Micro-hole coiled tubing sliding drilling tractor system structure design

Micro-hole coiled tubing(CT) sliding drilling can improve development benefit and cost cutting for the maturing field, shale gas, coal seam gas, tight gas and other unconventional gas reservoirs. It can reduce reservoir pollution, protect the environment and have a wide application prospects in China. However its wellbore diameter is very small, the CT drill string cannot revolute in the tiny wellbore, friction resistance of CT sliding drilling is so seriously that it is difficulty to run back into the well. The drilling weight can’t apply and even happen to sticking accidents. This has directly influenced the application and popularization of micro-hole CT sliding drilling technology. According to the present research situation of tractor at home and abroad, a kind of micro-hole CT sliding drilling tractor by electronic controlled hydraulic drive is designed. The tractor mainly includes a top slips support and traction system, a central sliding tube assembly, a control system and a bottom slip support system. The drilling fluid hydraulic energy drives its tractor by electronic control. The tractor is suitable for micro-hole underground work with good flexibility, good stability and strong flexible bending ability. The tractor can provide normal drilling fluid circulation, can realize two-way traction and power-off protection and make a trip for CT string. The difficult technical problems of CT sliding resistance will be solved for tripping CT string well by the tractor, which will promote the micro-hole CT sliding drilling technology development.