capacity of the DPS system is significantly enhanced. The DPS system may be an alternative for enhanced oil recovery in other similar high water cut mature oilfields.