套管水泥环的室内破坏试验及力学分析

套管外水泥环的破坏是导致管外串槽、套管外腐蚀的原因之一。为弄清井下作业是否会损坏管外水泥环 ,进行了一系列室内破坏试验 ,并对试验结果进行了理论分析。试验结果表明 :管外水泥环无围压时 ,套管内施加很小的压力 ,就会导致水泥环上产生裂纹 ;水力锚作业对水泥环的破坏程度比压裂对水泥环的破坏程度更严重 ;没有围压的水泥环抗内压强度极低。提出压裂与酸化设计中 ,应考虑作业压力对套管外水泥环的破坏作用 ;在选用井下工具时 ,应尽量避免选用带有爪牙的局部支撑管柱的井下工具。

Lab test of destruction of cement sheath outside casing

Destruction of cement sheath outside casing is one of the causes for channeling and corrosion. To make clear if downhole operation will destroy the cement sheath, lab tests of cement sheath destruction are made, and the test results are analyzed. The results of the tests show that, when there is no confining pressure on the cement sheath, very small pressure from the casing may result in the occurance of cracks on the cement sheath; the destruction caused by hydraulic anchoring operation is more serious than that caused by fracturing; the cement sheath has very low anti inner pressure strength when there is no confining pressure. Therefore it is suggested destruction of the cement sheath caused by operation pressure should be taken into consideration in the design of acidizing and fracturing operation.