Estudo da influência da fadiga por fretting na vida em fadiga de tubos de perfuração de poços de petróleo

Abstract

Numerical models were developed aiming to assess the influence of Fretting Fatigue phenomenon over the prediction of fatigue life of petroleum wells drilling pipes. The objects of study are aluminum drill pipes linked by steel tool joints, which constitute the drilling string. Early failures observed on tool joints were studied under the lens of Fretting Fatigue. Parametric variations were performed in order to build a Fretting map, a graphical representation, which enables to visualize the occurrence of Fretting phenomenon in function of select variables and categorize zones considering the risk of manifestation of the phenomenon. The Fretting map was created by the extraction of different parameters from numerical models varying bending loads, tension loads and internal pressure loads. It was presented the correlation between experimental tests executed with fullscale samples and Fretting maps using different variables. At the end, the obtained results were compared and discussed, so that it was possible to determine freeFretting zones and the parameters that are more relevant for the Fretting map construction.