Subsea Asset Life Extension in Harsh Environments | OneSubsea
Tech Paper
Location
North Sea, Europe, Offshore
Byline
Benjamin Robert Coupland, Mike Avery, Robert Greenaway, and Phillip Adam Rice, OneSubsea; Douglas Weir, BP North Sea
Society
OTC
Paper Number
30564
Presentation Date
May 4–7, 2020
Products Used
Premium

Subsea Asset Life Extension in Harsh Environments

Abstract

West of Shetland, BP North Sea discovered they had a problem with subsea tree mounted pressure and temperature sensors that whilst dual redundant, still completely failed over time. The measurements are required by the local regulatory body to comply with monitoring of asset integrity and as such once failed the subsea trees were forced to be shut in. Reinstating this production-critical monitoring equipment significantly reduces downtime and deferred production. Later in the life of the field the same damage mechanism that contributed to erosion and fouling of tree mounted sensors had also begun to reduce injectivity within the subsea injection wells and eroded the subsea insert retrievable chokes installed on those trees. BP North Sea initially planned for a campaign of choke insert replacements but later realized the ideal opportunity to incorporate stimulation treatments during the same intervention campaign.

The original retrofit package restored an injection well at a cost saving of 70% compared to conventional solutions. However, continued development led to a next generation retrofit package which allowed streamlined configurability to suit a range of choke types across the BP's subsea infrastructure. This enabled life extension whilst introducing enhanced functionality, all whilst optimizing inventory and minimizing capital investment. In parallel, well stimulation operations on 4 water injection wells yielded injectivity improvements of up to 300%, compelling BP to continue to plan further stimulations for future wells. This scenario led to the next generation of retrofit packages including an additional feature of a dedicated hydraulic access point. The access allowing more efficient stimulation operations and providing significant cost saving in terms of vessel time and in-field operations.

The paper discusses the benefits of combining production enhancement technologies and well status monitoring sensors to enable significant improvements in field recovery. Production improvement metrics and lessons learned shall be shared to provide a robust economic justification.

Operational lessons learned from these various activities show how modularity and product streamlining can significantly reduce operating expenditure, time in field, and overall safety of a product.

Collaboration with invested parties can offer additional sources for product improvement which further contributes to product optimization and successful project execution.

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