Flow profile effects due to pipe geometry in an export gas metering station - Analysis by CFD simulations

This paper describes a computational fluid dynamics (CFD) analysis that was performed to understand the observed characteristics in a gas export metering station at an offshore installation on the Norwegian Continental Shelf. The metering station has two parallel metering runs, each equipped with an ultrasonic flow meter. The metering station has flow conditioners installed according to recommended standards. The header upstream of the metering lines has T-bends at the end sections. Observations in field showed some peculiarities and instabilities in the flow that needed to be investigated in more details. Through CFD analysis it is shown that the T-bends in the upstream header can cause severe distortions of the flow profiles. It is demonstrated that both the pipe geometry upstream the inlet header and the geometry of the inlet header itself may affect the flow profile in the flow meters. The scope of this paper is to investigate effects on the flow measurement due to pipe geometry by use of CFD. In order to investigate which parts of the geometry that causes the different effects, various variants of the piping have been analysed.