The Research and Application of a Key Tool for Coiled Tubing Fishing with Coiled Tubing

In view of the low efficiency, high risk and high labor intensity of coiled tubing fishing with a conventional tubing string, research was conducted to investigate the current status of coiled tubing operation technologies. The process of coiled tubing fishing with coiled tubing was proposed, and a specific tool was developed. By virtue of its modular design, the tool was able to integrate the functions of fish top rotation entrance, fish top detection, fish top capture and shearing into the tool, so that the tool could adapt to the operation conditions of coiled tubing fishing. The results of simulation calculation and laboratory test verified that the performance of this tool met the desired design requirements. This fishing tool was used in Well X–1 of Tarim Oilfield on coiled tubing, and it finished 13 fishing jobs in ϕ88.9 mm production string. In total 2 851.87 m of ϕ38.1 mm coiled tubing that had been seriously stuck in the hole was retrieved, and the retrieval rate was up to 100%, while the fishing efficiency was four times higher than that of the conventional fishing string. The field application also verified the stability of tool’s performance. Studies suggested that this coiled tubing fishing tool could also be effectively applied in coiled tubing fishing, and it could provide technical references in the future for fishing in coiled tubing.