Session: 02-12-01 Reliability Based Maintenance and Inspection Planning

Submission Number: 153397

A Cost-Effective Computational Approach to Integrate Offshore Inspections
Planning and Routing Vessels 

The oil and gas industries operate critical equipment, particularly in offshore platforms. Failures in subsea equipment can lead to significant environmental damage and endanger human lives. Therefore, ensuring reliability and compliance with regulatory standards is always under investigation. One important measure is the periodic inspection of equipment, enabling predictive maintenance and avoiding disasters.

However, the high cost of these inspections makes it essential to properly define priorities and optimize planning. Traditionally, these plans are developed by experts with extensive experience, who create inspection schedules for specific equipment and plants. As an alternative, computational tools have been proposed to assist these experts in the planning of these operations.

This study aims to investigate an approach to reduce the computational cost of a tool designed for planning inspections of offshore equipment and the routing of vessels involved in these operations. The tool employs the Non-dominated Sorting Genetic Algorithm II (NSGA-II) to optimize system-wide risk and the total cost of operations while using an Ant Colony Optimization (ACO) algorithm for vessel routing. The risk is calculated based on a Top Logic Model (TLM). The total cost includes the inspection method[MM1] , the fixed cost (rental) of vessels allocated for these inspections, and the route required to reach the plants.

The approach analysed in this study integrates the vessel routing task in the optimization process. Initially, the optimization proceeds focusing solely on the inspection planning. Once the genetic algorithm has converged on the most promising regions of the solution space, the ACO algorithm is then applied to incorporate routing. This approach is compared in terms of risk, inspection plan costs, and computational efficiency to two baseline methods: one where routing is integrated from the first generation of NSGA-II, and another where routing is performed as a post-processing step.

Presenting Author: Adriana Miralles Schleder Naval Architecture and Ocean Engineering Department, University of São Paulo (USP)

Presenting Author Biography: Postdoctoral at the Laboratory of Analysis, Assessment and Risk Management in University of São Paulo and currently works on topics related to Risk Analysis and Safety in Offshore Oil and Gas Operations.