气体钻井井斜机理研究

Research on the Mechanism of Hole Deviation in Gas Drilling

气体钻井存在井斜不易控制的难题,其机理尚不明确。应用纵横弯曲BHA(底部钻具组合)分析方法和钻头与地层相互作用模型,根据实钻资料对比分析了气体钻井和钻井液钻井的地层造斜特性,进而探讨了气体钻井的井斜机理。结果表明,与钻井液钻井相比,气体钻井条件下地层造斜力和钻具降斜力都有增加,但地层造斜力增加的幅度更大,这正是气体钻井更容易发生井斜的原因。因此,建议在用气体钻井技术打直井段时,通过调整钻具组合和钻进参数适当增加钻具的降斜力,以提高井身质量。

Deviation control was difficult in gas drilling.The mechanism of hole deviation in gas drilling was not clarified.The comparative analysis between the deflecting characteristics of formation in gas drilling and mud drilling was carried out by means of BHA(Bottom Hole Assembly) analysis method and rock-bit interaction model.The result shows that formation deflecting force and bit side force in gas drilling are both bigger than that of mud drilling.But the difference of formation deflecting force between gas drilling and mud drilling is bigger than that of bit side force.Therefore,the main reason of the gas drilling has more deviation tendency than that of mud drilling.Therefore,in the gas drilling technique for vertical hole section,bit side force should be enhanced properly by means of selecting BHA and the adjustment of drilling parameter to improve wellbore quality.