Deepwater TCMS Mooring and Production System for Marginal Fields

Mooring Systems Ltd has announced a tricatenary mooring and riser system for floating production, storage and offtake (FPSO) vessels in marginal, deepwater and ultra-deepwater, oil and gas fields. The deepwater tricatenary mooring system (TCMS) provides a simpler, more cost-effective mooring, and requires less FPSO modification, than traditional deepwater mooring systems.

Deepwater TCMS comprises three synthetic fibre rope mooring lines radiating at equal angles from a connecting node below the sea surface, with a mooring pendant rising from the node to the bow of the moored FPSO. Flowline risers are fed through a guide frame within the pendant to on-board processing plant. To cope with wave and wind movements offshore, the TCMS allows the FPSO to weathervane.

In the event of adverse weather conditions, the bow-mounted riser production tower is fully disconnectable and can be abandoned to 70m water depth while the FPSO sails to a safe port. When the FPSO returns, and is on station, the tower is retrieved and reconnected to the bow of the vessel.

Deepwater Marginal Field Mooring and Production

Deepwater TCMS is designed to offer independent operators an alternative to conventional deepwater mooring systems which are complex and expensive to deploy in marginal fields at water depths greater than 1,000m. In addition, they often require substantial modifications to the FPSO such as the addition of a mooring turret. In a marginal field, a turret capable of handling a small number of risers is overkill compared with a deepwater TCMS designed for four or five risers, which is more practical and quicker to deploy.

“Since the late 1990s TCMS systems have provided a cost-effective mooring solution in marginal shallow water fields. The deepwater TCMS builds on this success and experience to give independent operators a method of maximising the profitability of deepwater marginal fields,” says Mooring Systems, general manager, Doug Davidson.

Deepwater TCMS builds on the success of the shallow water, tricatenary mooring system where the simplicity and speed of mooring line deployment, and the ease of vessel bow modification, has led to its use on a number of FPSO and floating storage vessels.

For more information on TCMS in deepwater and ultra-deepwater, marginal fields contact Mooring Systems Ltd call +44 (0)1224 624666, email: and web site:


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