Research and Field Tests of Coiled Tubing Fishing Technology for Sand-Buried Throttles

In order to solve the problem of gas well shutdown caused by the failure of fishing sand-buried throttles, a sand-burial identification method for throttles in gas wells was proposed on the basis of the structural principle of slip-type throttles. Then the complicated reasons for fishing sand-buried throttles were analyzed. Combining the throttle treatments in conventional steel wire fishing and coiled tubing milling fishing as well as pulling tubing strings, the technical ideas and operational processes for coiled tubing sand washing and sand-buried throttle fishing were studied. After that, tool string for sand washing and fishing were recommended, and the theoretical minimum sand washing displacement corresponding to the coiled tubing and its diameter was analyzed. Field test of 4 horizontal wells showed that the sand-buried ϕ88.9 mm throttles were fished after sand washing, with a success rate of 100%, and an average total time of less than 1.5 days. The research results show that this technology for sand washing and fishing the sand-buried throttles is reliable, with a high success rate and a high popularization value in field applications.