Experimental research of condensate blockage and mitigating effect of gas injection

The condensate blockage causes a substantial decrease in well productivity for gas condensate reservoirs.Based on the previous studies,a novel experimental method was designed to evaluate condensate blockage and the mitigating effect of gas injection.The method considers the stacking effect in the near wellbore region and the gas flow in the far wellbore region.There is an intermediate vessel containing condensate gas at the entrance of core holder in the experimental apparatus.In the process of pressure depletion experiment in a long core model,the vessel is connected to the core and the pressure of the vessel remains above the dew point pressure.The seriousness of condensate blockage is investigated by this research.When pressure drops to maximum retrograde condensation pressure,the gas permeability decreases by 80%compared with the initial gas permeability.Contrastive experiments were conducted to study the removal effect of different injection fluids and different injection volumes.The results show that CO2 injection is more effective than methanol in mitigating condensate blockage and the optimal CO2 injection volume is around 0.15 HCPV。