铝合金钻杆强度的模拟仿真分析

与传统的钢制钻杆相比,铝合金钻杆具有密度小、比强度高、无磁等优点,因此在钻井作业中具有较大优势。钻杆在井下工作环境恶劣,如与井壁发生碰撞,将导致钻杆变形,降低其强度。笔者通过Ansys LS-DYNA以及Workbench进行仿真,研究Φ147 mm铝合金钻杆与孔壁碰撞后的变形状态,以及产生裂纹后对其强度进行分析。结果表明,Φ147 mm铝合金钻杆在使用过程中,钻杆主体段相对薄弱,在2 m/s的速度下与钻孔壁发生碰撞会产生塑性变形,从而降低铝合金钻杆的性能。钻杆主体段的裂纹长度1 mm时,在载荷作用下,将发生裂纹扩展,导致钻杆断裂。钻杆主体段有裂纹时,在疲劳载荷作用下,有裂纹的钻杆所能承受的载荷是无裂纹钻杆所能承受载荷的五分之一。

Simulation analysis of strength of aluminum alloy drilling pipe

Compared with the traditional steel drilling pipe, aluminum alloy drilling pipe is characterized by small density, high specific strength and no magnetism, so it has a great advantage in drilling operation. The tough underground working environment, such as the collision with the borehole wall, will lead to the deformation of the drilling pipe and reduce its strength. In this paper, Ansys LS-DYNA and Workbench were used to simulate the deformation state of the Φ147 mm aluminum alloy drilling pipe after the collision with the borehole wall, and the strength after the cracks were generated was also analyzed. The results show that when the Φ 147 mm aluminum alloy pipe is being used, the main section of drilling pipe is relatively weak and undergoes plastic deformation when colliding with borehole wall at a speed of 2 m/s, which reduces the performance of the aluminum alloy pipe. When the crack length of the main part of the drilling pipe is greater than 1 mm, the crack propagation will occur under the load, resulting in the fracturing of the drilling pipe. When the main body of the drilling pipe has a crack, under fatigue load, it can only bear one fifth of the load of the non-cracking drilling pipe.