Abstract
Subsea wet gas compressors have been successfully in operation for approximately 5 years. Their use has proven to increase the recovery by approximately 10% and achieve a reliability up to 98%. Further developed and operation of subsea wet gas compression require detailed knowledge of compressor operability and how shift in operational conditions affect the compressor system. The compressors ability to handle wet gas is documented in detail for a gas volume fraction limited down to 0.90. The 4–5 last year of operation proves the wet gas concepts capability. As years pass by, well pressure and production rate declines which causes the compressor operation point to shift towards the high head and low flow (surge) area of the characteristics. In addition, compressor inlet transients increase due to pipe surge (slugs), requiring a robust control system to prevent instabilities, e.g. compressor surge. It is therefore vital to understand how the compressor inlet flow device behaves at different wet operation conditions.
The article documents how a standard dry gas venturi tube behave at different wet gas operation conditions. The venturi is designed according to ISO5167-4 for dry gas conditions and is tested at the low-pressure air water compressor test rig at NTNU. The primary objective of the work has been to visualize the wet flow regime through the transparent venturi tube and to document the wet gas flow rate measurements by means of single-phase meters. The venturi tube is tested in a GMF range from 1 to 0.83 at an air volume flow rate of 1.3m3/s.
