套管尺寸偏差与挤毁强度关系的新认识  

New Understanding of the Relation between Casing Dimensional Variation and Collapse Resistance Strength

作　　者：张建兵[1] 刘歆[1] 吕祥鸿[2] 邓贺景 

机构地区：[1]西安石油大学机械工程学院,陕西西安710065 [2]西安石油大学材料科学与工程学院,陕西西安710065 [3]中国石油川庆钻探长庆钻井总公司,陕西西安710021

出　　处：《石油钻探技术》2010年第3期70-74,共5页Petroleum Drilling Techniques

基　　金：国家自然科学基金项目"石油套管膨胀后的强度及其力学机理研究"(编号:50704026);陕西省教育厅科技计划项目"膨胀套管技术主要力学参数计算研究"(编号:07JK369)资助

摘　　要：为了探讨API 5CT规范规定的套管尺寸公差对套管挤毁强度的影响,选取了J55钢级φ139.7 mm×7.72 mm、L80钢级φ177.8 mm×10.36 mm和P110钢级φ244.5 mm×13.84 mm 3种有代表性的油田常用套管,采用有限元法对其在不同外径和壁厚偏差影响下的套管挤毁强度进行了非线性分析、计算,得到了单独考虑外径、壁厚及同时考虑外径和壁厚尺寸偏差下的套管挤毁强度及其变化规律。计算可知,在API 5CT规范规定的尺寸公差范围内,即使套管外径和壁厚的最不利偏差同时出现在同一横截面上,套管的挤毁强度仍然会在API额定值之上,椭圆度对套管挤毁强度的影响大于壁厚不均度的影响,套管圆周上壁厚最薄点决定着套管挤毁强度,壁厚不均度对套管挤毁强度的影响非常小,API给出的大外径套管额定挤毁强度偏保守。对于尺寸公差符合API 5CT规范的套管,其挤毁强度一般会高于API额定值一定幅度。Three commonly used casings,J55 139.7 mm×7.72 mm,L80 177.8 mm×10.36 mm and P110 244.5 mm×13.84 mm were used to investigate the effect of casing dimensional variation on its collapse resistance performance.The effects of variant external diameter and wall thickness deviation on casing collapse resistance strength were analyzed using finite element method.The relationship between collapse resistance strength and external diameter and wall thickness deviation were obtained.Results show that casing collapse resistance performance is still qualified even if maximum permissible external diameter deviation and maximum permissible wall thickness deviation appear on the casing at the same time.The effect of out-of-roundness of casing on casing collapse resistance is higher than that of wall thickness nonuniformity.The collapse resistance strength of casing is determined mainly by the thinnest wall thickness in the circumference direction of casing.The collapse resistance strength value of casing with large external diameter given by API is conservative,and the actual collapse resistance strength of casing is greater than the rated strength value given by API 5C2 if the dimensional deviation of casing agrees with the API 5CT.

关 键 词：套管 偏差 抗压强度 有限元法 API标准 

分 类 号：TE931.2[石油与天然气工程—石油机械设备]