Development of a strategic framework for the comparative assessment of pipeline decommissioning options: optimising environment and fishing interests

Lead Research Organisation: Scottish Association For Marine Science
Department Name: Scottish Association For Marine Science


As part of the exploitation of UK Continental Shelf (UKCS) oil and gas (O&G), more than 27,000 km of pipelines have been installed since the 1960s. To date, only 2% have been decommissioned and there has been little research on the consequences of decommissioning to other industries and the environment [1]. Over the next 6-8 years, approximately 5,600 km of pipelines will require decommissioning on the UKCS [2]. Pipeline decommissioning is considered on a case-by-case basis, by the comparative assessment of the available decommissioning options [3]. As part of the comparative assessment, operators must demonstrate to the regulator (the Department for Business, Energy and Industrial Strategy - BEIS) that any proposed strategy meets international obligations to ensure the safety of fishing and protection of the marine environment. In order to do so, a comprehensive evidence-base and a strategic framework for assessing pipeline decommissioning with respect to fishing and environmental interests is required.

The commercial fishing industry is one of largest users of the UK continental shelf (UKCS), and it is known that there is substantial spatial overlap between pipeline infrastructure and fishing [4]. The presence of decommissioned pipelines on the seabed, without rock dump, presents a potential snagging risk to fishers, according to the type of pipeline, seabed type, fishing intensity and gear-type. The UKCS also contains a number of internationally important conservation features (habitats and species), such as those listed in the EU Habitats Directive (e.g. cold-water corals) and those that are included within designated marine protected areas. These conservation features/species (CF/S) are potentially sensitive to pipeline decommissioning as a result of physical impacts, sediment disturbances and the removal of hard substratum which provides additional habitat for the CF/S and/or protection from trawling damage.

This project will result in the quantification of the risks/benefits of all pipeline decommissioning options to both fishing and the environment and the integration of these risks to find the optimal decommissioning solution for each pipe (from the fisher/environmental perspective). This will be achieved by:
1. Combining and collating knowledge of species-pipeline associations gained from analysis of video footage of pipelines (collected routinely by the industry for integrity monitoring), spatial data on fishing patterns and snagging incidents, and data on the distribution and sensitivities of CF/S.
2. Developing spatial 'risk-layers' that can be flexibly combined to evaluate and minimise the relative risks to conservation interests and fishers, across all UKCS pipelines, from all feasible decommissioning options.
3. Embedding the resulting assessment into decommissioning protocols.

Impacts and beneficiaries
The main beneficiaries of the project will be the UK Government, their advisors [5], fishers and the oil and gas industry who will benefit from an enhanced evidence-base that is shared across all sectors. The outputs of the project will facilitate cost-effective, rapid, consistent and transparent decision-making in relation to pipeline decommissioning.

[1] Oil and Gas UK (2013), Decommissioning of pipelines in the North Sea region
[2] Oil and Gas UK (2014), Decommissioning Insight 2014
[3] Department for Energy and Climate Change (2011), Decommissioning of Offshore Oil and Gas Installations and Pipelines under the Petroleum Act
[4] PipeFish - Optimising the decommissioning of oil and gas pipelines with respect to commercial fishing at the scale of the UK continental shelf. NE/N019369/1
[5] Marine Scotland and statutory nature conservation bodies such as Scottish Natural Heritage and Natural England

Planned Impact

The main beneficiaries of the project will be the UK Government, their advisors, fishers and the oil and gas industry. These stakeholders will benefit from an enhanced, publicly available evidence-base that is shared across all sectors. The outputs of the project will facilitate cost-effective, rapid, consistent and transparent decision-making in relation to pipeline decommissioning.

Department of Business, Energy & Industrial Strategy (BEIS)
BEIS are responsible for insuring that any decommissioning programme returns the seabed to a state where it is safe to be fished. Pipeline removal is the preferred option to ensure fsiher-saftey but this is not always technically possible (e.g. where pipeline are very large). BEIS requires a better understanding of the interactions between pipelines, decommissioning options, the fishing industry and the environment which this study will provide. BEIS is also charged with assessing post-decommissioning monitoring protocols; the CA-PipeFish project will highlight which pipeline/pipeline-section is deserving of the greatest post-decommissioning monitoring, for example where the fishing pressure is the greatest.

Marine Scotland Science (MSS)
MSS provides advice to BEIS through the assessment of offshore oil and gas environmental statements. In order to provide the best advice possible, MSS need to better understand the interactions between fishing, pipelines and conservation features. This project will collate data from several sources into a single-access point which will facilitate a rapid assessment of the likely consequences to fishers and conservation features of numerous decommissioning options. This will enable MSS to provide timely, accurate and auditable advice to BEIS from their shared geodatabase.

Oil & Gas UK (O&G UK) and Scottish Fishermen's Federation (SFF)
The O&G UK trade association promotes open dialogue between their membership and other UK continental shelf stakeholders such as fishers. O&G UK also promote safety and environmental awareness and aims to develop industry-wide initiatives to engage with regulatory bodies. The SFF was formed to preserve and promote the collective interests of Scotland's fishermen's associations (representing >80% of the UK's demersal fleet). The oil and gas and fishing industries operate side-by-side in on the UK continental shelf. O&G UK and SFF work closely together to minimise negative interactions between their respective memberships, mainly the snagging of underwater oil and gas infrastructure by fishing gear. In order to further this cause, promote safety and reduce costly interactions both O&G UK and SFF both need to better understand the extent (intensity) and nature (e.g. gear-type, proximity) of fishing/pipeline interactions. This project will, for the first time, develop and bring together datasets that will allow these interactions to be properly quantified. O&G UK and SFF, and through them their membership, will benefit from the common-access-evidence base that will be generated by this project to promote safe decommissioning resulting in reduced expenditure and enhanced safety.

Scottish Natural Heritage (SHN) and Natural England (NE)
SNH and NE, statutory nature conservation bodies, provide advice, based on the best scientific evidence, to central government (e.g BEIS) on how best to safeguard natural wealth for the benefit of current and future generations. In order to provide this advice, conservation agencies require an evidence-base in order to make recommendations for the optimal management option. CA-PipeFish will provide that evidence-base, allow the testing of alternative decommissioning-scenarios and identify where important knowledge-gaps exist.

Further details are provided in the Case for Support.


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Rouse S (2018) Offshore pipeline decommissioning: Scale and context in Marine Pollution Bulletin