(54cx) Optimization of Blowout Preventer Design for Optimal Cost and Reliability

Optimization
of Blowout Preventer Design for Optimal Cost and Reliability

Denis Su-Feher, Nilesh Ade, Bin Zhang, Yogesh Koirala, and M. Sam Mannan

Mary Kay O'Connor Process Safety Center, Artie McFerrin Department of
Chemical Engineering, Texas A&M University, College Station, TX,
77843-3122, USA

Abstract

Incidents such as the Deepwater Horizon blowout highlight the
necessity of reliable, well designed blowout preventers (BOP) on offshore
drilling platforms. Even if a blowout does not occur, extensive economic loss can
occur when a BOP fails due to the expenses of performing corrective
maintenance. Therefore, a well-designed, well maintained BOP is crucial to
safer operation of a drilling platform. On the other hand, it is not
practicable to overdesign the BOP as this will result in increased cost with
little change in reliability. An optimized BOP design is necessary to balance
the capital and operating cost of a blowout preventer with its risk of failure.

The capital cost and operating
cost must be considered when designing a BOP, along with its reliability over
time. A previous study has shown that a model based on fault tree analysis can
relate the failure probability of each component in a BOP design to its overall
failure probability and provide a globally optimized preventive maintenance
schedule with minimum maintenance cost subject to a minimum reliability
threshold. A number of maintenance schedules can be generated from this model,
as well as a Pareto-optimality frontier that demonstrates the optimal maintenance
cost vs reliability of a particular design.

This study presents a number of
BOP designs and generates a corresponding Pareto-optimality frontier for each
design. The reliability of each design is compared, which can be used to optimize
the design of a BOP by considering the capital and maintenance cost for a
number of different designs. A Pareto-optimality frontier is derived for all
defined BOP designs, which simultaneously determines the optimal design and
preventative maintenance schedule for the BOP.

Keywords: Safe
Design, Asset Integrity and Reliability, Upstream, Blowout Preventer, Preventative
Maintenance, Multi-Objective Optimization, Simultaneous Design and Scheduling