FPSO optimisation tool

The operator of the FPSO was facing a new opportunity to utilize the existing process capacity both on the gas handling and liquid handling. In addition, accessible space and weight on the process area could be another challenge.

This opportunity involved two challenges, one more tricky than the other.

• Different ownership, hence, allocation issue.
• The new oil field will create compatibility issues.

The first challenge might be addressed using multi-phase metering which did not challenged the space and weight constrains.

The second challenge might be solved by use of the test separator processing the new tie back, but frequent use of this test separator for well testing, hence stop in production with the consequences for both the economy and well behaviour, turned out to be a showstopper.

The compatibility issue required a dedicated separator.

• Installation of a two parallel DPS configuration fit for the 30.000 BPD new process flow, hence reduced weight and space requirements. If a conventional separator is installed it needed to be of similar size as the existing inlet separator due to retention time requirement on the level control system. The DPS can be compared to a pipeline without this requirement.
• The gas directed to the gas handling system upstream cooler and scrubber
• The water from the DPS system directed to system 44, produced water treatment, using the existing hydrocyclone and downstream control valve. The existing control valve is thereby used to control the interface in the DPS.
• The dry oil from the DPS is directed to the second stage separator for further stabilisation

• The selected DPS system could be installed without additional investment on the fire and the flare system since the liquid volume in the DPS system is small.

  The allocation could be easily accessed on the separated flows from the DPS. The typical slugging issue the make multi-phase metering a problem does not exist when the DPS system is selected. The gas Harp suppress the slug and provide a more stable flow for all phases and metering more accurate.

  Installation can be done using the FPSO crane since the weight is low.

  No need of safety valves or burst discs since the DPS can easily be designed to shut in pressure, another benefit using small diameters and pipe code. Spec.brake (pressure differentiation) can be applied downstream the DPS if selected.

  The hook up operation become easy since less pipe work is needed. Less manhours offshore.