At the request of Chevron, Versabar Inc. developed the VersaCutter, a subsea cutting tool that provides a safer, more efficient and environmentally friendly way of severing subsea structures such as platforms and pipelines no longer in operation. While removing platforms topside is fairly straightforward, dismantling the jackets or caissons they stand on is not. It typically requires the use of pile jetting, along with mechanical or abrasive cutting devices or explosive charges because materials must be severed a minimum of 15 ft below the mudline. In some cases, operators must excavate below the mudline and send down divers with external cutting devices to perform the task. But these processes present significant challenges and risk to personnel, assets and the environment.
The VersaCutter eliminates the need to jet the mud from around the caisson. Instead, the tool can cleanly cut jackets and conductors 15 ft below the mudline with a minimum of direct personnel. The tool also mitigates environmental damage caused by explosives.
Engineers spent more than two years working on the project, with months of testing at Versabar's Belle Chasse and Houston facilities. The prototype is leading toward development of a larger, more robust system for larger structures. Versabar completed all fabrication for the system in-house.
The only way to test the system was to take it to the Gulf of Mexico and use it on a 250-ton, caisson-mounted topside three miles offshore at the Texas-Louisiana line.
On April 22, after dockside testing was complete, the prototype was deployed to the site. With anchor arms and digger arms working in unison, the cutting wire sawed through mud and cleanly severed the 60-in. caisson, along with both internal and external conductors, a total of eight interfaces of steel and concrete. The entire process took just 10 hours.
General Contractor/Lead Designer Versabar Inc., Houston
Owner Versabar Inc., Belle Chasse, La.