Decommissioning of two single point mooring (SPM) Calm Buoys
Project overview
Project name
Decommissioning of two single point mooring (SPM) Calm Buoys
Location
Gulf of Thailand
Water depth
70 m water depth
Solution
Decommissioning and safe transport of aging assets
Intermoor, Acteon’s Moorings and Anchors business line, was commissioned by a global energy operator in Southeast Asia to decommission two Single Point Mooring (SPM) Calm Buoy Systems and their associated subsea infrastructure.
Ensuring continuity of production
The decommissioning and safe transport of the aging assets took place while the live pipeline remained connected to a subsea manifold, avoiding a production shutdown that would have affected multiple platforms in the field. The project had to be completed under a strict deadline to ensure the client’s commitment to the government and the receiving operator could be fulfilled.
End-to-end support
We provided end-to-end support, seamlessly coordinating all aspects of the decommissioning process from marine spread charter and management, equipment and tools selections and provision and management of experienced personnel. We coordinated communication between all contractors, allowing for an efficient and safe operation.
The campaign involved the removal of SPM1 and SPM2 with their associated subsea components:
SPM1
- Foam injection in all buoy tanks
- Disconnection and recovery of 2x 8” submarine Hoses and buoyancy tank
- Disconnection and recovery of 6x mooring chains (3x 102 mm and 3x 111 mm)
- Towing of SPM1 to a dedicated handover yard in Thailand
- Cutting and removal of mooring piles – 5 m below mudline
- Handover of all recovered subsea assets to a dedicated handover yard in Thailand
SPM2
- Foam injection in all buoy tanks
- Disconnection and recovery of 10” flexible riser
- Disconnection and recovery of 6x mooring chains (3x 102 mm and 3x 111 mm)
- Towing of SPM2 to a dedicated handover yard in Thailand
- Disconnection and recovery of Mid Water Arch (MWA) and Gravity Base
- Handover of all recovered subsea assets to a dedicated handover yard in Thailand
In addition to meticulous planning and effective coordination, our ability to swiftly adapt and implement contingency plans was key to overcoming unexpected challenges—such as water ingress and detached hoses—caused by the aging infrastructure, ensuring smooth and efficient operations throughout. We also put an efficient plan in place to optimise the deck layout to reduce the need for additional mobilisations to perform multiple scopes. Ultimately, the driving support vessel (DSV) was only required to mobilise twice.
Innovations in action
We ensured environmental stewardship by employing a dedicated waste management expert to manage all activities regarding waste handling, especially for the flexible riser and hose. This specialist was integral in implementing stringent waste management protocols, ensuring that all materials were handled, stored, and disposed of in accordance with the highest environmental standards.
- Marine growth was cleaned beforehand and all subsea assets handed over were cleaned
- An approved procedure was implemented, along with the required personal protective equipment (PPE), gas detectors and trained personnel.
- By anticipating potential contingencies, the team was prepared to respond swiftly and effectively to any unexpected challenges, mitigating the risk of environmental harm. This approach not only safeguarded the surrounding marine ecosystem but also reinforced our client’s reputation for responsible operations.
The result
The successful decommissioning of two Single Point Mooring CALM Buoy Systems in the Gulf of Thailand further reinforces Intermoor’s proven expertise and capability in managing complex offshore projects, building on a strong track record of similar operations. Despite challenges such as maintaining live pipeline connections and dealing with aging infrastructure, we not only met the client’s objectives but also highlighted our ability to adapt and overcome unforeseen difficulties, reinforcing our reputation as a reliable partner in the offshore industry.
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