为了合理降低油气井套管成本,在CO₂腐蚀环境中使用3Cr钢+13Cr钢复合套管的设计方法,该方法以全井筒温度和CO₂分压剖面作为套管选材设计依据,对全井筒套管材料进行精细化设计,在腐蚀程度轻的井段使用3Cr钢套管,并对3Cr钢套管进行腐蚀速率预测及腐蚀后的套管强度校核,以提高复合套管选材的安全性,从而降低套管成本。目前复合套管设计方法在南海西部油田钻完井作业油套管选材中得到普遍应用,较传统套管选材方法可实现平均单井管材费用降低超100万元。

In order to reasonably reduce the casing cost of oil and gas wells, the design method of 3Cr steel + 13Cr steel composite casing was used in CO₂ corrosion environment. In this method, the whole wellbore temperature and CO₂ partial pressure profile are used as the basis for casing material selection design, and the whole wellbore casing material is finely designed. The 3Cr steel casing is used in the well section with light corrosion degree, and the corrosion rate of 3Cr steel casing is predicted and the casing strength after corrosion is checked, so as to improve the safety of composite casing material selection and reduce the casing cost. At present, the composite casing design method is widely used in the selection of oil casing materials for drilling and completion operations in the western South China Sea oilfield. Compared with the traditional casing material selection method, the average single well pipe material cost can be reduced by more than 1 million yuan.