PRODUCTION ENHANCEMENT IN GAS/CONDENSATE RESERVOIRS BY ALTERING WETTABILITY TO GAS WETNESS: FIELD APPLICATION

Liquid condensation in the rock near wellbore may kill gas production in gas condensate reservoirs when pressure drops lower than the dew point. It has been proved both theoretically and experimentally that gas production in gas condensate reservoirs can be improved by altering wettability of rock near wellbore from liquid wetness to gas wetness. However, to our best knowledge, no field tests have been reported. In this study, a pilot test was designed based on experimental results measured in the rock sampled from the target gas condensate reservoir. Experimental results demonstrated that the relative permeabilities of gas phase were increased significantly after the wettability was altered to gas wet. The residual water saturation was also decreased and the gas production was enhanced greatly due to the wettability alteration to gas wet. The gas condensate field, located in central China, is a high temperature and low permeability reservoir with a permeability of about 0.1 md. About 30,000 litters of chemical solution were injected into a well in the gas condensate field. Experimental results demonstrated that the chemical solution could change the wettability of the rock from liquid wetness to gas wetness. Gas production was resumed after the well was soaked with the chemical solution for about 48 hours. The test results showed that the gas production of the well was increased over 200%.