EVALUATION ON PHASE - STATE MECHANISM OF GAS CONDENSATE WELL CONSIDERING FORMATION WATER BY CO_2 INJECTION

In order to evaluate the phase-state mechanism of CO2 Injection to eliminate retrograde condensate pollution of the near borehole zones for gas condensate well considering formation water,based on the three phase equilibrium thermodynamic theory,PR state equation,HV mixed rule and activity coefficient model,the CO2 hydrocarbon-water phase equilibrium thermodynamic calculation model and evaluation method have been established.With the model and method,the phase-state mechanism of CO2 Injection is evaluated for a real gas condensate well considering formation water.The effects of the CO2 injection time on retrograde condensed liquid saturation,recovery curve and the CO2 injection volume on retrograde condensed liquid saturation,recovery,dew point pressure,condensed liquid reserve are studied.Research results show that: the CO2 injection is more effective when it performed before the maximum retrograde condensation pressure;the more the injected volume is,the better the result is;While CO2 are injected in different injection times,the condensed liquid recovery curve will intersect,and the retrograde condensed liquid volume and the dew point pressure will decline;While CO2 are injected with the same volume,the condensed liquid reserve will increase as the injection time is delayed.