Decommissioning Insight 2018

DECOMMISSIONING INSIGHT 2018

Approaches to Cost Reduction in Well Decommissioning As the largest category of decommissioning expenditure, wells are an important area in which to drive cost reductions and efficiency improvements. Oil & Gas UK expects costs to continue to fall as industry experience grows. Operators have reported the following successful measures to reducing costs based on lessons learnt: • A campaign approach — Decommissioning multiple wells in one campaign means mobilisation costs are spread across several wells and incremental improvements in approach can be cascaded across the campaign. Some operators have reported time savings per well of more than one-third over the course of large, multi-year campaigns. • Adoption of a risk-based approach — Analysing the risk to develop a scope of work that is appropriate on a well-by-well basis has significantly reduced costs for some operators. Each well has a different risk profile and the scope of work is developed accordingly. • Cross-operator collaboration — By vessel sharing, adding wells to the campaigns of other operators in the area, and opportunities for cross-operator campaigns. • Continued investment in technological advancements — Technological advancements continue to enable new ways of working which drive down cost. The Oil & Gas Technology Centre (OGTC) currently has ten well decommissioning projects ongoing in its Wells Solution Centre. These projects are actively seeking to create efficiencies and reduce expenditure in well decommissioning. • Optimising the activity schedule — For platform wells, this could mean ordering work to reduce the distance the drilling derrick must travel across the platform between wells, leaving the highest-performing wells until last. • Alternatives to use of the existing drilling derrick — Consideration of a wide range of alternatives to the existing drilling derrick for well decommissioning such as rigless methods, or removal of the topsides to enable a workover rig to be used. • Early removal of subsea infrastructure — Reducing the amount of subsea infrastructure around the well-site prior to carrying out subsea well decommissioning reduces the time spent manoeuvring around complex subsea infrastructure landscapes. • Assessing the well condition — Using a light well intervention vessel (LWIV) to set plugs and carry out logging on subsea well stock to assess the well condition prior to beginning the campaign. The approach ultimately adopted to carry out well decommissioning depends on various factors, with no single approach being appropriate for every situation. Operators are learning from each other through proactive networking and sharing lessons through conferences and forums.

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