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The NSDG had a full programme of work during 2001 with an emphasis on technology development, joint working and identification of synergies, and re-use of facilities. The North Sea has to date had some experience of decommissioning small gas platforms in the southern North Sea but has very limited experience of large structure decommissioning - on the UKCS this is limited to Brent Spar (Shell) in 1995 and Maureen (Phillips) which began in 2001; although neither of these is a typical fixed steel jacketed structure - Brent Spar was floating and Maureen was designed to be re-floatable.
a) Types of installation
The table below shows the seven types of installation in the UKCS.
Table: Distribution of UKCS installations
| Type of installation |
Number (2002) |
| Steel jacketed platforms (shallow water i.e. <100m) |
197 |
| Concrete gravity structure |
12 |
| Steel gravity structure (previously Maureen) |
0 |
| Floating production system |
6 |
| Steel jacketed platform (deep water) i.e. >100m |
45 |
| Compliant tower |
0 |
| Tension leg platform |
1 |
| FPSO |
16 |
| Total |
277 |
b) Timing of decommissioning
The graph below shows an estimate of decommissioning dates, indicating that the bulk of UKCS decommissioning is likely to occur in the 2010-2030 period. Note this analysis is very provisional in particular a low oil/gas price environment is likely to bring these dates forward, while conversely a high oil price environment will delay decommissioning. (See Graph in Reference Diagrams section)
c) Technology development
This has been progressing in a number of areas:
- Single lift concepts: completion of topside development studies, stimulation of jacket lifting developments, taking ideas to technical maturity.
- Improved backloading: improved understanding of the technical constraints of backloading, identification of potential radical concepts.
- Improved subsea dismantling of jackets: addressing the safety challenges, alternative severing techniques.
- Well abandonment techniques: maximising synergies through best practice of 20 suspended wellhead abandonments (started 2000) (see also Commitment No.5), identifying techniques for improvement.
- Innovative new technology: stimulation and seed funding for new decommissioning technology (with ITF) (see Commitment No.13)
d) Best practice sharing, joint working and identification of synergies
The DTI Guidelines encourage the exploitation of synergy between projects and the realisation of savings. TEDS (The Early Decommissioning Synergy group) is the industry forum for identifying such areas of synergy. A subgroup of TEDS, the Decommissioning Technology Forum, has been set up to assist novel concepts to market, including for example c) 1 to 3 above. There have also been ongoing efforts to promote inter-company cooperation, exchange best practice and reduce duplication. (See also Commitment No.5)
e) Re-use of facilities
NSDG has been working to promote the acceptance of facility re-use as a viable and attractive option, in line with the hierarchy for waste management (reduce, re-use, recycle, dispose). The issue of re-use is complex. A successful match of facilities with requirements is governed by a number of factors, any one of which might render the possibility of re-use impossible. It is more likely that parts of a platform will be re-used as parts of other developments or for other non-oil purposes entirely.
An electronic database has been set up to enable the exchange and match of information. Electronic Marketplace for Information on Decommissioning of Offshore Installations (EMIDOI) supported by the EU - will provide a virtual marketplace to gain up-to-date data & information on planned, on-going and executed decommissioning projects, details on installations, environmental impact assessments, decommissioning technologies, and business directories of decommissioning capabilities and services. Links are also being pursued with the Gulf of Mexico experience.
f) Stakeholder engagement
UKOOA carried out a major exercise supported by an independent facilitator to interview a range of stakeholders interested in the decommissioning and derogation of large steel installations. This was finalised in 2000 and the report can be found on the decommissioning section of the UKOOA website. Since then stakeholder engagement has been at a company level for those structures facing decommissioning - Phillips carried out such an exercise for Maureen platform, and TotalFinaElf and Kerr McGee are doing so for their plans concerning Frigg and Hutton respectively. For example, Phillips made contact with over 600 interested parties taking in any individual or organisation that had views or who wished to be kept informed.
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Sustainability Strategy Commitments
