<p>The utilization of measurement while drilling (MWD) technology for investigating the geological information of strata, to guide the support design in coal mine roadways, is increasingly emerging as a prevailing trend. However, the distortion of drilling parameters caused by the buckling of drill rod significantly impedes the accuracy of MWD technology. Therefore, this study established an analytical model of sinusoidal buckling for restricted slender drill rod, analyzed the change law of contact friction under the coupling effect of axial loads and drill rod length, and revealed the effect of buckling on distortion characteristics of drilling parameters. Finally, a method for correcting drilling parameters in applications of MWD technology was proposed. The research indicates that during the application of MWD technology at drilling depths between 3.0 and 10.0&#xa0;m, sinusoidal buckling occurs in the drill rod with orders ranging from 2nd to 5th. Moreover, within this range, thrust ranges between 1.9 and 15.6 kN can be expressed by the boundary equation: 0.27<i>R</i><sub>c</sub>-3.73 ≤ <i>F</i> ≤ 0.37<i>R</i><sub>c</sub>-2.96. Within this depth range for MWD technology application, contact friction ranging from 0.1 to 0.6 kN are observed. The loss distribution ranges are notably 0.5 kN ~ 3.5 kN, 0.5 N∙m ~ 4.5 N∙m, and 150 W ~ 750 W for thrust, torque, and power, respectively. The losses of drilling parameters can be categorized into three distinct zones, and the boundaries’ equations defining each loss zone are delineated. The buckling model in this study is mainly aimed at the drill rods of anchor holes construction in coal mines. Such drill rods and boreholes are much simpler than the drill string and wellbore in oil and gas drilling, which leads to the lower accuracy of the buckling model in this paper in the application of large-diameter drill pipes such as oil and gas drilling. This study has important value for reducing the distortion of drilling parameters and improving the accuracy of MWD technology.</p>

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Mechanism of Drilling Parameter Distortion Induced by Drill Rod Buckling While MWD Application

  • Sun Xin,
  • Cheng Jingyi,
  • Zhang Xianxin,
  • Wan Zhijun,
  • Lian Yadong,
  • Liu Kechen

摘要

The utilization of measurement while drilling (MWD) technology for investigating the geological information of strata, to guide the support design in coal mine roadways, is increasingly emerging as a prevailing trend. However, the distortion of drilling parameters caused by the buckling of drill rod significantly impedes the accuracy of MWD technology. Therefore, this study established an analytical model of sinusoidal buckling for restricted slender drill rod, analyzed the change law of contact friction under the coupling effect of axial loads and drill rod length, and revealed the effect of buckling on distortion characteristics of drilling parameters. Finally, a method for correcting drilling parameters in applications of MWD technology was proposed. The research indicates that during the application of MWD technology at drilling depths between 3.0 and 10.0 m, sinusoidal buckling occurs in the drill rod with orders ranging from 2nd to 5th. Moreover, within this range, thrust ranges between 1.9 and 15.6 kN can be expressed by the boundary equation: 0.27Rc-3.73 ≤ F ≤ 0.37Rc-2.96. Within this depth range for MWD technology application, contact friction ranging from 0.1 to 0.6 kN are observed. The loss distribution ranges are notably 0.5 kN ~ 3.5 kN, 0.5 N∙m ~ 4.5 N∙m, and 150 W ~ 750 W for thrust, torque, and power, respectively. The losses of drilling parameters can be categorized into three distinct zones, and the boundaries’ equations defining each loss zone are delineated. The buckling model in this study is mainly aimed at the drill rods of anchor holes construction in coal mines. Such drill rods and boreholes are much simpler than the drill string and wellbore in oil and gas drilling, which leads to the lower accuracy of the buckling model in this paper in the application of large-diameter drill pipes such as oil and gas drilling. This study has important value for reducing the distortion of drilling parameters and improving the accuracy of MWD technology.