塔里木盆地玉科区带石炭系膏盐岩地层套管变形原因分析及应用

Cause Analysis of Casing Deformation of Carboniferous Gypsum Salt Rock Formation in Yuke Zone of Tarim Basin and Countermeasures

通过地应力突变、膏盐岩蠕变、固井质量等多因素分析,确定塔里木盆地塔北玉科区带石炭系膏盐岩地层套管变形主要原因为在岩性界面岩石力学参数差异导致剪切错动;区域上发育的膏盐岩互层发生蠕变,从而致使套管严重变形;已完钻井固井质量较差也使得套管外受力不均匀而产生变形。提出了将区域上原来使用的2层套管结构优化为3层;将石炭系膏盐岩地层封固之后再进行下步钻进;适当提高套管抗外挤强度。解决了区域上的石炭系膏盐岩段套管严重损坏问题,确保顺利钻进,为后期作业提供了井筒条件保障。

Through the analysis of crustal stress mutation, gypsum salt rock creep and cementing quality, it is held that the main causes of the casing deformation are the difference of rock mechanical parameters in lithologic interface leading to shear dislocation, the creep of the regional developed gypsum salt rock layers resulting in the serious deformation of the casing, and the poor well cementing quality leading to the uneven stress and deformation of the casing. The countermeasures are proposed： changing the original two-layer casing structure into three-layer structure; cementing the Carboniferous gypsum salt rock formation and then drilling lower formation; appropri- ately increasing casing strength. The above measures can solve the problem of serious damage to the casing of the Carboniferous gypsum salt rock in the area, and ensure the smooth drilling, and provide good wellbore condition for the later work.