Development of Downhole String Melting Cutting Tool
Currently,the disposal of malignant downhole stuck string is inefficient and time-consuming,which may cause additional damage to the wellbore and has become the main factor restricting the efficiency and safety of downhole operations.Therefore,a rapid cutting unfreezing tool for metal string based on high-temperature melting was developed.After the tool was lowered to the target depth,an anchoring mechanism was used to achieve a relative fixation of the tool and the cut strings,and the electricity was use to excite the purpose-made high-energy thermite grain.The thermite rapidly reacted and released a large amount of ultra-high temperature plasma flame.The flame was ejected radially at high speed under the guidance of a specially designed jet mechanism and imple-mented radial melting cutting on the string.Moreover,a melting cutting test of ø127 mm heavy wall drill pipe was carried out in a liquid environment to verify the feasibility of downhole operation of the tool.The research results show that the anchoring mechanism can successfully complete the relative fixation of the tool and the cut strings,the thermite can be successfully excited,and the jet mechanism can guide the flame to eject at high speed and imple-ment radial melting cutting.The melting cutting depth of the strings are related to the thermite load,and the tool can perform melting cutting operation on different thickness of strings.At a thermite load of 10 kg,the average cut-ting depth reaches 21 mm after 8 s of cutting.The tool and its technology provide a new solution for efficient and safe unfreezing of downhole stuck strings.
downhole stringstring stuckmelting cutting toolflow jettingthermitecontrol system
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