Fugro was contracted by Chevron North Sea Ltd to provide the necessary engineering, planning and resources to conduct a Xmas tree installation in the Alder Field, UK North Sea. The tree was to be installed using the ROV support vessel Fugro Symphony.
Due to a challenging project timescale, linked to the programme of the drilling rig in the field, Fugro was able to plan and execute the whole job within a compressed timeframe.
Our in-house engineering and project management teams were allocated to the project and conducted all the required project engineering and procurement activities. This consisted of writing offshore installation procedures, engineering and procurement of all rigging and installation aids and seafastening design calculations. An installation analysis was conducted and used to determine the operational weather limitations for the work. The engineering team involved in the onshore preparation of the project also went offshore for the execution phase, ensuring continuity of knowledge, which contributed to the successful operation.
All Fugro engineering documents were signed off by a third party surveyor prior to the mobilisation commencing. The 150 tonne active heave compensated crane on board the vessel was used to deploy the tree and land out on the pre-installed Tubing Head Spool (THS) on the well in approximately 150 m water depth. Due to the weight of the Xmas tree, (approx. 61 tonnes) specialist ROV-friendly rigging was sourced to enable the ROV to safely disconnect the tree after installation.
After landing the Xmas tree, various commissioning activities were required. These involved the deployment of a surface powered test hose to conduct pressure tests on the tree connectors. The ROV was used to connect the test hose to the tree, and to undertake various valve and hot stab operations.
Dual Fugro FCV 3000 work-class ROVs were used in tandem at various stages of the operation to ensure safe execution of the task. No damage to equipment or assets occurred.
With the execution of this project we demonstrated that an activity traditionally conducted by drill rigs can be safely executed in the North Sea by an ROV support vessel.
This capability can provide cost and schedule efficiencies whilst maintaining safe operations for operators by reducing the reliance on drilling rigs for such activities.