DN2-12井不锈钢油管酸化作业后粘扣及腐蚀原因分析

DN2-12井经过两次酸化作业之后,其不锈钢油管接头发生了严重的粘扣和腐蚀。对该井的两次酸化测试作业情况进行了调查研究,对经过酸化作业起出后的油管进行了检测分析,发现大多数油管粘扣,部分油管腐蚀。通过对油管粘扣形貌和分布规律进行宏观分析和统计分析,认为油管粘扣的主要原因是对扣和引扣操作不当所致;通过模拟腐蚀试验和对油管腐蚀形貌进行分析,认为油管接头部位存在腐蚀集中,而腐蚀集中与接头结构设计和加工精度有关;另油管腐蚀还与酸化液中的腐蚀介质和天然气中的CO2含量有关,也与油管结构和受力状态有关。

Cause Analysis on Galling and Corrosion of Stainless Steel Tubings in Well DN2-12 after Acidification

The stainless steel tubings had serious galling and corrosion after two times of acidification operation in well DN2-12. A thorough investigation on two times of acidification operation in the well was carried out, and found that most tubings galling and part tubings corrosion by inspecting the tubings after acidification. It is considered that the tubings galling was caused by improper operation per macro analysis on galling morphology and statistic analysis on galling position. It is thought that there was corrosion concentration at the tubings joints that was related to joint design and machining precision by analyzing corrosion morphology. Tubings corrosion was related to the corrosion medium in the acidification liquid and CO2 in the well gas, as well as the stress state.