B Block CO₂ Injection Pattern Optimization And Oil Displacement Mechanism

The B-block is a typical low-permeability reservoir with strong reservoir heterogeneity,high clay content and strong sensitivity.At present,the common water injection and other development methods have low effect on the exploitation of low permeability reservoir.the recovery rate of the block is only 11.4%,the oil recovery rate is only 0.35%.Nowadays,the main problem is that there is water injection channeling in the process of fracturing and production,low oil production speed,low recovery degree and poor development effect.The contradiction between water injection development has seriously restricted the effective development of low permeability oilfield,and it is urgent to find effective.The development of technology to solve the current low-permeability reservoirs facing low-speed,inefficient,difficult to use,low recovery rate of development.The CO₂ flooding technology of low permeability oilfield has the advantages of irreplaceable water drive,which can reduce the interfacial tension,reduce the viscosity of crude oil,improve the oil displacement efficiency and the fluctuation volume,and can greatly improve the oil recovery rate.The domestic and foreign oil field test has made remarkable effect.This text based on the basic situation of B-block,the indoor simulation experiment was carried out,and the mechanism of CO₂ flooding was studied by expansion experiment.In view of the actual situation of B block,the laboratory experiment,water/CO₂ injection,water/CO₂ alternation CO₂ flooding,CO₂ throughput and intermittent CO₂ injection.The optimal CO₂ injection method was selected to compare the final recovery rate,gas production ratio,oil change rate,water content and injection capacity,which laid the foundation for the CO₂ flooding pilot test of this oilfield,which is of great significance to the improvement of low permeability reservoir and the improvement of oil recovery.