对某井进口φ339.7 mm 电阻焊(ERW)套管固井事故进行了全面调查研究,通过对磁性定位测井CCL曲线反映的套管柱失效形貌和对井下捞出的套管残片形貌进行分析认为, 套管柱在固井过程中发生了脱扣, 脱扣位置在第5根套管的工厂连接端。通过对套管的螺纹加工、材料和上扣连接质量等进行分析和对套管柱在固井过程中的受力状态进行计算认为, 套管所受载荷远小于其连接强度, 排除了过载导致套管脱扣的可能性, 认为套管接头是在固井期间首先松动之后才发生脱扣的; 套管接头在井下松动的原因是由于套管柱在固井过程中受到了很大的震动载荷; 套管接头从工厂上扣端松动脱扣的原因主要与工厂上扣扭矩偏小有关。

The well cementing accident in one well was comprehensively investigated and studied. It was found that the import casing string was pulled out from the 5th casing mill connection end during well cementing process by analyzing the CCL curve of magnetism orientation survey well and distinguishing casing remains fished out from the well down. The possibility that over load resulting in casing connection pulling out could be eliminated because the load borne on the casing connection was far less than its rated tension strength according to the test results and casing service condition. It was considered finally that the casing connection was unscrewed first due to jarring load borne on it during well cementing because it was not made up with enough torque in the mill, and then was pulled out by analyzing and calculating.