Mass Fraction Measurements in Controlled Oil-Water Flows Using Noninvasive Ultrasonic Sensors

Controlled flow rate tests using mixtures of crude oil and water at different mass fractions were carried out in a flow loop at the University of Tulsa. A noninvasive acoustic method developed at the Los Alamos National Laboratory (LANL) was applied to calculate the mass and volume fractions of oil and water in the mixed two-phase flow by measuring the speed of sound through the composite fluid mixture along with the instantaneous temperature. The densities and sound speeds in each fluid component were obtained in advance for calibration at various temperatures, and the fitting coefficients were used in the final algorithm. In this paper, we present composition measurement results using the acoustic technique from LANL for different mixture ratios of crude oil and water and at varying flow rates and a comparison of the results from the acoustics-based method with those from Coriolis meters that measured individual mass flow rates prior to mixing. The mean difference between the two metering techniques was observed to be less than 1.4% by weight and is dependent on the total flow rates. A Monte Carlo analysis of the error due to calibration uncertainty has also been included.