Ultrasonic Doppler velocimetry and imaging in two-phase pipe flow

The objective of this study was to determine the feasibility of using ultrasonics to measure fluid velocities and to image the phase distribution in two-phase pipe flow. Experiments were performed in air-water and oil-water flow regimes, and with the pipe in both vertical and inclined positions. The data acquisition and analysis system was based on a medical ultrasound instrument, modified as needed, and a microcomputer. Measurements were made in the 42 ft. long by 7.25 in. i.d. pipe of the Multiphase Flow Loop in the Department of Petroleum Engineering of the University of Texas at Austin. This facility can simulate a wide range of flow conditions due to its rate capabilities and its continuously variable inclination.;The ultrasonic Doppler measurements gave reasonable qualitative results in all regimes of which the flow loop is capable. The Doppler frequency was generally proportional to the velocity of the light phase, although the calculated velocities tended to underestimate the flow rate. The total flow rate of both phases varied from 60 m;Bubbles were clearly visible in images made in air-water bubble flow regimes at low void fractions. A technique was developed to estimate axial bubble velocity using the ultrasonic image. Also, gravity segregation of the phases in an inclined pipe could be discerned. The clarity of images made in oil-water flows varied considerably; the bubbles were visible in some bubble flow regimes and not visible in others.;The results obtained indicate the ultrasonic measurements can be used as a tool in the study of two-phase pipe flow and could provide valuable information about downhole flow characteristics in an oil or gas well. Directions for further work include the study of the effect of frequency on ultrasonic tone burst propagation in two phase flows, the development of improved transforms to calculate velocity from Doppler frequency, and the determination of optimal focusing parameters and image processing techniques for enhancing image quality.