成形温度对等井径膨胀套管螺纹接头强度的影响

Effect of forming temperature on strength of monohole expandable tubular with thread connection

实现井眼等直径钻井是膨胀管技术的终极目标,而套管之间的螺纹连接处为其膨胀成形过程中最危险的部位,应重点关注。以孪生诱发塑性(TWIP)钢为研究对象,利用有限元软件ABAQUS模拟了不同温度下螺纹接头的膨胀成形过程,分析了成形过程中膨胀力、Mises应力和三向应力的演化情况,并对成形后螺纹接头的残余应力做出了分析。结果表明,随着温度的增加,螺纹接头所需膨胀力逐渐减小;螺纹接头成形过程中径向应力和轴向应力以压应力为主,环向应力以拉应力为主;螺纹接头成形过程中以及成形后,随着温度增加,Mises应力峰值与抗拉强度之差逐渐变小,螺纹接头越容易失效。

Drilling with no diameter loss is the ultimate goal of expandable tubular technology. The thread connection between tubulars is the most dangerous part during expansion process which should be paid more attention. Using finite element software ABAQUS, the ex- pansion process of thread connection made of twinning - induced plasticity steel under different temperatures was simulated. The expansion force, triaxial stress and Mises stress during expansion process were investigated, and the residual stress of thread connection ＇after expan- sion process was also studied. The results show that the expansion force decreases with the increasing temperature; the radial stress and axial stress in the thread connection are donminated by compressive stress while the hoop stress is dominated by tensile stress; as the in- crease of temperature, the difference between peak value of Mises stress and ultimate tensile strength decreases during and after expansion process, and the thread connection is prone to be failure.