Drill-string failures continue to be a costly problem for the oil industry. To reduce the occurrence of these failures, operators and drilling contractors typically employ service companies to perform periodic nondestructive inspections to remove damaged tubulars from service. Nonetheless, drill-string failures continue to occur, most often as a result of some form of metal fatigue. This paper presents the results of several field evaluation programs which were conducted to assess the performance of commercial drill-string inspection services employing conventional nondestructive testing techniques. A practical estimate of the effectiveness of these commercial inspection services is made using modern fracture mechanics concepts and fatigue crack growth data obtained from full-scale testing. Based on the data presented in this paper, commercial drill-string inspection services are found to be statistically quantifiable, however their effectiveness is substantially less than optimum. Improved flaw detection technology is needed to most effectively reduce typical downhole fatigue failures.

You can access this article if you purchase or spend a download.