非正常井眼对气体钻井下部钻具受力影响研究

提出了气体钻井中有井壁坍塌的非正常井眼下部钻具受力影响的研究，根据现场井眼坍塌形状，将该非正常井眼简化为椭圆截面的坍塌井眼，建立了下部钻具有限元分析的力学模型，开发了其有限元分析的ANSYS-APDL程序，可以方便地对钻具进行有限元力学分析。研究了4种非正常井眼情况下，下部钻具的受力情况，得到了钻具在坍塌井眼附近的变形位移、钻具弯矩、钻具内的应力分布大小以及钻头的偏转角等，为气体钻井坍塌井眼的井斜机理研究提供了研究方法和为其防斜打快提供了理论依据。

STUDY ON THE INFLUENCE OF ABNORMAL WELL BORE ON BOTTOM HOLE ASSEMBLY STRESS IN GAS DRILLING

The research on the influence of abnormal well bore on bottom hole assembly(BHA) in gas drilling with bore hole collapse is carried out，according to the shape of the collapse，the abnormal well bore is simplified into the collapsed hole with ellipse-shaped section，the mechanical model of finite element analysis for bottom hole is set up and the ANSYS-APDL programe is developed which can be used for analyzing finite mechanics of the assembly conveniently.The BHA stress is studied under the conditions of four types of abnormal well bores，the deformation displacement of the assembly adjacent the collapsed bore，assembly moment，the stress distribution inside the assembly and the deflexion angle of the bit are obtained，which provides the theoretical evidence for the well deviation mechanism of collapsed bore，preventing deviation and increasing drilling rate.