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在定向井、丛式井、水平井钻井中，对待钻井眼方位变化的预测，一直是个重要的问题，它直接影响到待钻井眼的设计，井下工具的准备、选择，影响到下部井段是否能顺利施工。为此，运用钻具力学分析和地层各向异性理论的研究成果，综合考虑上部井眼或邻井的实钻情况和地层产状要素等，利用钻具与岩层间的空间位置关系计算钻头的位移量，从而定量地推导出了待钻井眼方位变化率计算式，通过对川西南隆４０－１大斜度定向井的计算和川中莲池５０水平井的预测，其效果是满意的，与实钻情况相符。

FORECASTING THE AZIMUTHAL CHANGE RATE OF UNDRILLED BOREHOLE AND ITS APPLICATION

In the process of drilling directional well,cluster well and horizontal well,forecasting the azimuthal change of undrilled borehole is always an important problem,which directly influences the design of undrilled borehole,the preparation and selection of downhole tools,and whether a successful drilling operation will be done for the lower wellbore.For this ,by applying the results of drill string mechanics analysis and formation anisotropy theory study,and by comprehensively considering,the drilling practice of upper wellbore or adjacent well and the formation occurrence elements etc.,the displacement of bit is calculated by using the space position relation between drill string and strata,thus the formula for calculating the azimuthal change rate of undrilled borehole is quantitatively derived.Through the calculation of a high angle directional well-well Long-40-1 in southwest Sichuan and the forecast of horizontal well Lianchi-50 in central Sichuan,it is shown that the satisfying result conforms with drilling practice.