Well abandonment and subsea cutting projects often throw up interesting challenges, demanding flexibility and accuracy from both workers and the machinery they are using to get the job done.
Faced with completing the decommissioning project within a tight budget and time scale, it can be hard to deal with the unforeseen and keep a project on track – particularly when operators dealing with decommissioning campaigns are often charting new territory.
Subsea abrasive cutting can be a tricky operation requiring accuracy and expertise. With SABRE?, Claxton has created an abrasive cutting machine designed specifically for simultaneously severing all the casings in a string.
The Claxton SABRE? abrasive cutting system is proven to simultaneously sever all the casings in a well, regardless of casing loading, eccentricity, or annuli contents.
SABRE’s abrasive water jet makes light work of multi-string casings. Shown here: the abrasive jet being tested overboard prior to being run for a subsea cut.
Proven technology
SABRE? has proven to be an invaluable tool and has seen successful use on some of the most significant abandonment campaigns. SABRE’s abrasive jet exits the tool at transonic speeds – making light work of even composite materials such as cemented casings.
Using a jet of naturally occurring cutting components (garnet, water and air), SABRE? has a low environmental impact. The system can be deployed from a vessel or platform, allowing simultaneous abrasive cutting of multiple well casings without impacting adjacent infrastructure.
Benefits of SABRE?
- Casings can be cut and recovered simultaneously or individually
- Can enter wells down to 6.5?8″ bore
- Internal or external cutting applications
- Modular system footprint can be adapted to a wide range of applications/deck layouts
- Cutting manipulators available to suit all standard casing sizes
- Packer system improves cutting performance through de-watering of the wellbore
- Proprietary Claxton jet technology ensures cutting performance
- Extensive track record – proven on numerous successful campaigns
- Fully NORSOK compliant to Z-015.
SABRE? SUBSEA ABRASIVE CUTTING SYSTEM OVERVIEW
The Claxton range of cutting and recovery equipment has been deployed on over 280 wells reliably, successfully and safely.
Using Claxton’s proprietary high-pressure jet technology, SABRE? accelerates a high pressure jet to transonic speeds – the resulting cutting jet makes light work of composite materials like cemented casings.
Because SABRE? uses naturally occurring cutting components of? the mineral garnet, water and air to cut through multiple well casings without impacting adjacent infrastructure, SABRE? can be classified as ‘low impact’ both environmentally and operationally.
Deployed from a vessel or a platform SABRE? can help to:
- Cut and recover casings simultaneously regardless of annuli loading, eccentricity or content.
- Cuts down to 6.5/8″ ID applications
- Suitable for internal or external cutting applications
- The modular system footprint can be adapted to a wide range of applications and deck layouts. The cutting manipulator also accommodates all common casing sizes.
THE PROBLEM
There are serious doubts about whether King Arthur’s Camelot ever really existed. In contrast, the UK North Sea gas fields and production platform of the same name certainly did, though the evidence has disappeared.
The complete decommissioning of the North Sea Camelot fields and the removal of Camelot Alpha platform began at the start of 2012 with the plugging and abandonment of the fields’ six platform wells. The next stage was severance of the well casings some 5m below the seabed.
THE SOLUTION
The system uses a mixture of air, water and abrasive garnet at up to 1000 bar to cut through the multiple steel casings and any cement within the various annuli. We generally then drill and pin the casings so they can be safely withdrawn in a single operation.
“Part of the process is to prove that we have achieved complete severance within the well; for this, we use a Claxton-designed jacking system to raise the combined casings temporarily and then ease them back down for complete removal later.” This was the process Claxton followed with the Camelot wells, which contained casings ranging in diameter from 95?8″ to 30″, during May and June 2012. The cutting process presented few challenges. The biggest headache for the team was working out how to accommodate the various components of the SABRE? system in the limited deck space available on the small, normally unmanned Camelot platform.
Support beams were used to spread the load of the high-pressure pumps, air compressor, supply tank, mixing system and umbilical required to run the SABRE? system. The beams also provided a secure foundation for the jacks used to confirm the cuts.
The Claxton team also designed a skidding package to shift the equipment between the wells, thereby reducing reliance on the platform crane and shortening the overall time taken for the job.
THE RESULT
“There was much communication with the client, and we jointly planned the job very carefully before we went offshore,” says Leggett. “Once the job started, we had eight people, including supervisors, split into two teams that shuttled back and forth to the platform, thus ensuring virtually 24-hour working.”
In addition to the severance work, Claxton designed and supplied a bespoke lifting cap for the well casing sets. This enabled each set to be easily and safely recovered using a heavy-lift barge in a separate operation carried out after the Claxton team had left the site. Removal of the Camelot platform topsides and jacket is planned for the back end of 2012.
SABRE? is fast becoming the tool of choice for this kind of work because of its performance, flexibility and reliability。
about the company
Claxton combines experienced project engineers, a fast track design and R&D capability with a huge inventory of rapid call off tooling to, simply put, deliver.Across a vast array of drilling riser systems, well abandonment equipment and structures, Claxton delivers pragmatic, safe and reliable solutions to the operating challenges faced by our clients. We have one global team, with a singular mission – to make your project happen.
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