Influencing Factors of CO2 Miscible Flooding in Low Permeability Reservoirs in Block X
In order to study the influencing factors of CO2 miscible flooding in low-permeability res-ervoirs in Block X,this paper conducts laboratory experiments to analyze the minimum miscible pressure of injected gas CO2 and formation fluid,and analyzes the contact time,permeability,heter-ogeneity,and impurity gas on CO2.The influence of miscible flooding provides a theoretical basis for CO2 injection in low-permeability reservoirs in Block X.The main conclusion of the experiment are as follows:the minimum miscible pressure of this block is 17 MPa determined by the thin tube ex-periment.The contact time,permeability and impurity gas will affect the effect of CO2 miscible flooding.The longer the contact time of CO2 and formation fluid is,the better the miscibility effect of CO2 and formation crude oil becomes.The effect of CO2 miscible flooding in low permeability reser-voirs is better than that in medium and high permeability reservoirs.Heterogeneity has less effect on miscibility.The CO2 miscible pressure increases with the increase of the mole fraction of N2 and CH4,and decreases with the increase of the mole fraction of C2 and C4.The purity of the injected gas CO2 should be above 95％.The above analysis provides a theoretical basis for subsequent CO2 injection miscible flooding in the target block.
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