With the increasing need to operate Subsea Production Systems (SPS) in harsh environments, comes a need to produce with long distances (step out) from shore and in potentially deep water applications from the process plants, eliminating the need for manned offshore production units. This presents challenges for the flow assurance aspects to maintain high production regularity, asset integrity and thereby demands highly reliable control systems to ensure this happens. The Snøhvit project in the Barents Sea is a milestone in subsea oil and gas development, with a record breaking offset (147Km) and all subsea facilities tied-back to shore, without any surface-piercing structures such as platform or floating production facilities, with a consequent dramatic improvement in environmental impact. GE has further qualified the fibre optical control systems to 220Km. A similar control system is also now to be used for the Gorgon/Janz development. It is also envisaged that these systems can be utilised in offshore Tanzania.

The key flow assurance aspects to take into consideration for such a system are:

  • Handling different operating regimes of transporting of multiphase fluids over the field life

  • Transporting High viscous fluids at low pressure or temperature addressing Wax, Hydrates formations, mitigations and remediation

  • Strategies to increase the operating envelope including shutdown or restart operations and the impact of operating modes on the production and system integrity

  • Flow assurance challenges due to uneven seabed

In the recent years there has been increased focus on the aim for both standardisation and simplification, such that there has been new developments of new applications such as virtual flow meters. GE has developed this as part of the flow assurance aspect along with potential SMART system applications.

The presentation focuses on the technical and logistical achievements in executing this ultra-long offset subsea-to-beach project and the interaction with flow assurance requirements.

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