Using sound speed to determine volume fractions in a two-phase flow.

Abstract

This paper presents a method of determining the volume fractions of two immiscible fluids in a two-phase flow by measuring the speed of sound through the composite fluid and the instantaneous temperature. Two separate algorithms are developed, based on earlier work by Urick [J. Appl. Phys. (1947)] and & Toksoz [Geophys (1974)]. The main difference between these two models is the representation of the composite density as a function of the individual densities; the former uses a linear rule-of-mixtures approach, while the latter uses a non-linear formulation. Both methods lead to a quadratic equation, the root of which yields the volume fraction (φ), subject to the condition 0⩽φ⩽1. We present results of a study with mixtures of crude oil and processed water, and a comparison of our results with a Coriolis meter. The fluid densities and sound speeds are calibrated at various temperatures for each fluid component, and the coefficients are used in the final algorithm. Analytical and numerical studies of sensitivity of the calculated volume fraction to temperature changes are also presented. [This work was supported by Chevron USA.]