Research on the Oil Displacement Effect of Binary Composite System on High Water Content Heavy Oil Reservoirs

The development of water injection in heavy oil reservoirs often progresses to a late stage characterized by high water content. During this phase, more than 70% of the remaining oil is retained within the reservoir, making its recovery challenging. Consequently, there is an urgent need to identify suitable displacement systems to enhance recovery efficiency. This study examines a specific heavy oil field located offshore China, focusing on the effects of mobility control and low interfacial tension on the oil displacement efficacy during chemical flooding. The findings reveal that the oil displacement performance of a binary composite system surpasses that of a single system. The synergistic effects of the composite system are advantageous for extracting residual oil from low-permeability layers. Notably, the contribution of mobility control within the composite system (54.88%) is greater than that of low interfacial tension (45.12%). Only effective mobility control through the use of polymers can enhance the efficacy of surfactants. Furthermore, variations in the solution properties of composite systems can significantly influence the oil displacement outcomes. The binary composite system, which primarily employs mobility control and appropriately reduces interfacial tension, is more effective for enhancing the recovery rate of water-flooded high-permeability heavy oil reservoirs in the later stages.