Research Progress on Enhanced Oil Recovery by CO2 Flooding in Low Permeability Reservoirs

Summarized the current development situation of low permeability oil reservoirs at home and abroad, and sorted out the development process of three stages: indoor research, pilot testing, and field application of CO2 flooding at home and abroad. The micro oil displacement mechanism in the CO2 oil displacement process was systematically elaborated, and some widely used calculation methods for the minimum miscibility pressure (MMP) of CO2 and crude oil were summarized, providing a theoretical basis for significantly improving oil recovery. On the basis of tracking and researching the on-site application and effectiveness of CO2 flooding technology for improving oil recovery in 33 low permeability reservoirs both domestically and internationally, 5 rock properties and 2 fluid properties of reservoirs using CO2 flooding method were summarized, and the impact of 2 displacement modes and 5 injection methods on CO2 flooding efficiency was analyzed. The research results indicate that the displacement method of the miscible flooding and the injection method of periodic gas injection have better CO2 oil displacement effect. Provide on-site application reference and experience support for the efficient application of CO2 flooding technology to improve oil recovery in low permeability reservoirs in China.