Fatigue Accumulation in Drillstring

One of the major areas where there is potential for cost reduction in drilling industry is mechanical damage on drill string. The purpose is to study most major mechanical damages on drill string such as fatigue failures. To ensure mechanical integrity of drill string, it is necessary to predict the expected loading on each part and then show that these loads do not lead to failure of drill string. Then the effect of fatigue on drill string failures will be discussed. This review of stress analysis of drillstrings emphasizes the central role of torque drag calculations and closed form solution and then presents a methodology for fatigue lifetime predictions devoted to threaded assemblies. This technique is based on a mechanical analysis and a fatigue analysis. The fatigue analysis is performed using the Dang Van criterion which has been extended in the finite lifetime domain. Then some ways have been suggested to eliminate of drillstring failures

کلیدواژه ها:

Stress Analysis ، Mechanical Damage ، Torque drag calculations ، Fatigue ، Closed-form Solutions ، Stress concentration