The Challenges of Multiphase Flow Metering: Today and Beyond

Abstract

Since the early 1990’s, when the first commercial meters started to appear, Multiphase Flow Metering (MFM) has grown from being an area of R&D to representing a discipline in its own right within the oil and gas industry. The total figure for MFM installations worldwide is now over 1,800. Field applications include production optimisation, wet gas metering, mobile well testing and production allocation. However, MFM has not yet achieved its full potential. Despite an impressive improvement in the reliability of sensors and mechanical parts (particularly for subsea installations) over the past few years, there remain unresolved questions regarding the accuracy and range of applicability of today’s MFM technology. There is also a tendency to forget the complexity of multiphase flow and to evaluate the overall performance of a MFM as a “black box”, often neglecting all the possible uncertainties that are inherent in each individual measurement solutions. This paper reviews the inherent limitations of some classical MFM techniques. It highlights the impact of instruments rangeability, empirical correlations for pressure drop devices and fluids characterisation on the error propagation analysis in the “black box”. It also provides a comprehensive review of wet gas definitions for the oil and gas industry. Several attempts have been made to define “wet gas” for the purpose of metering streams at high gas-volume-fractions, but a single definition of wet gas still does not exist. The measurement of multiphase flows presents unique challenges that have not yet been fully resolved. However, the challenges are exciting and the authors have no doubts that new milestones will soon be set in this area. Today’s MFM technology has already become one piece of the optimised production system jigsaw. MFM has succeeded in fitting with other technologies toward global field-wide solutions. The ideal MFM of the future is one that provides unambiguous measurements of key parameters from which the flow rates can be deduced independently from flow regimes and fluid properties.