煤矿井下小直径旋转导向工具造斜能力影响因素分析OA

[Objective]Intelligent drilling represents an important part of intelligent coal mine construction.However,measurement-while-drilling(MWD)directional drilling,the core of underground intelligent drilling operations,cur-rently suffers from several limitations,including the high dogleg severity of wellbore trajectories,low drilling efficiency,and poor hard-rock penetration.Rotary steerable system(RSS)technology has emerged as a key approach to addressing these limitations owing to its high-precision control on drilling trajectories.[Methods]This study systematically ana-lyzed the factors influencing the build-up rate of small-diameter,push-the-bit RSSs using a modified 3-point circle meth-od and the longitudinal beam bending method.Through theoretical modeling,the coupled impacts of various parameters on the build-up rate of the RSSs were quantified,including:(1)structural parameters,i.e.,the distance from the drill bit to the lower stabilizer(L1),the distance from the drill bit to steering pads(L0),and the dimensions of steering pads;(2)drilling parameters,namely,the steering force and weight on bit(WOB);(3)and formation parameters,i.e.,rock hard-ness,formation anisotropy,and formation homogeneity.Accordingly,the configuration and structural parameters of the rotary steerable bottom hole assembly(BHA)were optimized to support high-precision trajectory control of directional boreholes in underground coal mines.Lastly,the performance of the optimized BHA was verified through surface drilling experiments.[Results and Conclusions]For surface drilling experiments,a near-horizontal borehole was drilled using trajectory control modes,including magnetic guidance and stable inclination control.By applying collaborative op-timization measures,including shortening the L1 to the appropriate range,increasing the thickness of steering pads,adding an additional stabilizer,and maintaining low WOB,build-up rates of up to 18°/hm to 20°/hm were achieved dur-ing surface drilling experiments.Compared to underground industrial experiments,the optimized small-diameter push-the-bit RSS increased the build-up rate by 40％and significantly enhanced trajectory control precision,thus effectively addressing the limitations of conventional directional drilling.The proposed strategy of the collaborative optimization of structural parameters,drilling parameters,and formation characteristics provides critical technical support for construct-ing high-precision transparent mining faces in underground coal mines,thereby advancing intelligent drilling techno-logy toward high precision and efficiency.