Characterization of Oil/Water Flows in Inclined Pipes
- Serdar Atmaca (Schlumberger) | Cem Sarica (University of Tulsa) | Hong-Quan Zhang (University of Tulsa) | Abdel Salam Al-Sarkhi (King Fahd University)
- Document ID
- Society of Petroleum Engineers
- SPE Projects, Facilities & Construction
- Publication Date
- June 2009
- Document Type
- Journal Paper
- 41 - 46
- 2009. Society of Petroleum Engineers
- 6.5.2 Water use, produced water discharge and disposal, 4.1.9 Tanks and storage systems, 3.1.7 Progressing Cavity Pumps, 4.2 Pipelines, Flowlines and Risers, 4.1.2 Separation and Treating, 5.3.2 Multiphase Flow, 4.3 Flow Assurance, 4.1.5 Processing Equipment, 3.3.1 Production Logging
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Oil/water flow is a common occurrence during production and transportation of petroleum fluids through pipes. Understanding of oil/water pipe flow behaviors is crucial to many applications including design and operation of flow lines and wells, separation, and interpretation of production logs. In this study, the oil/water pipe flow was experimentally investigated for different inclination angles (0°, ±1°, ±2° and -5°). A total of 324 tests were conducted in a 0.0508-m (2-in.) ID 21.1-m (69.6-ft) long test section using tap water and mineral oil with superficial velocities ranging from 0.025 to 1.75 m/s. The experimental results include observations of flow patterns and phase distributions, and measurements of water holdups and pressure gradients. A high-speed video system was used to observe the mixing status between oil and water and to determine the flow patterns at various flow conditions. Quick closing valves were used to measure the phase holdups and to demonstrate the slippage between oil and water with the water cut to water holdup ratio. The experimental results of flow pattern transitions, water holdups, and pressure gradients are compared against predictions of the Zhang and Sarica (2006) model. The model performance is analyzed based on the experimental observations and the modeling considerations. Recommendations are presented for future model improvement.
Two-phase liquid/liquid pipe flow is defined as the simultaneous flow of two immiscible liquids in pipes. Oil/water flow in pipes is a common occurrence in petroleum production, especially for old oil field and for enhanced oil recovery (EOR) with water injection (cold or hot). Moreover, two-phase liquid/liquid flow is common in the process and petrochemical industries. Although the accurate prediction of oil/water flow is essential, oil/water flow in pipes has not been explored as much as gas/liquid flow. Models developed for gas/liquid systems cannot be readily used in liquid/liquid ones due to significant differences between them. The oil/water systems usually have large difference in viscosities, similar densities, and more complex interfacial chemistry compared to gas/liquid systems.
During the simultaneous flow of oil and water, a number of flow patterns can appear ranging from fully separated (or stratified) to fully dispersed ones (Lovick and Angeli 2004). Stratified flow has received more attention during the past decades because of its low phase velocities and well defined interface. On the other hand, fully dispersed flow can be modeled as a single-phase flow provided that the dispersion effective viscosity is properly estimated. There is limited information on the intermediate flow patterns, which lie in between stratified and fully dispersed flows. In this study, the gradual flow pattern transitions from stratified flow to dispersed flow are observed and characterized. The water holdups and pressure gradients are measured and analyzed.
A simple two-fluid oil/water pipe flow model was proposed by Zhang and Sarica (2006) as part of a three-phase unified model. Flat interface was assumed for the stratified oil/water flow. The transition from stratified flow to dispersed flow is based on the balance between the turbulent energy of the continuous phase and the surface free energy of the dispersed phase. The inversion point and effective viscosity of the dispersion are estimated using the Brinkman model (1952). The model predictions of the flow pattern transition, water holdup and pressure gradient are compared with the present experimental results. The model performance under different flow conditions is analyzed and further improvements are recommended.
|File Size||397 KB||Number of Pages||6|
Atmaca, S. 2007. Characterization of Oil/water Flows in Inclined Pipes. MSthesis, University of Tulsa, Tulsa, Oklahoma.
Brinkman, H.C. 1952. Theviscosity of concentrated suspensions and solutions. J. Chem. Phys.20 (4): 571. doi:10.1063/1.1700493.
Lovick, J. and Angeli, P. 2004. Droplet size and velocityprofiles in liquid/liquid horizontal flows. Chem. Eng. Sci.59 (15): 3105-3115. doi:10.1016/j.ces.2004.04.035.
Trallero, J.L. 1995. Oil/water Flow Patterns in Horizontal Pipes. PhDdissertation, University of Tulsa, Tulsa, Oklahoma.
Zhang, H.-Q., and Sarica, C. 2006. Unified Modeling of Gas/Oil/WaterPipe Flow--Basic Approaches and Preliminary Validation. SPE Proj Fac& Const 1 (2): 1-7. SPE-95749-PA. doi:10.2118/95749-PA.