Inspection Optimization for Subsea Systems: A Risk and Cost Analysis of a Production Manifold

To ensure continuity and safety in complex offshore operations, managing subsea equipment integrity is fundamental. Optimizing inspection plans is the key strategy for balancing risk control, costs, and integrity. The application of risk-based methodologies and reliability data allows for prioritizing resources on high-impact equipment, such as production manifolds, while avoiding both the over-inspection of low-priority items and the under-inspection of critical components. This paper presents the application of a methodology aimed at defining optimized inspection plans with a simultaneous focus on risk and cost. The methodology's development employed techniques, such as Preliminary Hazard Analysis (PHA), Event Tree Analysis (ETA), Fault Tree Analysis (FTA), and the Top Logical Model (TLM), as presented by Frutuoso and Melo et al. (2025). The information obtained in these stages formed the basis for the optimization phase, which was conducted using in-house software that combines Genetic Algorithms (GA) with the Risk-Based Inspection (RBI) approach. The application of the methodology generated optimized maintenance plans for a representative production manifold, simultaneously considering risk and cost criteria. For comparison, two reference inspection plans were analyzed: (i) a prescriptive plan derived from the recommendations for critical components from the NORSOK D-10 standard and (ii) a conservative plan, both used to establish risk thresholds. Furthermore, the results were benchmarked against a "typical plan" for this category of equipment, identifying alternatives capable of simultaneously reducing both risk and cost. The findings show that the proposed methodology outperforms the plan traditionally used, yielding significant efficiency gains without compromising established safety limits. Therefore, the study demonstrates the approach's potential as a decision-support tool for managing the integrity of subsea production systems, supporting the definition of more effective, economical, and sustainable maintenance strategies for the oil and gas sector.

Keywords: Inspection Plan Optimization, Subsea Production Manifold, Risk Analysis, Integrity Management, Pareto Frontier.