套管径向变形可修复界限研究

Study of Minimum Repair Limit for Reduced Casing Deformation

由于缩径变形套管的最小可修复内径没有明确值,导致采用胀管器整形时容易造成套管二次伤害。在分析胀管器冲击整形作用机理的基础上,根据缩径变形套管的整形工艺,利用ANSYS/LS-DYNA动力有限元程序编制了确定缩径变形套管可修复最小内径的计算程序。以钢级P110、139.7mm不同壁厚套管为例,计算了不同缩径量下的最小修复内径,并根据计算结果绘制了缩径套管内径与胀管器规格对应图版。对计算结果进行了评价分析,结果表明,采用高效胀管器修复缩径套管时,最小修复内径取决于套管的屈服强度和需要达到的最小通径,为了达到所需的最小通径,需要在最小修复内径基础上换3～4种规格的胀管器。在中原油田文95-86井的应用表明,根据计算出的最小修复内径修复缩径套管,可以在保证不伤害套管的前提下提高修复缩径套管的成功率。

Secondary damage to a casing often happen in casing repairing when using the expander be- cause minimum repairable inner diameter for reduced casing is not specified. A program for determining the minimum inner diameters of a diameter reduced casing was made by explicit dynamic ANSYS/LSDYNA finite element program based on the expander repair mechanism and casing repair technology. As an exam ple for 139.7 mm casing of steel grade Pl10, the minimum repairable inner diameter was caculated and a chart of expander sizes versus reduced casing inner diameters was provided. The research showed during the remedial operation, the minimum casing repairable diameter depends on the yield strength of the casing and its required minimum runthrough size. In order to obtain the required minimum runthrough size, it is necessary to change the expander size for 3 to 4 times. Its application in Wen 95-86 Well of Zhongyuan Oilfield showed the calculated minimum repairable inner diameter could improve the success rate of reduced casing repairment.