Failure analysis of drill pipe: A review

• Critical stress concentration points of a drill pipe were discussed.
• It is highly probable that a drill pipe fails at these critical places.
• Different types and reasons of drill pipe failure have been studied.
• Drill pipe failure follows a predictable pattern. The pattern is nothing but fatigue.

Although the drill pipe is a simple tool in the drilling industry, it is the most used and important one. The drillstring failure has two general forms: wash-out and twist-off. These failures begin with mechanical, thermal and corrosion fatigue cracks. On the basis of previously conducted researches, the failure of drillstring is not unknown. However, the occurrence of drillstring failure still is too much. The main reason for this can be due to complex loading, combined stresses and different types of vibrations and moreover, the corrosive and erosive behavior of drilling mud that makes the total condition of the well so difficult to analyze. In this paper, the attention is focused on the analysis of drill pipe failure and the fatigue crack is represented for the root cause of drill pipe failure. The aims of most of published papers are to examine how and why a specific drill pipe is failed and just the main reason of failure for that drill pipe is discussed in detail. In this paper all metallurgical and mechanical aspects of failure that can occur for a drill pipe, are considered and discussed. And finally, this comprehensive review leads to a conclusion that categorizes the primary sources of drill pipe failure into seven major groups and makes some recommendations to avoid them.