定向钻杆接头螺纹胀扣失效分析

Failure analysis of expansion for joint thread in directional drill pipe

钻杆接头内螺纹胀扣失效问题严重制约了钻孔效率,并导致了大量的经济损失。为了揭示其失效的主要原因,基于非线性接触理论建立了定向钻杆三维有限元模型,对钻杆接头抗扭性能进行有限元分析;基于有限元分析结论开展钻杆胀扣试验,分析了转矩和钻杆内螺纹外径尺寸变化的关系。研究结果表明:转矩和弯矩的共同作用导致定向钻杆胀扣;当钻杆承受转矩时,弹性变形量应小于0.08mm。

The internal thread expansion at the drill pipe joint seriously restricts the drilling efficiency and leads to a large amount of economic loss.In order to reveal the main causes of the failure,a three-dimensional finite element model of the directional drill pipe was established based on the nonlinear contact theory,and the anti-torsional performance of the drill pipe joint was analyzed by finite element method.Then,based on the conclusion of the finite element analysis,a test for drill pipe expansion was conducted to analyze the relationship between torques and changes in the outer diameter of the drill pipe internal thread.The research results showed that the combined effect of torque and bending moment led to the expansion of the directional drill pipe.When the drill pipe was subjected to torque,the elastic deformation should be less than 0.08 mm.