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4 challenging asset life extension projects

27-nov-2014

With over half the platforms in the North Sea being at least two decades old – and over 3,000 well conductors in the Arabian Gulf the same age – operators are increasingly faced with the challenge of managing and extending the lives of mature assets.

Read on to see how 4 challenging asset life extension projects by Claxton have delivered safe, reliable and economic solutions to operators’ dealing with aged offshore assets.

REPLACEMENT CONDUCTOR GUIDE EXTENDS PLATFORM LIFE

A recent fabrication contract for a replacement jacket guide assembly project called for a radical Claxton engineered solution.

The splash zones on the offshore platform was subjected to seawater exposure at high levels meaning the existing structure needed replacing completely.

Claxton proposed building the new assembly on top of the old guide using existing structural members for support before removing the old structure underneath. This multi-stage and complicated process required high-precision installation of uprights and beams.

The new guide provided 12 new conductor guides enabling the operator to extend the working life of the platform by another 20 years.

WELLHEAD CONDUCTOR INTEGRITY ASSURED

Claxton’s experience of wellhead systems proved invaluable in helping one of the North Sea’s leading operators manage the integrity of a selection of older platform wells whose construction left a lot to be desired by today’s standards.

During the original installation, some conductors were cut too short meaning there were gaps between the base of the wellheads and the tops of the conductors.

The inspection found the annulus between the conductor and the surface casing revealed significant corrosion.

After examining the wells, Claxton created a bespoke circular clamp for every conductor that bolted around the top with shim plates taking up the remaining gap. This led to Claxton winning a five-year contract with the client to provide future clamp designs.

ADDITIONAL CONDUCTOR GUIDE TO EXTEND PLATFORM LIFE

Claxton were sub-contracted to design, fabricate and install a new additional conductor guide and centralizer in the platform’s splash zone located in the Irish Sea.

However as the project developed, concerns emerged that whipping of the drillstring at the congested cellar deck level may have led to clashes with surrounding steelwork or piping.

To combat this, a temporary guide was used at the cellar deck. The guide was lifted over the side of the platform, slung into place within the jacket structure and firmly secured within a few hours by a crew of abseilers.

The additional conductor guide was a huge success and resulted in the platform’s life being significantly extended.

SLOT RECOVERY ON THE BERYL B PLATFORM

The operator of the Beryl B platform in the North Sea wanted to recover a slot but a 20” tieback riser needed retrieving first.

Concerns over the structural integrity were also raised by the client of the riser’s RS-type connectors as a similar connector had failed during a previous slot recovery operation.

Claxton developed a recovery method that provided an efficient means of recovery and enhanced the riser’s integrity during retrieval. This included supplying a new casing string, complete with smart anchor packer inside the 20” tieback riser, as well as a hot tapping and drilling & pinning machine to complete the operation.

The slot was recovered successfully as requested by the client and Claxton has subsequently used similar equipment packages on other recovery projects.

Asset life extension buyers guide
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Asset Life Extension Buyers Guide

Download our structural asset life extension buyers guide for details on slot recovery techniques, centralizers and replacement platform guides.

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