PROBABILISTIC RISK ASSESSMENT OF OFFSHORE BLOWOUTS

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2021-6-15

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ELSALİH, MUHAMMED

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A blowout is the eruption of underground reservoir fluids to the surface during drilling operations. This has devastating results, which are described by the serious impact on human health, environmental problems, and economic loss. Blowout events are unpredictable due to uncertainty of how they evolve. Blowout risk usually lies with parts of the safety system that are expected to function fully, and prevent blowouts. Fault Tree Analysis (FTA) is a graphical method offering a way to identify Causal Factors (CF) of the safety system failure, and to evaluate the contribution level of each event to blowout. In this study, an FTA model for offshore blowout probability is mapped to a Bayesian Network (BN). This BN-based model is utilized for Probabilistic Risk Assessment (PRA) of hazards, accounting for uncertainty in both safety system failure rates and subsurface formation pressures. To the best of our knowledge, this is the first time all of the commonly encountered safety barriers are combined in a single PRA analysis. The PRA is performed using importance measures of FTA roots. According to results herein, the blowout event is attributed mostly to human error in monitoring safety barriers. Also, blowout events are highly probable due to inability to precisely identify abnormal subsurface pressure zones. Finally, casing failure is found to be the third significant contributor to blowout.

Subject Keywords

Probabilistic Risk Assessment, Bayesian Network, Fault Tree Analysis, Blowout, Drilling

URI

https://hdl.handle.net/11511/91334

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Northern Cyprus Campus, Thesis

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Citation Formats

M. ELSALİH, “PROBABILISTIC RISK ASSESSMENT OF OFFSHORE BLOWOUTS,” M.S. - Master of Science, Middle East Technical University, 2021.