Enhancements in Fraction Measurements and Flow Modeling for Multiphase Flowmeters
Multiphase flowmeters (MPFMs) have been used since the early 1990's in
the oil and gas industry and have gained acceptance in many environments. They
have been considered the primary metering option for a wide range of
applications - from heavy oil to wet gas. The combination of operational
benefits, measurment robustness, demonstrable accuracy, and auditability has
improved their status from new, unproven technology to that of the premium
mainstream metering option.
With more than a decade of experience acquired using a combination
venturi and gamma-ray multiphase flowmeteres, further gains in measuremnet
quality and operational robustness have been achieved. We will illustrate how
enhancements in fraction measurements using multi-energy gamma ray attenuation
and a more comprehensive analysis of the gamma-ray spectrum have been developed
and implemented to provide better measurement accuracy and stability, leading
to enhanced performances in multiphase flow measurements.
Another area of improvement that has been pursued is in the field of
modeling of multiphase flows through a venturi. Historically, single-phase flow
equations have been used, being adapted to multiphase flows by semi-empirical
means to account for their complexity. While such models have proven robust for
most standard applications, they can reach some limitations in particular
conditions. We will present how a more dynamic model that considers the nature
of the flow has led to improved accuracy of multiphase flow measurements.
We present the scientific basis for the new enhancements as well as
illustrate the accuracy gains achieved based on hundreds of flow loop test
points, ultimately leading to the quantification of the accuracy gains obtained
through those technological improvements.