The jackup rig, which weighed more than 30,000 tons, was built on top of supports on a concrete track 20 m (66 ft) from the quayside.
ALE used its own unique, self-propelled skidding system and ballasting system to load-out the jackup rig from the quay onto a floating drydock barge. Seventy-six skid shoes, each equipped with a 650-ton capacity jack, were installed underneath the rig. By extending these cylinders, the load was transferred from the building supports onto the skidding system.
The three-point hydraulic suspension was created in order to control and check the stability of the system during the load-out. The ALE ballast system was installed beside the internal ballast system of the floating drydock itself. This, the contractor said, provided sufficient ballasting capacity for the tide during the load-out and was used to compensate the barge the load was transferred from the skidding system.
As the system is made completely computerized, all parameters such as wind speed, hydraulic pressures, stroke sensors and heel, trim, can be checked from the control room.
ALE’s Supervisor Nico den Engelsen said: “In terms of contingency, usability and safety, I truly believe that this improved skidding system is by far the most complete and competitive in the industry. By using the overview from the control room, we could keep the operation easily within the predetermined limits.
“Speaking on behalf of the team, I can say that we are incredibly proud of the system and how it represents the next level of skidding capabilities. We are yet to reach the limits of the system and look forward to continue to push the boundaries again in future projects.”
Statoil’s Cat- J rig is a fit-for-purpose harsh environment jackup for operations in both surface and subsea wells in the shallow-water segments on the Norwegian continental shelf. Designed to work primarily for drilling and completion of production wells, the rig can operate at water depths from 70 to 150 m (230 to 492 ft) and drill wells down to 10,000 m (32,808 ft).
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