Evaluation of the dynamic loads impact on the conditions of drill string failure during tripping operations

The conditions of drill string failure during tripping operations with external or internal transverse annular cracks were defined. At the same time, considering the experimental evaluation of the force criterion for failure of metal of backup and operated drill string pipes, the interrelationship between the depth of the critical external or internal transverse annular cracks in drill string pipes with the weight of the drill string was established, considering the effect of dynamic loads during tripping operations. It was determined that dynamic loads during run-in-hole operations are more dangerous at depths of more than 3.7 km, while at lower depths, the dynamic loads occurring during pulling out of string are considered more dangerous. It was demonstrated that, when pulling out operated drill strings, internal transverse annular cracks at depths exceeding 1.1 km, are more dangerous than external ones, while at depths up to 1.1 km the external transverse cracks are more dangerous.