Leakage Cause of High Pressure Straight Pipe in Oil Well

The high pressure straight pipe in an oil well leaked during acid pickling after pressure test. The causes of leakage on high pressure straight pipe were analyzed by means of chemical composition analysis, wall thickness measurement, hardness test, mechanical property test, metallographic examination, SEM and EDS analysis. The results show that the folding defect on the inner surface of the straight pipe was the main reason for leakage. Multiple pickling operations had made the wall thickness of the high pressure straight pipe to be significantly thinned due to corrosion, and reduced the pressure bearing capacity, which was the secondary cause of leakage. The combination effect of the two causes led to the final leak of the high pressure straight pipe.