Optimizing Inspection Plans for Multiple Oil and Gas Equipment Under Resource Constraints

Safety is critical for many industries where a failure may impact the environment and human lives, such as in the oil and gas sector. Risk-based inspection has been used for years to identify risk levels in operations and to design inspection and maintenance programs to evaluate the most critical failure modes of the equipment. These programs usually are designed considering two main and clearly conflicting objectives, which are to maintain operations at acceptable risk levels while struggling to keep the costs associated with inspections manageable. Therefore, studies have handled this issue as a multiobjective problem and used heuristics to optimize equipment inspection programs in terms of risk and cost. However, in real-world applications, material and human resources restrictions proved to be crucial factors when creating inspection plans for a set of equipment. This paper presents an early stage methodology for optimizing inspection plans for multiple equipment in light of resources availability over time. The proposed methodology considers the appropriateness of inspection methods for this industry and their frequency of use to achieve acceptable risk levels while optimizing resources, reducing costs. The methodology is evaluated using a set of ten Christmas Trees subject to a limited number of offshore support rigs for inspections. The Pareto fronts for different constraint values showed a patent risk and cost improvement compared to a standard inspection plan using fewer rigs.

Keywords: RBI, Optimization, Offshore, Inspections, Multi-equipment, Multiobjective, NSGA-II.

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