Research and Tests on the Technology of Releasing and Fishing Stuck Throttles Under Pressure

Abstract In order to solve the problem of gas well shutdown caused by fishing failure due to stuck throttles, and to avoid situations such as the inability to lift the pipe string and high cost of handling stuck throttles, the basic structures of the slip-type throttles were analyzed. And based on the actual situation on site, it was determined that the deformation of the slip mechanism was the main cause of the throttles getting stuck. And combined with conventional bridge plug drilling and grinding, coiled tubing fishing, and steel wire fishing techniques, the technology of grinding and milling under pressure to release and fishing stuck throttles was studied. Theoretical analysis has been conducted on the feasibility of using coiled tubing mill to break the slip mechanism of the stuck throttles, including mill torque, construction displacement, drilling pressure, etc. At the same time, the technical principle and operation process of gas lift fishing throttles were introduced. Two three-packer string wells were successfully tested in the field. After the stuck throttles were milled and unblocked by the coiled tubing, the stuck throttles of Φ73.0 mm tubing were successfully salvaged, one of which was fished by gas lift. The average construction time is less than 2.5 days. The research results show that the technology of grinding and milling with pressure to release and fishing stuck throttles is safe and efficient, providing a new technical means for dealing with stuck throttles and has good promotion and application value.