Evaluating Aging Offshore Platforms for Next CCS: Path to Sustainable Decommissioning

Abstract Carbon capture and underground storage (CCUS) is considered crucial in the quest to achieve net zero carbon emissions by 2050. With over half of Malaysia's offshore assets being more than 30years old and nearly 150 platforms scheduled for decommissioning by 2031, theses aging infrastructures are identified to be the best enabler to improve on the economic assessment and enhanced the possibility for offshore CCS development projects. A series of structural integrity evaluations, including Structural In-Place & Foundation Study, Spectral Fatigue, and advance global ultimate strength analysis, were conducted to assess an aging offshore complex for the largest CCUS project in Southeast Asia. These evaluations were combined with a Sacrificial Anode Requalification Study to check corrosion status as the platform nears the end of its design life. This paper uses the Structural Integrity Management (SIM) framework to evaluate the current structural integrity of chosen platforms, highlighting their potential and limitations for CCUS purposes based on in-service assessments. Although the offshore facilities are 28 years old with over 5 meters of seabed subsidence at the designated location, engineering studies have successfully deemed the asset as fit-for-service for the next 30 years based on the new CCS project design life. This wholesome qualification assessment successfully justifies some offshore campaign scope removal, thereby significantly reduced the CAPEX for offshore CCS development cost. The studies indicate a substantial reserve strength and sufficient remaining fatigue life, providing important insights into the key technical factors that uphold the structural integrity of identified platform. This discovery offers the oil and gas industry an enhanced opportunity to develop a sustainable approach for decommissioning platforms nearing the end of their service life by adopting repurposing strategies, thereby promoting the progress of the offshore renewable energy sector.