A New Look at Measurement Uncertainty of Multiphase Flow Meters

At present, no standard of presenting multiphase flow meter (MPFM) uncertainties has been accepted by industry. Consequently, vendors' specifications may only indicate velocity and component fraction uncertainties, while customers will typically need to know the overall uncertainty of the hydrocarbon (gas or oil) flow rate. Moreover, comparisons between different meters, meter locations, and metering strategies are difficult without the combined uncertainties of the hydrocarbon measurement. A simple uncertainty analysis (UA) is presented as a means of combining individual measurement uncertainties to determine an overall uncertainty for one of the mixture components, e.g., oil rate. The results are displayed as contour lines of constant oil rate uncertainty on plots of gas fraction versus water cut. Examples illustrate how the uncertainty of oil rate measurement might be reduced by operating the meter at higher pressure, or employing partial separation strategies, and limitations of such strategies.