Artificial reef creation using decommissioned mattresses – environmental performance and fisheries enhancement potential in the North Sea

The North Sea has been the centre of the UK’s oil and gas (O&G) industry since the 1970s. Production for many assets is now declining and O&G-related structures are beginning to require decommissioning. The estimated cost of decommissioning in the North Sea varies widely (e.g. total £30 - £100 billion, with £17.6 billion spend projected for the next 9 years).

Concrete mattresses consist of a 2-dimensional layer of concrete blocks (joined on four sides) that are laid across subsea structures to afford them protection. There are 35,000 – 40,000 concrete mattresses in the North Sea and all will require decommissioning.
Industry is obliged to make a ‘comparative assessment’ to evaluate decommissioning options (e.g removal, leave in-situ) in relation to mattresses. Re-use of materials in coastal defence or around new technologies (offshore wind) is an intuitively better solution to mattress-disposal than alternatives such as onshore landfill. However, before offshore re-use can be considered, the environmental costs-and-benefits must be established.

This PhD aims to support industry and decision-makers by providing them with the necessary evidence to identify the optimal decommissioning option. Re-use of materials has considerable potential to reduce costs to the O&G sector (and taxpayer), and bring cost-benefits to other industries such as offshore wind. This will increase the sustainability of both sectors and generate wealth and competitiveness through cost-reduction.

PhD Details
The environmental implications of different decommissioning options, including re-use as scour protection material (de facto artificial reefs) or in the construction of de jure artificial reefs, are largely unknown. This PhD student will:
1. Review the in-situ reef-effects of concrete mattresses
2. Evaluate potential reef-creation scenarios such as re-use around wind-turbines or direct reef-creation and the potential for artificial reefs in promoting fisheries in temperate waters
3. Evaluate plausible options for siting reefs (both de facto and de jure), determine likely epifaunal colonisation (Note 1) and structure utilisation, particularly by commercial species.
4. Using 3-D photogrammetry determine scale-dependent habitat provision by a range of mattress construction options (this may focus on the Loch Linnhe Artificial Reef as an analogue)
5. Use computational fluid-dynamic (CFD) and/or ecosystem models to evaluate the habitable volume and/or likely ecosystem consequences of various artificial reef creation options.
6. Make recommendations to policy makers on optimising the design of de jure and de facto artificial reefs made using decommissioned concrete mattresses.

This PhD will build on an extensive, existing partnership between the Supervisors and the O&G industry and regulators. These contacts have been developed through the NERC Grants NE/N019369/1 (Note 2) and NE/PO16537/1 where we are actively collaborating with MSS, BEIS, Scottish Fishermen’s Federation, Oil and Gas UK, Shell, BP and SNH among others. We will also promote the PhD student’s research through our contacts in the MASTS Oil and Gas Forum (Wilding and Rouse as co-convenors).

Supervisory team
The main supervisory team will consist of Tom Wilding and Sally Rouse. Tom and Sally will provide overall oversight and guidance and facilitate liaison with industry and regulators. Sally will oversee mapping and data collation aspects of the PhD. Additional supervisors will include Dr Peter Hayes (MSS) to provide further regulatory-context and Natalia Serpetti (SAMS) to provide guidance in relation to ecosystem modelling using models such as Ecopath. The successful applicant will receive formal training in the use of Ecosystem models. The 3-D Photogrammetry and CFD (Note 3) models will be overseen by Drs Andy Mogg and Andy Dale (SAMS) respectively. This PhD forms one of a pair of related PhDs. Close co-operation between the successful candidates is expected. This PhD will be mostly desk-based but, depending on further funding and/or student aspiration, could involve SCUBA field-work on the Loch Linnhe Artificial Reef.

Notes:

1 - we have agreement from BP and ConocoPhillips to use their ROV footage to assess in situ faunal associations and build on work being undertaken on the NERC CA-PipeFish project.
2 - http://gotw.nerc.ac.uk/list_full.asp?pcode=NE%2FN019369%2F1&cookieConsent=A
3 - CFD modelling is optional and depends on the modelling skills possessed by the successful applicant.

Informal project specific enquiries can be made to: [Email Address Removed]