Causes Analysis on Swelling of Drill Pipe NC50 Tool Box Joints of AT-16 Well

Thorough investigation on swelling causes of drill pipe NC50 tool box joint which swelled at AT-16 well was done. And based on the analysis results it was considered that drill pipe tool box joints swelled due to over torque during drilling. It was proved that the anti-twisting property of drill pipe with double shoulder tool joints was better than that of single shoulder tool joints in accordance with finite element calculation results and the actual use effect in Tarim oil field. It was suggested that the dill pipe with double shoulder toll joint should be applied in order to prevent tool box joint from swelling in deep and ultra-deep well drilling.