DETECCIÓN DE DAÑO EN SOLDADURA DE RISERS RÍGIDOS EN AGUAS PROFUNDAS, UNA METODOLOGÍA PROPUESTA

Abstract

Historically, economic growth in industrialized countries is depends directly on natural resources, such as oil, depletion of oil in shallow water is expected. For this reason, the international oil industry has moved to inaccessible locations because of the depths in which deposits are for oil exploration and exploitation. The Mexican oil industry is not the exception. It is not easy to carry out the oil exploration and exploitation process in deep waters, pushing the limits of engineering and technology as they face greater challenges and difficulties than those in shallow water. One of the problems is fatigue in welded joints of risers, of those joints located in areas with higher susceptibility to fatigue. The failure of a production riser could cause severe environmental damages with high economic losses. This study provides a new methodology for detecting fatigue damage (loss of stiffness) in welds of steel rigid risers in deep water. The methodology uses the Index Damage Method, IDM (Stubbs et al., 1993) and the Difference Modal Slopes Method. These methods analyze the changes of the slopes of the system in a state of the riser without damage with respect to a damaged riser. The relationship between the two states is used to locate damage, which not depend if a single or multiple damages (two damages simultaneous). In addition it was corroborated that damage results using the first derivates of the modal shapes are more precise than the ones from just modal shapes.