用数理统计方法预测油套管腐蚀剩余寿命

Using mathematical statistics method to predict remaining life of corroded tubing and casing

马晓勇 翟晓鹏 张艺馨 马树泉 郭毅 姬辉 李永兵

长江大学油气钻采工程湖北省重点实验室，湖北 武汉 430100 长江大学石油工程学院，湖北 武汉 430100 长江大学地球环境与水资源学院，
湖北 武汉 430100 中国石化胜利油田分公司黄河钻井三公司，山东 东营 257091 中国石油长城钻探工程有限公司压裂分公司，辽宁 盘锦 124010 中海油田服务股份有限公司油田生产事业部，天津 300450 中国石化西北油田分公司采油一厂，新疆 库尔勒 841600

在稠油开采过程中，由CO2腐蚀造成的油套管损坏事故频繁发生，有必要对油套管进行可靠性评估和剩余寿命预测。文中分析了油套管腐蚀机理和规律，研究了腐蚀概率分布规律；通过长效实验，结合室内加速腐蚀实验数据，运用数理统计方法预测了腐蚀发展规律；通过预测油套管剩余强度和安全系数可以预知套管的剩余寿命。预测结果与实际情况接近，证实了油气井套管CO2腐蚀符合指数概率分布类型。以概率统计预测的腐蚀速率为依据，结合套管强度设计方法，可以有效预测油套管剩余寿命。

The tubing and casing damages caused by CO2 erosion have become more and more serious during the heavy oil production, so the reliability evaluation of tubing and casing and the prediction of remaining life must be done. This paper analyses the mechanism and law of tubing and casing erosion, and it also studies the probability distribution rule. It also predicts erosion developing law using mathematical statistics method. Through predicting the remaining strength and safety factor of tubing and casing, the remaining life of oil casing may be predicted. The results are more close to practical situation by this method and prove CO2 corrosion of oil and gas well casings to conform to the type of probability distribution, but more in line with exponential probability distribution type. Based on the probability statistical prediction of corrosion rate and combined with the method of casing strength design, the remaining life of oil casing can effectively be predicted.

10.6056/dkyqt201304027