New Process of Water Drainage for Shale Gas Recovery

In order to ensure continuous production of shale gas wells both in high and low liquid content period,and to overcome the defects of drainage gas recovery lifting process,water drainage and gas recovery with concentric double tubing has been developed for shale gas wells.Because velocity string can reduce the critical flow rate to carry liquid so as to increase gas flow rate in the wellbore and improve liquid carrying capability of gas wells,the velocity string diameter in shale gas wells is optimized at φ48.3 mm;high capacity electric submersible pump is used in early production stage when gas flow rate is high,and gas lift is used to induce production when the gas flow rate is low.The technique has been tested in Well Pengye HF-1,the water drainage and gas recovery well produced 37 m3/d of liquid,20 250.65 m3/d of gas,and cumulative gas 151.32 ×104 m3 after the measures are implemented.The test results show that the water drainage and gas recovery with concentric double tubing can reduce the critical gas flow rate for liquid carrying,providing a new technical means for continuous production of shale gas wells.