Decision framework for platform decommissioning in California

This article describes the overall decision framework for eventual decisions about decommissioning the 27 operating oil and gas platforms offshore southern California. These platforms will eventually reach the end of their useful lifetimes (estimated between 2015 and 2030, although specific dates have not been determined). Current law and regulations allow for alternative uses in lieu of the complete removal required in existing leases. To prepare for eventual decommissioning, the California Natural Resources Agency initiated an in-depth process to identify and investigate issues surrounding possible decommissioning alternatives. The detailed evaluation of alternatives focused on 2-complete removal and artificial reefing that included partial removal to 85 feet below the waterline. These were selected after a comparison of the technical and economic feasibility of several potential alternatives, availability of a legal framework for implementation, degree of interest from proponents, and relative acceptance by state and federal decision makers. Despite California's history of offshore oil and gas production, only 7 decommissioning projects have been completed and these were all relatively small and close to shore. In contrast, nearly 30% of the California platforms are in water depths (as much as 1200 feet) that exceed any decommissioning project anywhere in the world. Most earlier projects considered an artificial reefing alternative but none were implemented and all platforms were completely removed. Future decisions about decommissioning must grapple with a more complex decision context involving greater technological and logistical challenges and cost, a wider range of viable options, tradeoffs among environmental impacts and benefits, and an intricate maze of laws, regulations, and authorities. The specific engineering differences between complete and partial removal provide an explicit basis for a thorough evaluation of their respective impacts.