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用计算机对带扶正器的下部钻柱进行数值模拟得到了理论上和实践上有意义的结论。模拟结果可用于指导直井钻进和定向钻井。附求A给出了有限元法用于下部钻柱分析的基本公式。模拟程序用FORTRAN语言写成。采用人机问答方式把数据输入计算机。用户可选择输出列表数据或用宽行打字机绘制下部钻柱变形图。 计算机模拟结果指出仅用钻头侧向力不能反映下部钻柱性能。应采用钻头侧向力和合力角两顶指标才能综合下部钻柱性能。以合力角为基础分析了三大类钻柱组合——稳斜,造斜和降斜。用现场数据与模拟结果作了对比。模拟结果加上地层因素的分析可以预测井眼路径和指导选择合适钻柱组合和钻压。
Computer simulation of the lower drill string with centralizer results in both theoretical and practical significance. Simulation results can be used to guide both vertical well drilling and directional drilling. Annex A gives the basic formula for finite element analysis of the lower drill string. Simulation program written in FORTRAN language. The use of man-machine questions and answers into the computer data. The user can choose to export the list data or draw the lower drill string deformation with a wide-typewriter. Computer simulation results indicate that the use of bit lateral force alone does not reflect the behavior of the lower drill string. Should be used bit lateral force and co-force angle of the top two indicators in order to integrate the performance of the lower part of the drill string. Based on the resultant force angle, the author analyzed three major types of drill-string combinations: Steady-rise, Inclined-and-Down. The field data and simulation results are compared. Simulation results plus the analysis of the formation factors predict the wellbore path and guide the selection of appropriate drill string combinations and weight-on-bit.