大张坨储气库井油套管腐蚀规律分析

为了检测评价大张坨地下储气库注采井的技术状况及油套管实际腐蚀情况，利用多层管柱电磁探伤技术，对注采井油套管进行了探伤检测，分别获得油套管壁厚数据，并对油套管剩余壁厚、腐蚀速率进行了进一步的统计分析。研究结果表明，油套管腐蚀速率与注采井设计前的室内实验、生产过程的挂片监测试验数据相比有较大差异；油套管实际腐蚀量随井深增加而增加，环空保护液、水泥环界面附近及井口段腐蚀量显著增加。建议在储气库注采井油套管设计时，盈余量应显著大于常规油气井，特别是井口200 m段及下部位置。储气库注采井应在完成建井或注采井服役5 a内进行油套管基准壁厚的检测。

Analysis on the corrosion laws of the tubing and casing in the wells of Dazhangtuo Underground Gas Storage

In order to detect and evaluate the technical situations and actual tubing and casing corrosion situations of the injection and production wells in Dazhangtuo Underground Gas Storage, defect detection was carried out on the tubing and casing of injection and production wells by means of the electromagnetic inspection technology of multi-layer pipe string, and accordingly the wall thickness of tubing and casing were obtained. In addition, statistical analysis was further performed on the residual wall thickness and corrosion rate of tubing and casing. The research results show that the corrosion rate of tubing and casing are more different from the laboratory experimental data before the design of injection and production well and the coupon monitoring test data in the process of the production. What’s more, the actual corrosion of tubing and casing increase with the increase of well depth and the corrosion near the annulus protection fluid and the cement sheath interface and at the wellhead section increases greatly. When the tubing and casing of injection and production wells for gas storage are designed, it is recommended to set the surplus much higher than that of conventional oil and gas wells, especially the ones at the wellhead 200 m section and the lower part. And the reference wall thickness of tubing and casing of injection and production wells for gas storage shall be detected when the well is completed or its service period is within 5 a.