The Ningaloo Vision Upgrade Project comprises modifications to the Ningaloo Vision Floating Production, Storage and Offloading vessel (FPSO), which is operating on the Van Gogh oilfield, and development of the neighbouring Coniston and Novara oilfields which will be tied into the existing Van Gogh subsea infrastructure.
The Ningaloo Vision is serviced by two 100% capacity fire pumping systems, each system consisting of a lift pump and a pressure pump. The pressure delivered by these pumps is now about 1 bar lower than their original rated pressure at the rated capacity. Investigations to remedy this drop in pressure have improved performance but have not been able to achieve design capacity.
PDC was requested to perform a pipe network analysis, to determine the impact of the lower pressure, for the rate determining case of Zone 14 (Module 1A) plus adjacent modules, foam system and hydrants.
The scope of the report was to:
Confirm that the analytical model aligns with current fire system test data
Provide calculated flows for modules & components at current pumping capability
Propose modifications to achieve minimum pressures/flow rates to all nozzles at current pumping capability
Determine the minimum test pressure reading to achieve the minimum required flows.
Resulting from the issue of drafts of the report, PDC was subsequently requested to investigate:
modifications necessary to achieve the minimum required flow at all nozzles in zone 16 (module 2)
the effect of the lower pressure on zones 4, 10 & 17 and necessary modifications to orifice plates
the effect of the lower pressure on zones 9, 19, 21 & 22 and necessary modifications
The fire fighting system is extensive and covers 22 zones; twelve of which are serviced by firewater & foam.
The project required re-modelling of the majority of existing pipework.
The analysis enabled limiting the necessary changes to modifying orifice plates and changing a minimal number of spray nozzles in affected areas.