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Globally, aging offshore oil and gas (O&G) platforms face resource depletion, and regulations often demand platform removal through decommissioning. In the North Sea, >€90 billion will be needed for decommissioning by 2060. However, the influence of O&G platforms on fish communities is poorly understood. This challenges predictions of possible fisheries scenarios associated with different decommissioning options. Here, we examined the role that North Sea platforms played on fish communities. We explored patterns of fish abundance and body size variation along transects from O&G platforms comparing catch per unit effort data. Fish abundance was positively associated with O&G platforms. Atlantic cod, plaice, saithe, and mackerel were most abundant near platforms. Similarly, larger Atlantic cod were near the O&G platforms. Our study provided information for decision‐making regarding platform decommissioning scenarios by evidencing O&G platform habitat provisioning for various commercial fish species. [ABSTRACT FROM AUTHOR]

The decommissioning of offshore platforms has been increasingly discussed due to its economic, social, and environmental impacts. The high complexity of this multilevel context pushes for the adoption of a service ecosystem view to explore the value propositions and actors' relations involved in resource exchanges. This study follows a mixed‐method approach based on semistructured interviews conducted with oil and gas stakeholders and content analysis of the secondary data collected. The results highlight the ecosystem elements and identify the main drivers for sustainable growth in the process of the reconversion of oil and gas assets. A "meta" level is theorized to investigate how the actors' purposes can be harmonized with an ecosystem's goal to encourage the diffusion of a sustainable‐oriented culture in the context of offshore decommissioning. In this sense, the study provides several insights for researchers and professionals in both the local and national governance field and the oil and gas industry. [ABSTRACT FROM AUTHOR]

Taxpayers and operators worldwide have significant current liabilities associated with decommissioning of offshore Oil & Gas (O&G) assets. Consequently, decommissioning is at the forefront of industrial, governmental, and non-governmental agendas. Decommissioning is a highly complex activity with health, safety, environmental, social, economic, and technical implications. Increasing scientific evidence supports that manmade subsea structures create hard, artificial reef habitats that provide ecological and social benefits to society. Given the significant uncertainty regarding how subsea structures should be retired at the end of their operational lifetimes, it is necessary for governments, taxpayers, and operators to understand the risks and benefits associated with potential decommissioning options. Currently, the North Sea decommissioning process is based on the policies and direction of the Oslo and Paris Convention’s (OSPAR) Decision 98/3 and follow comparative assessment (CA) multiple-criteria decision analysis (MCDA) guidelines to determine the best overall strategy for decommissioning subsea structures; however, CA MCDA processes can be biased, ambiguous, difficult to use, interpret, and replicate, and limited in their consideration of multigenerational benefits. Consequently, to assist decision-makers in understanding and evaluating options and associated benefits for decommissioning subsea structures, this study adapted the net environmental benefit analysis (NEBA) framework to supplement and strengthen the CA process for evaluating decommissioning options for offshore O&G facilities. The net environmental benefit analysis based comparative assessment (NEBA-CA) framework is presented that addresses the growing need for a practical, quantitative, scientifically robust, defendable, and transparent MCDA approach to determine optimized decommissioning strategies for subsea assets. Increased transparency in CAs will provide an additional layer of credibility with regulators and society. The approach is data driven and a desktop analysis mainly relying on existing data. Using a North Sea case study, this work demonstrates the ability of NEBA-CA to resolve inherent complexity in comparing decommissioning options, thereby supporting operators in working with regulators to decommission assets in a way that maximizes ecosystem service benefits to society while managing site-related risks and costs. The NEBA-CA framework supplements and strengthens the standard CA process by 1) incorporating quantified metrics including multigenerational ecosystem service benefits and risks, 2) excluding front ranking (scoring) or weighting of metrics, and 3) providing consistent graphical displays to support visual differentiation of options and metrics.

There are currently thousands of offshore platforms in place for oil and gas extraction worldwide, and decommissioning efforts over the next three decades are estimated to cost more than US$200 billion. As platforms reach the end of their useful lifetime, operators and regulatory agencies will assess the environmental impact of potential decommissioning strategies. Among the many factors that will be weighed in preparation for these major economic and engineering challenges is the fate of the fish and invertebrate communities that inhabit the structures underwater. Offshore platforms act as inadvertent artificial reefs, and some are recognized among the most productive fish habitats in the global oceans. We present a model for forecasting changes to fish communities surrounding offshore installations following a series of decommissioning alternatives. Using 24 platforms off southern California, we estimate fish biomass and somatic production under three possible decommissioning scenarios: leave in place, partial removal at 26‐m depth, and complete removal of the platform and underlying shell mound. We used fish density and size data from scuba and submersible surveys of the platforms from 1995–2013 to estimate biomass and annual somatic production. Bottom trawl surveys were used to characterize future fish assemblages at platform sites under the complete‐removal decommissioning scenario. Based on a conservatively modeled extrapolation of the survey data, we found that complete removal of a platform resulted in 95% or more reduction in the average fish biomass and annual somatic production at the site, while partial removal resulted in far smaller losses, averaging 10% or less. In the event that all surveyed platforms are completely removed, we estimated a total loss of more than 28,000 kg of fish biomass in the Southern California Bight. Platform habitats, which attract reef‐dwelling fish species, had minimal overlap in community composition with the surrounding soft‐bottom habitat. To best serve the wide range of stakeholder interests, the site‐specific biomass, productivity and species composition information provided in this study should be incorporated into strategic decommissioning planning. This approach could be used as a model for informing "rigs to reefs" discussions occurring worldwide. [ABSTRACT FROM AUTHOR]

Complexity and costly nature of operations involving in the decommissioning process require huge investments to be done during the lifetime of the field for its decommissioning phase of the total project. This work offers a knowledge-based decommissioning alternative strategy selection system for fixed offshore jacket platforms in the Persian Gulf. In this method, the alternative option of installing offshore wind turbines (OWT) as the most probable economic feasible alternative to decommissioning on an abandoned platform jacket structure in the Persian Gulf is proposed. In this regard, costs and benefits study between two strategies are considered; one total decommissioning and the other installing an OWT on the jacket structure of a local platform in the region. It is found that the second strategy is beneficial and saves near 9 million US dollars for company. Furthermore, the company earns the technology and experiences with OWT installation and operations and would be a technical leader in the region for coming years as well as improve the total rate of greenhouse gas emission production in the region.

Offshore drilling raises the issue of disposal of platforms at the end of their productive cycle and re-use as artificial reefs has been proposed. The wreck of the “Paguro” drilling platform, which sank in the northern Adriatic Sea in 1965, offers the opportunity to study the performance of offshore structures as artificial reefs in a region where this solution has not been explored before. We provide a description of the macrobenthic assemblages present at the wreck at different sites and at different depths, based on destructive and photographic sampling. Results show that the wreck has been colonized by a rich and diversified fauna. Primary space has been dominated by mussels and oysters, which provide suitable habitats for a variety of benthic invertebrates. Assemblages vary among sites, species richness is greatest at those sites facing prevailing currents. Distribution patterns vary vertically, evenness (Hill's N10) decreasing significantly with depth. It is argued that the results contribute to the background knowledge required in rigs-to-reefs programmes. Copyright 2002 International Council for the Exploration of the Sea. Published by Elsevier Science Ltd. All rights reserved. [ABSTRACT FROM PUBLISHER]