Reliability of Gulf of Mexico Deepwater Slopes Available to Purchase

This paper describes the methodology used by BP on two deepwater projects to assess the reliability level of submarine slopes in the deepwater Gulf of Mexico environment. The paper describes the necessary steps in the analyses: establishing a geological model, properly characterizing the slope geophysically and geotechnically, carrying out deterministic slope stability analyses, performing a thorough review of potential triggering mechanisms, assessing how the slope safety factor will evolve over time, and estimating the annual probability of failure of a given slope. Possible means of estimating annual probabilities of failures from a FORM analysis are presented. The paper establishes that, even if a FORM analysis gives a relatively high probability of failure, the annual probability of failure can be several orders of magnitude lower if the trigger mechanisms are non-random and slow acting.