基于钻柱动力学的井筒摩阻系数预测与应用

井筒摩阻系数是钻井设计和施工阶段准确预测和控制摩阻扭矩的关键因素，对比摩阻扭矩的实测值与预测值可预防钻井事故的发生。为此，基于钻柱动力学摩阻扭矩计算模型，结合近钻头多参数测量仪实测数据，开展了大斜度井实钻条件下套管段和裸眼段摩阻系数的预测方法研究，结果成功应用于同类型邻井的三开钻进阶段摩阻扭矩分析与控制。现场应用结果表明，实钻井筒套管内摩阻系数0.27~0.29，裸眼段摩阻系数0.39~0.41，均高于经验值；案例井钩载和扭矩预测值与实际值的误差满足施工精度要求，依托摩阻扭矩预测图版实时监测实钻摩阻扭矩的异常变化，保障了该井顺利施工。研究结果可为大斜度井钻机设备优选、井身剖面优化和现场钻井施工方案决策等提供科学依据。

Prediction and Application of the Shaft Friction Coefficient Based on Drill-string Dynamics

Accurate prediction and control of friction torque during the design and construction of drilling phases can prevent drilling accidents, and the shaft friction coefficient is a key factor in predicting friction torque. Therefore, we predicted the friction coefficients for the casing and open-hole sections for highly-deviated well drilling based on a calculation model for friction torque. This was based on drill-string dynamics and data from a near-bit, multi-parameter measuring instrument. The results were successfully applied to the analysis and control of friction torque in the third-spud drilling stage of adjacent wells of the same type. The field application results revealed that the friction coefficient of the actual drill casing was 0.27~0.29, and the friction coefficient of the open hole was 0.39~0.41, both of which are higher than the empirical values. The error between the predicted and actual values of the hook load and the torque of the case satisfied the construction accuracy requirements. The friction torque during actual drilling was monitored in real time to detect abnormal changes based on the friction torque prediction chart, which ensured smooth construction of the well. The results provide a scientific basis for optimizing drilling equipment and the well profile of highly deviated wells, and for planning the on-site drilling construction.