DECOMMISSIONING
Comparative assessment is often
preferred to the alternatives such as multi-criteria decision assessment due to the relative lack of complexity and the opportunity to use both quantitative and qualitative data. Because it’s scalable, comparative assessment is equally applicable to both small and large-scale projects covering a wide range of technical and environmental parameters, as well as cost.
DECOMMISSIONING THE MURCHISON PLATFORM A recent example of the use of comparative assessment in the off shore sector came with the decommissioning of the Murchison platform, operated by Canadian Natural Resources International (CNRI), which was installed in 1979 and became part of an intricate framework, exporting oil onshore to Sullom Voe through a pipeline. Lying in 156m of water, the platform was supported by an eight-legged steel jacket and had topside modules for drilling, production and accommodation. Murchison was one of the biggest steel jacket platforms in the North Sea, with its topside weighing 24,500 tonnes and consisting of 26 modules. Using standard industry
practice, subsea wells were plugged and abandoned. T e topside modules were dismantled and brought onshore to be reused, recycled or disposed of. T e weight of the jacket at 27,584 tonnes including jacket structure, piles, grout, marine growth and fl ooded members dictated a phased removal of the structure and made it a candidate for derogation under the Convention For T e Protection Of T e
Comparative assessment is a popular tool
Marine Environment Of T e North-East Atlantic (OSPAR) 98/3. To assess the most appropriate course of action, CNRI engaged BMT Cordah to provide environmental support to the decommissioning programme and facilitate the comparative assessment process. T is involved fi ve workshops, attended
by all major stakeholders including engineering, environmental, health & safety, shipping & navigation and fi sheries. BMT Cordah, in its role as an independent third-party with wide ranging experience in both comparative assessment and the off shore decommissioning sector, worked with CNRI to design the scoring and ranking system that was used. T e attendees considered the criteria surrounding each aspect of the options and their expert professional opinion was used to score the alternatives. T e culmination of a qualitative and a quantitative assessment provided the basis of the fi nal decommissioning option. Within this particular project, the comparative assessment concluded that there was a signifi cant increase in operational safety risk, technical complexity and cost associated with the full jacket removal compared to partial jacket removal. A partial removal was
INITIATIVE TO CUT DECOMMISSIONING COSTS A
n industry project is being launched that will develop off shore safety case guidance and technology solutions to reduce OPEX spend during
late life and decommissioning phases. ABB in collaboration with Industry Technology
Facilitator (ITF) is launching the project, which will bring together operators, legislators, industry bodies and consultants to address cost-effi cient management of major accident hazards (MAHs) and safety and environmental critical elements (SECEs). For off shore structures in the UK Continental Shelf
(UKCS), there is a legislative requirement to maintain a safety case throughout the operations, late life and decommissioning phases, until completion of the agreed decommissioning scope of works. The industry project will develop guidance that will support operators in managing their off shore safety case in the planning of decommissioning and enable technology opportunities
to be developed that will reduce OPEX spend in late life and decommissioning. There are three primary aims of the project. The
fi rst is to develop industry guidance on end of life (EoL), major accident hazard management (MAHM) and off shore safety cases to supplement existing regulator guidance and facilitate EoL safety case submissions and operations. The second aim is to defi ne key systems, services and
safety critical elements that can safely be retired during late life and decommissioning. Finally, the third goal is to provide a platform for small and medium enterprises to showcase technology solutions that support the industry’s target to reduce decommissioning costs by 35% to 50%. ABB will provide structure, funding, project management, technical safety guidance and facilitate the capturing of knowledge. ●
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