METHODOLOGY TO DEFINE THE PROBABILITY OF DETECTION OF FAILURES IN SUBSEA EQUIPMENT CONSIDERING MULTIPLE INFLUENCING FACTORS

Cost optimization of asset management is a central issue in the offshore oil and gas strategy, and risk based approaches has been more and more employed to assist the segment in the concretization of that goal. In this sense, the use of Risk Based Inspection by the petroleum industry has significantly increased. The inspection procedure aims at mitigating the uncertainty related to the asset degradation state, enabling a better quantification of the actual damage, and, consequently, increases the accuracy of remaining life projections. However, information related to the capacity of the inspections methods to detect the failures and the degradation in equipment is scarce in the literature. The effectiveness of an inspection method is commonly associated with the probability of detection function of the failure modes and the development of PoD curves is highly complex. Thus, in this study, a methodology is proposed to obtain detection probability values for different scenarios associated with inspections carried out in offshore environment. Several factors may influence the detection probabilities, in addition, a factor may have greater influence on one method than on another. Therefore, in this paper, it is proposed a new methodology to define the probabilities of detection, which is an evolution of the method proposed by Cuba et al [1] considering the influence of these factors; the methodology consist of four steps: the definition the probability of detection for standardized scenarios, the definition of the influencing factors impact, the definition of the correlation between the probability of detection for standardized scenarios and the influencing factors and, finally, the update of the probabilities according to the scenario analyzed.