A characteristic of Fusselman gas wells in the Permian Basin is that they begin to produce connate water early in the life of the well. Eventually the water entering the wellbore cannot be unloaded because the hydraulic pressure of liquid fall back becomes greater than the reservoir pressure and the well ceases to flow. At this watered out and nonflow state, considerable gas may remain in the formation. This case study deals with the development of a closed loop gas lift system designed to unload water.

The gas lift system consists of: a predetermined number of gas lift valves externally mounted on mandrels and installed in the tubing string, surface processing equipment, and a gas compressor. Dewatering of the well is accomplished by injecting gas down the tubing-casing annulus and through the gas lift valves. The injection and dewatering process continues until the reservoir pressure overcomes the hydrostatic head. At this point the well will kick-off and flow. To maintain this flowing condition, a portion of the well stream is diverted and reinjected into the well to maintain high velocities in the tubing. The high tubing flow rate lifts the water and reduces the dynamic pressure gradient in the tubing.

The well in this study is currently producing in the above manner. Restoration of gas flow in this well required thirty days due to the uniqueness of the project and modifications through trial and error. Since then, the well has stabilized with a sales volume of 1,100 Mcf/D (31,500 m3/d) and gas lifts 350 barrels of water daily (55 m3/d). An injection volume of 400 Mcf/D (11,455 m3/d) maintains high tubing velocities and prevents the well from loading with water. An increase in reserves has resulted from gas lifting this nonproductive well.

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