Numerical modelling of two-phase oil–water flow patterns in a subsea pipeline

2016 ◽  
Vol 115 ◽  
pp. 135-148 ◽  
Author(s):  
Hassan Pouraria ◽  
Jung Kwan Seo ◽  
Jeom Kee Paik
Author(s):  
S. Alireza Hojati ◽  
Pedram Hanafizadeh

The flow patterns in two phase and multi-phase flows is a significant factor which influences many other parameters such as drag force, drag coefficient and pressure drop in pipe lines. One of the major streams in the gas and oil industries is oil-water two phase flow. The main flow patterns in oil-water flows are bubbly, slug, dual continuous, stratified and annular. In the present work flow patterns in two phase oil-water flow were investigated in a 0.5in diameter pipe with length of 2m. 3D simulation was used for this pipe and six types of mesh grid were used to investigate mesh independency of the simulation. The proposed numerical analyses were performed by a CFD package which is based both on volume of fluid (VOF) and Eulerian-Eulerian methods. The results showed that some flow patterns can be simulated better with VOF method and some other maybe in Eulerian-Eulerian method, so these two methods were compared with together for all flow patterns. The flow patterns may be a function of many parameters in flow. One of the important parameter which may affect flow patterns in pipe line is pipe inclination angle; therefore flow patterns in the different pipe inclination angles were investigated in two phase oil-water flow. The range of inclinations has been varied between −45 to +45 degree about the horizon. In the presented simulation oil is mixed with water via a circular hole at center of the pipe, the ratio of oil surface to water surface at entrance is 2/3 so water phase was considered as the main phase. Flow patterns were investigated for every angle of pipe and numerical results were compared with available experimental data for verification. Also the flow patterns simulated by numerical approaches were compared with available flow regime maps in the previous literatures. Finally, effect of pipe inclination angle and flow patterns on the pressure loss were investigated comprehensively.


1998 ◽  
Vol 120 (1) ◽  
pp. 8-14 ◽  
Author(s):  
J. G. Flores ◽  
C. Sarica ◽  
T. X. Chen ◽  
J. P. Brill

Two-phase flow of oil and water is commonly observed in wellbores, and its behavior under a wide range of flow conditions and inclination angles constitutes a relevant unresolved issue for the petroleum industry. Among the most significant applications of oil-water flow in wellbores are production optimization, production string selection, production logging interpretation, down-hole metering, and artificial lift design and modeling. In this study, oil-water flow in vertical and inclined pipes has been investigated theoretically and experimentally. The data are acquired in a transparent test section (0.0508 m i.d., 15.3 m long) using a mineral oil and water (ρo/ρw = 0.85, μo/μw = 20.0 & σo−w = 33.5 dyne/cm at 32.22°C). The tests covered inclination angles of 90, 75, 60, and 45 deg from horizontal. The holdup and pressure drop behaviors are strongly affected by oil-water flow patterns and inclination angle. Oil-water flows have been grouped into two major categories based on the status of the continuous phase, including water-dominated and oil-dominated flow patterns. Water-dominated flow patterns generally showed significant slippage, but relatively low frictional pressure gradients. In contrast, oil-dominated flow patterns showed negligible slippage, but significantly large frictional pressure gradients. A new mechanistic model is proposed to predict the water holdup in vertical wellbores based on a drift-flux approach. The drift flux model was found to be adequate to calculate the holdup for high slippage flow patterns. New closure relationships for the two-phase friction factor for oil-dominated and water-dominated flow patterns are also proposed.


Author(s):  
Hai-Yuan Yao ◽  
Jing Gong

In this paper, an experimental research on the oil-water liquid-liquid two-phase flow patterns and their transitions in horizontal pipes are carried out. According to online oil-water flow structures and the analysis of pressure drop signals., different flow patterns are defined and distinguished. A new classification for oil-water flow patterns is proposed. The flow pattern maps are obtained from the experimental data, and the factors affecting the transition mechanism of different flow regimes are discussed. In addition, some semi-theoretical criteria for the transition between different flow patterns are proposed. Especially, an accurate model is developed to predict the critical conditions for phase inversion. Comparisons of the proposed criteria with other experimental data show reasonable agreements.


Author(s):  
Hooman Foroughi ◽  
Masahiro Kawaji

The flow characteristics of a highly viscous oil and water mixture in a circular microchannel have been investigated. Water and silicone oil with a viscosity of 863 mPa.s were injected into a fused silica microchannel with a diameter of 250 μm. Before each experiment, the microchannel was initially saturated with either oil or water. In the initially oil-saturated case, different liquid-liquid flow patterns were observed and classified over a wide range of oil and water flow rates. As a special case, the flow of water at zero oil flow rate in a microchannel initially filled with silicone oil was also studied. When the microchannel was initially saturated with water, the oil formed a jet in water at the injection point but developed an instability at the oil-water interface downstream and eventually broke up into droplets.


SPE Journal ◽  
2016 ◽  
Vol 22 (01) ◽  
pp. 339-352 ◽  
Author(s):  
A.. Abubakar ◽  
Y.. Al-Wahaibi ◽  
T.. Al-Wahaibi ◽  
A.. Al-Hashmi ◽  
A.. Al-Ajmi ◽  
...  

Summary Experimental investigations of flow patterns and pressure gradients of oil/water flow with and without drag-reducing polymer (DRP) were carried out in horizontal and upward-inclined acrylic pipe of 30.6-mm inner diameter (ID). The oil/water flow conditions of 0.1- to 1.6-m/s mixture velocities and 0.05–0.9 input oil-volume fractions were used, and 2,000 ppm master solution of the water-soluble DRP was prepared and injected at controlled flow rates to provide 40 ppm of the DRP in the water phase at the test section. The flow patterns at the water-continuous flows were affected by the DRP, whereas there were no tangible effects of the DRP at the oil-continuous flow regions. The upward inclinations shifted the boundaries between stratified flows and dual continuous flows, and the boundaries between dual continuous flows and water-continuous flows to lower mixture velocities. This means that the inclinations increased the rate of dispersions. The frictional pressure gradients for both with and without DRP slightly decreased with inclinations especially at low mixture velocities, whereas the significant increases in the total pressure gradients with the inclinations were more pronounced at low mixture velocities. The inclinations did not have a major effect on the drag reductions by the DRP at the high mixture velocities and low-input oil-volume fractions where the highest drag reductions recorded were 64% at 0° inclination and 62% at both + 5° and +10° inclinations. However, the inclinations increased the drag reductions as the input oil-volume fractions were increased before phase-inversion points.


2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Wei Wang ◽  
Wei Cheng ◽  
Kai Li ◽  
Chen Lou ◽  
Jing Gong

A systematic work on the prediction of flow patterns transition of the oil-water two-phase flows is carried out under a wide range of oil phase viscosities, where four main flow regimes are considered including stratified, dispersed, core-annular, and intermittent flow. For oil with a relatively low viscosity, VKH criterion is considered for the stability of stratified flow, and critical drop size model is distinguished for the transition of o/w and w/o dispersed flow. For oil with a high viscousity, boundaries of core-annular flow are based on criteria proposed by Bannwart and Strazza et al. and neutral stability law ignoring that the velocity of the viscous phase is introduced for stratified flow. Comparisons between predictions and quantities of available data in both low and high viscosity oil-water flow from literatures show a good agreement. The framework provides extensive information about flow patterns transition of oil-water two-phase flow for industrial application.


Author(s):  
Jose Zaghloul ◽  
Michael Adewumi ◽  
M. Thaddeus Ityokumbul

The transport of unprocessed gas streams in production and gathering pipelines is becoming more attractive for new developments, particularly those is less friendly enviroments such as deep offshore locations. Transporting gas, oil, and water together from wells in satellite fields to existing processing facilities reduces the investments required for expanding production. However, engineers often face several problems when designing these systems. These problems include reduced flow capacity, corrosion, emulsion, asphaltene or wax deposition, and hydrate formation. Engineers need a tool to understand how the fluids travel together, quantify the flow reduction in the pipe, and determine where, how much, and the type of liquid that would from in a pipe. The present work provides a fundamental understanding of the thermodynamics and hydrodynamic mechanisms of this type of flow. We present a model that couples complex hydrodynamic and thermodynamic models for describing the behavior of fluids traveling in near-horizontal pipes. The model incorporates: • A hydrodynamic formulation for three-phase flow in pipes. • A thermodynamic model capable of performing two-phase and three-phase flow calculations in an accurate, fast and reliable manner. • A new theoretical approach for determining flow pattern transitions in three-phase (gas-oil-water) flow, and closure models that effectively handle different three-phase flow patterns and their transitions. The unified two-fluid model developed herein is demonstrated to be capable of handling systems exhibiting two-phase (gas-water and gas-oil) and three-phase (gas-oil-water) flow. Model predictions were compared against field and experimental data with excellent matches. The hydrodynamic model allows: 1) the determination of flow reduction due to the condensation of liquid(s) in the pipe, 2) assessment of the potential for forming substances that might affect the integrity of the pipe, and 3) evaluation of the possible measures for improving the deliverability of the pipeline.


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