Injection optimization in CO_2 flooding for low permeability reservoir

The displacement efficiency of different scenarios has been studied through numerical simulation based on the conditions of a low permeability reservoir in Jillin oilfield.The simulation results indicate that alternating flooding can significantly improve oil recovery compared with water flooding and continuous gas flooding.In the process of alternating flooding,the order of gas and water slugs has a notable impact on oil recovery.Gas-alternating-water flooding is superior to water-alternating-gas flooding.The recovery factor increases with the increasing of gas injection rate.In gas-alternating-water process,CO2 can fully contact with crude oil,and the earlier CO2 is injected,the more favorable for enhanced oil recovery.The research has provided theoretical basis for CO2 flooding in low permeability reservoirs as well as meaningful reference in evaluating and planning of CO2 underground storage in China.