超高强度套管TP165V开发及蠕变应力分析

Development and Creep Stress Analysis of Super High Strength TP165V Casing

针对蠕变地层用套管套损问题,设计开发一种新型超高强度套管,套管钢级达到165 ksi,横向冲击值不低于55 J,纵向冲击值不低于70 J,套管抗挤毁强度超过182 MPa。采用有限元方法分析套管受到的蠕变应力和弹性应力。试验表明套管极限抗挤毁强度超过200 MPa;以中原油田产层最大地应力约50 MPa为例,套管实际抗挤毁强度达到最大地层压力4倍。研究发现套管弹性应力和蠕变应力随着两向地应力差异增加而增加,且蠕变应力增加幅度高于弹性应力;当盐膏层被溶解产生孔洞后,胶结面处应力先增加后减小,最后趋于稳定。

Addressing the problem of damage of the casing serving in the creep formation,a new type of ultra-high strength casing is designed and developed featuring the steel grade up to 165 ksi,the transverse impact value at least 55 J,the longitudinal impact value at least 70 J,and the collapse resistance strength exceeding 182 MPa.The creep stress and elastic stress of the casing are analyzed by finite element method.It is found via the test that the ultimate collapse strength of the casing exceeds 200 MPa.Taking the maximum in-situ stress of the production layer of Zhongyuan Oil Field as an example,the actual collapse strength of the casing reaches 4 times of the maximum formation pressure.Furthermore it is revealed via relevant the study that the elastic stress and creep stress of the casing increase along with the increase of the difference between the two-dimensional in-situ stresses,and the creep stress increases more than the elastic stress.When the salt layer dissolves and produces voids,the stress at the cementation surface increases first,then decreases,and finally tends to be stable.