Characterization of Oil/Water Flows in Horizontal Pipes

Abstract

Summary The dynamic characteristics of oil/water flow systems have not been understood fully. The need for improved designing methods has led researchers toward its continuous investigation. The objective of this study was to characterize oil/water flow through experimental data. The tests were conducted in a 2-in. horizontal test section using tap water and mineral oil (density = 0.85 g/cm3 and viscosity =15 cp), with superficial velocities ranging from 0.025 to 1.75 m/s. Data were acquired on flow patterns, pressure drop, phase fraction, and droplet size as a function of flow patterns and were used in characterization of the flow and performance evaluation of an oil/water model. A high-speed video camera was used to identify flow patterns and measure droplets, and ten conductivity probes were used to obtain phase distributions. This paper provides new experimental data on pressure drop, holdup, phase distribution, and droplet-size distribution in oil/water flows that can lead to better modeling and design of dispersed systems. Moreover, the new data provide new information on droplet sizes that can have significant impact on separator design. Data comparisons were performed against the data of Trallero (1996). Three probabilistic distributions were tested for fully dispersed flows. A Sauter mean-diameter (SMD) analysis was conducted across the pipe diameter. Droplet-size data were used to evaluate existing models such as Hinze (1955), Kubie and Gardner (1977), Angeli and Hewitt (2000), and Kouba (2003). An empirical correlation to predict the SMD profile of droplets across the pipe cross section was developed for flow pattern of dispersed oil in water (o/w) and water. Log-normal distribution was the best probabilistic distribution for representing the data for fully dispersed systems. The empirical correlation gave acceptable results. More data are needed to validate the results. Model comparisons revealed that none of the models could represent the experimental data accurately. This paper provides significant insight into oil/water flows in horizontal pipes. The results are significant for the design of pipelines and separators. Moreover, the interpretation of production logs in horizontal wells relies heavily on the flow behavior.