Ecosystem Services and Net Environmental Benefit Analysis for Offshore Decommissioning: Partial versus Complete Removal

Some of the oldest offshore oil and gas production platforms and associated infrastructure in Australian waters are at or nearing the end-of-life and are being proposed for decommissioning. Traditional approaches for offshore... [ view full abstract ]

Some of the oldest offshore oil and gas production platforms and associated infrastructure in Australian waters are at or nearing the end-of-life and are being proposed for decommissioning. Traditional approaches for offshore decommissioning involves complete removal of all infrastructure regardless of potential environmental impact yet an emerging focus is on the assessment of ecosystem services provided by established subsea structures. Within recent and developing guidelines for decommissioning, sustainable development is an obligation incorporated into alternative decision-making. This obligation focuses on balancing the economic, environmental and social factors associated with the selected decommissioning alternatives. A net environmental benefit analysis (NEBA) approach, developed to balance the risks, benefits and tradeoffs associated with competing alternatives that focuses on the environmental, economic and social factors inherent within the potential alternatives, is presented from a decommissioning perspective. The approach provides a non-arbitrary, transparent, and quantitative approach to compare between alternative actions using litigation-tested technical and scientific methodologies. The approach helps stakeholders to manage costs while managing site risks, creating environmental, social and economic value, and providing a demonstrable net benefit to the public (e.g., documenting environmental sustainability and stewardship). This paper presents a framework for incorporating NEBA within the offshore decommissioning process as well as presenting recent supporting evidence for the comparatively high ecosystem services value of many offshore marine structures.