Decommissioning Insight 2017

Approaches to Cost Reduction in Well P&A As the largest category of decommissioning expenditure, well P&A is an important area 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 measures being explored to reduce costs: • A campaign approach – carrying out multiple well P&As in a campaign allows mobilisation costs to be spread across several wells and incremental improvements in technique 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-platform campaigns spanning several years. • 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. • Continued investment in technology – technological advancements continue to drive down costs in well P&A. The newly formed Oil & Gas Technology Centre (OGTC) put out a call offering match-funding for concepts and ideas that could drive transformation in well P&A. Four new technologies are currently being explored, focused on three key themes: new barriers – placement and materials; verification of permanent barriers; and optimising P&A scope. • Optimising the activity schedule – for platform wells this could mean carrying out P&A in an order that reduces the distance the drilling derrick must travel across the platform between wells and leaves the highest performing wells until last. • Cross-operator collaboration – by vessel sharing and adding wells to the campaigns of other operators in the area, there are opportunities for cross-operator campaigns.

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• Alternatives to the existing drilling derrick – considering rig-less methods, or removal of the topsides so that a workover rig can be used.

• Early removal of subsea infrastructure – reducing the amount of subsea infrastructure around the well-site prior to carrying out subsea well P&A reduces the time spent manoeuvring around complex subsea infrastructure landscapes.

• Assessing the well condition – using a light well intervention vessel to set plugs and carry out logging on the subsea well stock to assess their condition prior to beginning the campaign.

The approach ultimately adopted to carry out well P&A 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 learnt through conferences and forums. This area continues to be one of significant development and progress.

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