Automation of Marine Growth Analysis for Decommissioning Offshore Installations

Permanent offshore structures form artificial reefs which provide attachment and settlement sites for marine organisms. In the UK, some of the oldest platforms have been in the water for over 40 years and have considerable colonisation of marine organisms. Marine Growth organisms generally include seaweeds, soft corals and mussels in the areas where light penetrates(photic zone) as well as anemones, hydroids and cold-water corals on the deeper sections of the platforms.

One of the first marine growth studies published was on the Montrose platform back in 1982; and significant discoveries have been made during offshore installation marine growth assessments since then, such as the first discovery of the CITES Listed Lophelia pertusa coral growing on offshore platforms during the decommissioning of the Brent Spar storage buoy, the with results subsequently being published in Nature in 1999. L. pertusa as since been recorded on the majority of northern North Sea platforms - and therefore their presence on the structures may be contributing to the connectivity of the protect reefs in the UK and Norway.

Marine growth causes issues for the oil and gas industry (operators) by adding additional weight to the structure which may cause damage and impair visual inspection of important equipment, both in routine and decommissioning scenarios. New areas of interest have also developed around platform marine growth, including the potential for marine invasive species, potential "stepping stone" habitats, artificial reefs for conservation (e.g. de-facto MPAs) or fish using the structures for food and shelter. In areas of the Gulf of Mexico, a "rigs-to-reef programme", (the conversion of offshore platforms into designated artificial reefs) is underway. However, in Europe, particularly in the North East Atlantic OSPAR region, there is a requirement to remove all offshore infrastructures from the seabed (although derogations may be granted). As part of the decommissioning plan, an operator may be required to assess the extent of marine growth on a platform to determine the additional weight added to the platform (for structure removal) or for potential organic waste disposal and especially if species of conservation importance (e.g. Lophelia and Sabellaria) are present.

This project will use a pre-devolved method (CoralNet) to analysis images of marine growth on offshore structures. The method will allow for more images to be analysed, compared to traditional assessment methodology and will allow for a more consistent approach, potentially providing for a good long-term monitoring tool. In addition, finding new and innovative monitoring methods, is not only about collecting data in the field, but also about how the data should be analysed, with this project will contribute.

This project will aim to address impacts (outlined above) of marine growth by utilising a method for the automated analysis of marine growth on offshore installations using the method developed through the CoralNet project.

The project partners (BP, DECC and Scripps institute of Oceanography, San Diego) and the project advisor/sub-contractor (BMT Cordah Ltd)have been involved throughout the proposal stage, and will continue to be involved in the project through the provision of data and survey footage, and support for method training and assessment. The project addresses issues that are relevant and timely to environmental assessment of offshore decommissioning, both in the UK and globally. The method proposed in this project is critical to help develop our knowledge related to the derogations for leaving in place as stipulated under the OSPAR regulations.

The project offers a number of benefit to the business for not only the operators currently undertaking (and thinking about) decommissioning, but also the regulators and research community. It will contribute to the development of a potential long-term monitoring strategy of decommissioning and decommissioned structures. Furthermore, the method offers an efficient and consistent assessment approach allowing for comparative assessment - something the industry and academia are keen to promote through the availability of environmental data. It is felt throughout the industry that thus us still a lack of scientific understanding about how these offshore structures contribute to the environment once decommissioned (if derogations to leave part of the structure are in place, or how the environment is impacted upon complete removal); and their overall contribution to ecosystem function and services offshore. It is hoped that this type of study will contribute to the determination of the extent of their environmental benefit. It would also be hoped that a study of this nature could expand beyond the initial scoping study to provide evidence to regulators and policy makers such as DECC and OSPAR, with the aim to support regulation change and development and long-term monitoring.