Influence of different injection methods of CO2 flooding on flow ca-pacity of low permeability reservoirs
CO2 flooding technology is an effective technical means to enhance the recovery of low permeability reservoirs.After CO2 comes into contact with crude oil,the asphaltene in the system is deposited in a solid form,which causes a certain blockage to the reservoir,but the dissolution improves the flow capacity of the reservoir as a whole at the same time.The damage of CO2 flood-ing to low permeability reservoirs under different injection methods is different.The organic scale plugging mechanism,reservoir wettability,and CO2-water solution corrosion evaluation experiments were carried out after continuous CO2 injection and CO2-water alternating injection.The variation characteristics of relative permeability curve parameters were evaluated,and the damage of dif-ferent injection methods of CO2 flooding to low permeability reservoirs was quantitatively characterized.The results show that the organic scale produced by CO2 flooding would block the pore throat of the rock,but on the whole,the dissolution caused by the re-action of CO2 and chlorite is stronger,which makes the recovery of the low permeability reservoirs effectively enhanced.More-over,the organic scale blockage caused by CO2-water alternating injection is weaker than that caused by continuous CO2 injection,and the dissolution effect is better.The permeability loss rate is lower.It could achieve a better oil displacement effect in pores with a radius of more than 0.2 μm and increase the pore space and flow channel of the rock so that the recovery of low permeability reser-voir could be effectively improved.
CO2 floodingCO2-water alternating injectionorganic scaledissolutionrelative permeability curveenhanced oil re-covery
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