This paper will address the analysis carried out in order to understand and correct flow meter effects on the Gjøa gas export metering station.

The metering station consists of two parallel metering tubes, each equipped with amultipath ultrasonic flow meter with an upstream flow conditioner. The header

upstream of the two metering tubes has T-bends at the end sections. Through Computational Fluid Dynamics (CFD) it will be shown that the T-bends in the upstream

header can cause severe distortions of the flow profiles, and that the positioning of the flow conditioners can be essential for preventing flow instabilities. It will be

demonstrated that both the pipe geometry upstream the inlet header and the geometryof the inlet header itself may affect the flow instability through the flow meters. The

results will to a large extent explain the effectsfound in practice.

Furthermore, it will be demonstrated how errors in the meter configuration file can affect the meter performance, even in cases where flow calibration has been carried

out successfully.