Experimental Analysis on Galling Cause of J55 Long Round Thread Casing

The galling accident of 139.7 mm ×7.72 mm J55 long round thread casing occurred during casing running down in one well. In order to find out the galling cause, the test procedure based on the casing well running down process in oil field was instituted, and the makeup and breakout tests with the full size casing samples were carried out. The effect of makeup parameter on galling was found out. It was deduced that the cause of casing galling accident in oil field was not only related to abnormal operation, but also related to casing quality according to the test results. The abnormal operation in oil field was pointed out by comparing makeup process in oil field with that in lab. The antigalling performance of casing was researched, and the problem of thread machining quality was found by analyzing galling morphology of the casing.