Efficient injection-discharge-production integrated string in salt-cavern gas storages

Gas injection and brine discharge is an important procedure to realize cavity injection and production of salt-cavern underground gas storage. At present, domestic gas injection and brine discharge technologies have the problems of small open area of gas injection and brine discharge in the string, long brine discharge period, great risk of tripping out the brine discharge string under pressure and complex procedure. A new type of efficient injection-discharge-production integrated string was developed based on the field situations of Jintan salt-cavern underground gas storage. Then, its feasibility, timeliness, safety and economy were researched by means of downhole test. It is indicated that after the application of the efficient injection-discharge-production integrated string, average brine discharge rate is increased from 108.59 m³/h to 136.94 m³/h, brine discharge efficiency is increased by 26%, average gas injection and brine discharge time per well is shorted by 24 d from 115 d to 91 d. The release is adopted to discard the liner, so the procedure of tripping out the brine discharge pipe under the pressure is skipped, and thus the operation time is shorted by 10-15 d. This new type of efficient injection-discharge-production integrated string can improve the construction speed of salt-cavern underground gas storage effectively, diminish the safety risks and reduce the construction cost of salt-cavern underground gas storage, so it can be popularized in the construction process of salt-cavern underground gas storage.