Investigations of phase inversion and frictional pressure gradients in upward and downward oil–water flow in vertical pipes

• Published in: International journal of multiphase flow Vol. 36; no. 11; pp. 930 - 939
• Main Authors: Xu, Jing-yu, Li, Dong-hui, Guo, Jun, Wu, Ying-xiang
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.11.2010; Elsevier
• Subjects: Applied sciences; Crude oil, natural gas and petroleum products; Crude oil, natural gas, oil shales producing equipements and methods; Density; Dispersion; Effective mixture viscosity; Energy; Exact sciences and technology; Frictional pressure gradient; Fuels; Liquids; Mathematical models; Oil–water vertical flow; Phase inversion; Phase shift; Pipe; Pressure gradients; Prospecting and production of crude oil, natural gas, oil shales and tar sands; Phase inversion; Frictional pressure gradient; Oil–water vertical flow; Effective mixture viscosity; Two phase flow; Oil water emulsion; Phase reversal; Pressure gradient; Experimental study; Oil well; Vertical tube; Effective viscosity; Flow regime; Friction coefficient; Oil-water vertical flow
• ISSN: 0301-9322; 1879-3533
• DOI: 10.1016/j.ijmultiphaseflow.2010.08.007

The present study has attempted to investigate phase inversion and frictional pressure gradients during simultaneous vertical flow of oil and water two-phase through upward and downward pipes. The liquids selected were white oil (44 mPa s viscosity and 860 kg/m 3 density) and water. The measurements were made for phase velocities varying from 0 to 1.24 m/s for water and from 0 to 1.87 m/s for oil, respectively. Experiments were carried either by keeping the mixture velocity constant and increasing the dispersed phase fraction or by keeping the continuous phase superficial velocity constant and increasing the dispersed phase superficial velocity. From the experimental results, it is shown that the frictional pressure gradient reaches to its lower value at the phase inversion point in this work. The points of phase inversion are always close to an input oil fraction of 0.8 for upward flow and of 0.75 for downward flow, respectively. A few models published in the literature are used to predict the phase inversion point and to compare the results with available experimental data. Suitable methods are suggested to predict the critical oil holdup at phase inversion based on the different viscosity ratio ranges. Furthermore, the frictional pressure gradient is analyzed with several suitable theoretical models according to the existing flow patterns. The analysis reveals that both the theoretical curves and the experimental data exhibit the same trend and the overall agreement of predicted values with experimental data is good, especially for a high oil fraction.