Decommissioning Insight 2019

A global reputation — While various companies in the UK are already present in decommissioning industries around the world, help from international trade organisations such as Scottish Development International (SDI) and the Department for International Trade (DIT) will help ensure success.

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CASE STUDY — CHEVRON

Chevron and its partners are planning for the decommissioning a number of platforms in the Gulf of Thailand. As with all platform decommissioning projects, a range of options are being considered, from complete removal to shore, to leaving all or part of the infrastructure in the marine environment. Aspartof theassessmentof thedifferentdecommissioning options, the role of the structures in the ecosystem is evaluated. To compare the different decommissioning options, Chevron is utilising the NEBA (Net Environmental Benefit Analysis) method. NEBA was chosen to provide an objective and transparent method of comparing the ecosystem service ‘value' of each option.

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3-D Model developed using photogrammetry to characterise marine growth on a platform member

NEBA is typically adopted to help stakeholders understand the environmental and socio-economic benefit associated with different alternatives by using clear and meaningful parameters. In practice, NEBA requires a baseline biological survey of the jackets and adjacent control sites to characterise the ecosystem at each location. The key objectives are to quantify the biodiversity, assess biomass and productivity of the fish and assess the marine growth for each decommissioning option. To support this approach, the level of data required from the surveys is much greater than when undertaking typical techniques such as diver or routine ROV inspection surveys. Therefore, Chevron and its partners have been developing and trialling a number of new technologies, aimed at producing the level of survey detail to support the assessments within NEBA. These technologies include: • Stereo-video remotely operated vehicle (ROV) methods to quantify fish diversity, abundance and biomass • Environmental DNA (eDNA) to quantify biodiversity • 3D Photogrammetry to estimate biofouling area, volume and weight The use of these new techniques is providing Chevron and its partners with detailed and accurate data on ecosystem structure and function to enable quantitative assessments of decommissioning options to be carried out within the NEBA framework.

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