Reliability and Maintenance Optimisation for Offshore Oil and Gas Production Facilities in the Nigerian Continental Shelf

This dissertation develops and validates a comprehensive reliability and maintenance optimisation framework for offshore oil and gas production facilities operating on the Nigerian continental shelf, addressing the scarcity of location-specific reliability research and the misapplication of North Sea and Gulf of Mexico-derived reliability data to West African offshore operational contexts. Nigerian continental shelf offshore facilities contend with a distinctive operating environment characterised by warm water temperatures affecting material degradation, high marine biological fouling rates, subsea infrastructure shared across multiple producing fields, and logistics challenges arising from limited offshore service vessel availability, all of which systematically alter component failure rate distributions and maintenance task accessibility compared to better-studied offshore environments. The research constructs an original Nigerian continental shelf reliability database from failure records of six hundred and twelve equipment items across four platforms, applies competing risk models to analyse failure time data with multiple failure modes, and develops a maintenance optimisation model using a genetic algorithm to minimise total expected cost per unit of oil production over a twenty-year field life. Monte Carlo simulation quantifies the impact of weather-related maintenance access constraints on optimal maintenance interval recommendations. Original contributions include the Nigerian Offshore Equipment Reliability Handbook, a maintenance access probability model for West African offshore logistics conditions, and a dynamic maintenance interval adjustment algorithm. Keywords: reliability optimisation, offshore oil and gas, maintenance modelling, Nigerian continental shelf, Monte Carlo simulation