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在丛式钻井设计中，下部钻具组合性能分析、井眼轨道控制和预测都是十分重要的技术问题，而要解决这些问题必须对下部钻具组合进行受力变形分析。本文根据丛式钻井中钻柱的实际工作状态，选取口至井底的整个钻柱为研究对象，充分考虑各种因素，首先建立了整体钻柱静力分析模型，然后根据整体钻柱的受力变形分析值，建立了修正的下部钻具组合静力分析模型。该模型与以往一些下部钻柱静力分析模型相比，简化少，考虑因素多，钻头处的变

FOUNDATION OF A MODEL FOR ANALYZING DRILLING STRING BY THREE-DIMENTION STATIC FORCE IN MULTIPLE WELLS

It is important for multiple drilling of analyzing the performance of bottom hole assembly (BHA)and controlling & foretelling the trajectory of wellbore hole; To solve these problems,the deformation of BHA by force must be analyzed. In actual work state of drill string in multiple drilling,selecting the drill stem from top to bottom as target, considering all the factors, this paper sets up a model for analyzing the whole drill stem by static force.As the result of its value.the modified model for analyzing BHA by static force is set up. Compared with other models, this model is overall. The values of three forces of variable inclination, variable direction and journal corner are reasonable for analyzing the performance of BHA,controlling and foretelling the trajectory of the wellbore hole. Interstice element method is utilized to analyze and compute the interstice between a stablizer and well wall closed by a bit. The affection of wellbore hole with BHA on variable inclination and variable direction is good for simplizing the model.