Volume 56

Study on Enhancing Oil Recovery Factor Mechanism of Complex Fault Block Reservoir by WAG Flooding Yong Tang, Chen Yinuo, Qin Jiazheng, He Youwei, Duan Shengcai

Abstract

At present, CO2 is one of the main media for gas injection to enhance oil recovery in low permeability reservoirs with good mining application. The development of complex fault block reservoirs has problems such as strong non-homogeneity, difficult injection, low production, etc. In this paper, we carried out a study on the mechanism of WAG flooding to improve the recovery rate in complex fault block reservoirs. Firstly, using 2D profile experiments, it is clarified that gravity overlap and the expansion of swept volume in WAG flooding are the main mechanisms for production increase. Secondly, phase fitting is carried out by combining the field geological data and production data to provide a fluid model for the subsequent numerical simulation study. Finally, the reservoir development method as well as the injection and recovery parameters are studied separately based on the injection and recovery well network model. The simulation results show that the current gas injection pressure can realize the miscible flooding, and the WAG flooding schedule has strong adaptability. The influence of parameter was analyzed through a single factor sensitivity analysis to obtain the optimal injection and extraction parameters. Among them, the well spacing is the main factor affecting the WAG flooding. The results of this study have an important guiding role for the design of CO2 flooding in complex fault block reservoirs.

Keywords CCUS, low permeability reservoir, CO2 flooding, WAG, parameters optimization