套管压裂管柱安全性计算方法与准确性研究

通过对新疆油田公司5井次套管压裂事故的套管柱进行安全性计算,发现基于静态受力分析的管柱安全性计算方法在直井中有着较高的准确性,能够保证套管柱的安全。对于水平井,该方法的计算结果与实际不符,不能指导压裂作业。分析理论极限泵压与油层套管实际破坏泵压的误差,该误差值与水平段长度呈正比关系。在水平井中采用该方法计算压裂管柱的安全压力时,应当根据水平段长度设定安全系数。根据统计结果,在水平段长度为1600 m时,油层套管的三轴应力安全系数应当增加16.27%。

Study on Calculation Method and Accuracy of Casing Fracturing String Safety

Through the safety calculation of the casing string in the 5th casing fracturing accident of Xinjiang Oilfield Company, it is found that the calculation method of the string safety based on the static force analysis has high accuracy in the vertical well and can guarantee the casing string Security. For horizontal wells, the calculation results of this method are inconsistent with reality and cannot guide the fracturing operation. By analyzing the error between the theoretical limit pump pressure and the actual destruction pump pressure of the oil layer casing, it is found that the error value is proportional to the length of the horizontal section. When this method is used to calculate the safety pressure of a fracturing string in a horizontal well, the safety factor should be set according to the length of the horizontal section. According to statistical results, the triaxial stress safety factor of the oil layer casing should increase by 16.27% when the length of the horizontal section is 1 600 m.