Asset Integrity and Risk-Based Failure Analysis of Subsea Distribution Units for Offshore Production Applications

Abstract

Subsea Distribution Units are essential components of offshore subsea production systems, providing the distribution of hydraulic power, electrical energy, communication signals, and chemical injection services between topside facilities and subsea production assets. Their strategic position within the subsea control architecture makes them critical to production continuity, operational safety, and overall field reliability. Failures within SDUs can result in significant production deferment, costly intervention campaigns, and increased operational risks, particularly in Deepwater and ultra-Deepwater environments where access for inspection and repair is limited. This study presents a risk-based asset integrity assessment of Subsea Distribution Units using a Failure Modes and Effects Analysis integrated with Criticality Index (CI) evaluation. The SDU was decomposed into its principal subsystems, including hydraulic couplings, chemical injection interfaces, power and communication transmission systems, subsea accumulators, junction boxes, and structural support components. Potential failure modes were identified, categorized, and ranked according to their likelihood of occurrence and operational consequences. The results indicate that power and communication transmission components constitute the most critical subsystem within the SDU architecture. Hydraulic energy storage and distribution systems were identified as secondary contributors to overall system risk, while structural support systems exhibited comparatively lower criticality levels. The findings demonstrate the importance of reliability-centred maintenance, predictive monitoring, redundancy implementation, and advanced asset-integrity management strategies in minimizing failure occurrence and enhancing production availability. The proposed framework provides a practical methodology for supporting risk-informed decision- making and improving the long-term reliability of offshore subsea production systems.

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