  A multiphase flowmeter (MPFM) is used in the upstream oil and gas industry
for continuous, in-line, real-time, oil-gas-water flow measurement without
fluid separation. An MPFM typically consists of phase-fraction (holdup) and
velocity (or flow rate) measurements. It is desirable to have homogeneous flow
at the measurement location so that the phase-fraction measurement is
representative. A horizontal blind-tee pipe-section is often installed to
homogenize flow in the downstream vertical Venturi-based flowmeters; however,
little information is available on the effect of horizontal blind-tee depth
(HBD) on flow homogeneity. In addition, the Venturi vertical entrance length
(VEL) leading to the Venturi inlet from the horizontal blind-tee outlet is
another design parameter that may potentially affect the downstream phase
distribution. The phase-fraction measurement principle requires liquid
properties (e.g. water salinity). The local liquid richness makes the
horizontal blind-tee an ideal location for measuring liquid properties;
however, an excessive HBD may affect the reliability of the measurements of
liquid properties, because local vortices may degrade liquid measurement
representativeness if the local liquid velocity is too low. This study uses a
computational fluid dynamics approach to evaluate the effect of HBD and VEL on
multiphase flow measurement, including the Venturi differential-pressure, the
Venturi inlet and the throat phase-fraction, and the local liquid-property at
the end of a horizontal blind-tee. The computational results are validated with
experimental data collected in a multiphase flow facility. Appropriate HBD and
VEL are recommended.
