关于钻头轨迹形成的理论探讨

Inquiry on the Formation of Bit Trajectory

指出了现行钻头轨迹形成理论的差异之处，论述了下部钻具组合的弯曲形状对钻头钻进方向的影响，研究了下部钻具组合的弯曲形状、钻头侧向力、钻头转角等力学因素对钻头轨迹形成的影响，推导了钻头在三维各向异性地层中钻进轨迹的曲率增量表达式，模拟了平衡曲率钻进过程的基本特征。实例分析表明，用平衡曲率法预测下部钻具组合的造（降）斜特性较为准确。用本文提出的方法还模拟计算了实钻井眼轨迹，计算结果和实测吻合较好。

The paper points out the controdictory among the present standpoints on the formation of bittrajectory. It disscusses the effects of the flexibleshape of BHA on the bit trajectory. It researches theeffects of such mechanic factors as the flexible shape ofBHA, laterial force on bit and deviation of bit. It reduces the increment formula of well curvature whilebit drilling in anisotropic formation in 3-D case andthese formula is used in algorithm of prediction andsimulation of well path. The simulation of well pathdemonstrates the nature of equilibrium curvaturedrilling and effects of anisotropy, WOB and gap between stabilizer and well wall on equilibrium curvature. The actural example shows that using equildingum curvature can make correct prediction of building/dropping performance of BHAs. Also, an actural wellpath is simulated. Simulation results are coincidedwith actural survey. The computation of all examplesshows that equilibrium curvature has good practicalityin prediction.