Diamond wire saw cutting to assist decommissioning


Maersk Supply Service contracted Underwater Cutting Solutions (UCS) to assist with the decommissioning of the Janice, James and Leadon fields.

With the towheads and mid-line structure requiring to be cut free from the bundles in the Leadon field, UCS commissioned a new size of diamond wire saw to effectively sever carrier pipes containing multi-string internals.

This 56” diamond wire saw was required to cut through Bundle Section A (42.5” OD carrier with a 46” OD carrier transition) and Bundle Section B (47.5” OD carrier plus 51” OD carrier transition). With the carrier pipe consisting of seven internal elements as well as a cable tray, considerable cutting performance was required.

The solution

Given that UCS had pioneered a new size of diamond wire saw specifically for this project, test cuts were performed at UCS headquarters using pipe test bundles supplied by Maersk Supply Service.

Results

The 51” x 30mm WT outer carrier, consisting of seven internal pipes and a length of flat bar, was successfully cut in less than two hours (1hr 53min). Having proved itself with an identical test specimen, the 56” diamond wire saw was soon dispatched offshore to complete the project.

The DWS was deployed by vessel crane with ROV assistance, expertly locating the tool onto the cut location. Once at a depth of -145m, UCS technicians controlled the tool from topside via the Solenoid Control System. On average, cutting operations took only 97 minutes for each of the six bundle cuts, proving the suitability of this UCS-engineered solution for large bundle sizes.