Zhang Yu, Shu Jiangjun
China Coal Technology and Engineering Group, Chongqing Research Institute, Chongqing, China.
State key Laboratory of Coal Mine Disaster Prevention and Control, Chongqing, China.
Heliyon. 2024 Sep 26;10(19):e38314. doi: 10.1016/j.heliyon.2024.e38314. eCollection 2024 Oct 15.
Directional drill pipes are prone to failure in the fish-bone branch wells. The primary cause of the directional drill pipes failure is excessive bending. This paper established a mathematical analysis model for the bending stress of the directional drill pipes at any point along its trajectory. Tested the mechanical properties of the directional drill pipe. An ultimate bending experiment was conducted on the directional drill pipes based on the pure bending moment theory. Additionally, a non-linear finite element model(FEM) of the directional drill pipes was established to analyze the influence of different bending loads on the stress distribution of the directional drill pipes connection. The FEM results were consistent with the results of the ultimate bending experiment. The FEM results indicate that the Box bending under transverse force is the primary cause of the failure for the Tooth top. The research results enable engineers and operators to easily obtain the stress distribution of the directional drill pipes under borehole curvature.
定向钻杆在鱼骨分支井中容易失效。定向钻杆失效的主要原因是过度弯曲。本文建立了定向钻杆沿其轨迹任意点弯曲应力的数学分析模型。测试了定向钻杆的力学性能。基于纯弯矩理论对定向钻杆进行了极限弯曲试验。此外，建立了定向钻杆的非线性有限元模型（FEM），以分析不同弯曲载荷对定向钻杆接头应力分布的影响。有限元模型结果与极限弯曲试验结果一致。有限元模型结果表明，横向力作用下的钻杆本体弯曲是钻杆接头失效的主要原因。研究结果使工程师和操作人员能够轻松获得定向钻杆在井眼曲率下的应力分布。
