Research progress and development trend of biochemical composite enhanced oil recovery technology

This paper systematically investigated the progress of laboratory research and field application of biochemical composite enhanced oil recovery technology in the past 10 years in China and abroad. The synergistic mechanism between oil recovery bacteria， biosurfactants， biopolysaccharides， and chemical oil recovery agents such as surfactants， polymers， and nanoparticles was discussed in terms of improving displacement efficiency and expanding swept volume， respectively. In addition， the system construction and field application effects were analyzed. The results show that the combination of biological bacteria and their metabolites with chemical oil recovery agents has synergistic effects on interfacial tension reduction， emulsification dispersion， mobility ratio control， and viscosity reduction of heavy oil， and the field application has achieved good application results. Bacteria polymer composite profile control and microbial desulfurization and viscosity preservation technologies were explored in Shengli Oilfield， and estimated recoveries reached 9% and 10.3%， respectively. Biological ASP composite technology was applied in Daqing Oilfield， and the recovery of the pilot area has been improved to 22%. The biochemical composite enhanced oil recovery technology has great potential for application in the exploitation of difficult-to-recovery reserves in mature oilfields. The next step is to continue to deepen the synergistic mechanism between biological and chemical systems， innovate the integration and implementation process of biological and chemical oil recovery systems according to the differences between reservoir planes and inter- and intra-layers， refine the implementation plan for different development stages and reservoir spaces， and maximize the advantages of biological and chemical synergistic efficiency enhancement technologies through the three-dimensional balanced development of reservoirs to satisfy the demand for sustainable development of mature oilfields.