Variation of Flow Regimes in +2 Degree Inclined Wet Gas Environments and Drag Reduction

2006 ◽  
Author(s):  
Cheolho Kang ◽  
Parimal More
Keyword(s):  
Pressure Gradient ◽  
Gas Phase ◽  
Slug Flow ◽  
Flow Characteristics ◽  
Phase Variation ◽  
Flow Patterns ◽  
Upward Flow ◽  
Wet Gas ◽  
Wave Forms ◽  
Flow Improver

Experiments were carried out to examine the study of flow patterns and the performance of drag reducing agents in a 40 m long, 10.16 cm diameter, + 2 degree inclined wet gas pipeline environments. Superficial liquid velocities ranging from 0.03 to 0.1 m/s and gas velocities from 2 to 10 m/s were investigated with the commercial DRA concentration of 0, 25 and 50 ppm. Light viscosity oil was used as the liquid phase and carbon dioxide was used as the gas phase. Variation of flow patterns in horizontal and +2 degree pipes are reported in this paper. The effect of inclinations on the pressure gradient is also presented. The stratified flow was dominant flow pattern in horizontal wet gas pipelines. However, for certain conditions, slug flow along with big wave forms was observed in 2 degree upward flow. The pressure gradient for 2 degree upward flow was higher than horizontal flow since the height of the liquid film was higher in case of upward flow. The pressure gradient decreased significantly as drag reducing agent was added in the pipeline. For slug flow in + 2 degree inclination, the pressure gradient reduction of 19 % was achieved for superficial liquid and gas velocities of 0.03 and 2 m/s at a flow improver concentration of 50 ppm. This was because the flow characteristics such as slug frequency and wave activity were changed with the addition of DRA.

Flow Characteristics of Adiabatic Gas-Liquid Two-Phase Flow in a Horizontal Flat Rectangular Microchannel

2011 ◽  
Author(s):  
Hideo Ide ◽  
Kentaro Satonaka ◽  
Tohru Fukano
Keyword(s):  
Void Fraction ◽  
Slug Flow ◽  
Annular Flow ◽  
Two Phase Flow ◽  
Flow Characteristics ◽  
Flow Patterns ◽  
Phase Flow ◽  
Similar Data ◽  
Two Phase ◽  
The Mean

Experiments were performed to obtain, analyze and clarify the mean void fraction, the mean liquid holdup, and the liquid slug velocity and the air-water two-phase flow patterns in horizontal rectangular microchannels, with the dimensions equal to 1.0 mm width × 0.1 mm depth, and 1.0 mm width × 0.2 mm depth, respectively. The flow patterns such as bubble flow, slug flow and annular flow were observed. The microchannel data showed similar data patterns compared to those in minichannels with the width of 1∼10mm and the depth of 1mm which we had previously reported on. However, in a 1.0 × 0.1 mm microchannel, the mean holdup and the base film thickness in annular flow showed larger values because the effects of liquid viscosity and surface tension on the holdup and void fraction dominate. The remarkable flow characteristics of rivulet flow and the flow with a partial dry out of the channel inner wall were observed in slug flow and annular flow patterns in the microchannel of 0.1 mm depth.

Two-Phase Upward Flow in a Slightly Deviated Pipe

2014 ◽  
Vol 136 (5) ◽  
Author(s):  
Abolore Abdulahi ◽  
Barry J. Azzopardi
Keyword(s):  
Void Fraction ◽  
Silicone Oil ◽  
Flow Characteristics ◽  
Flow Patterns ◽  
Visual Observation ◽  
Wire Mesh ◽  
Vertical Position ◽  
Upward Flow ◽  
Two Phase ◽  
Observation Methods

This study was undertaken to look at the effect of a slight inclination of pipe on upward flow characteristics especially at 10 deg from vertical position. Air-silicone oil flows in a 67 mm diameter pipe have been investigated using a capacitance wire mesh sensor (WMS) and electrical capacitance tomography (ECT). They provide time and cross-sectionally resolved data on void fraction. Superficial gas and liquid velocities of 0.05–1.9 and 0.05–0.5 were studied. Statistical methods and visual observation methods were used to characterize the fluid flows obtained into different flow patterns. From the output results from the tomography instruments, flow patterns were identified using both the reconstructed images as well as the characteristic signatures of Probability density function (PDF) plots of the time series of cross-sectionally averaged void fraction. Bubbly, cap bubble, slug, and churn flows were observed when the pipe was deviated by 10 deg from vertical pipe for the range of superficial gas velocities considered.

A Fully Developed Two-Phase Flow Model in Vertical Channels for Bubbly and Slug Flow Regimes

2000 ◽  
Author(s):  
Samir Moujaes ◽  
Erika Sleight
Keyword(s):  
Slug Flow ◽  
Flow Model ◽  
Channel Model ◽  
Rectangular Channel ◽  
Flow Characteristics ◽  
Phase Flow ◽  
Upward Flow ◽  
Circular Channel ◽  
Two Phase ◽  
Comparison Of The Results

Abstract A theoretical model for steady state two-phase vertical upward flow in cylindrical channels is presented. A comparison of the results of this model for a circular channel as well as a reformulated rectangular channel model is partially made with experimental data in the literature. It shows that in general the model predicts the flow characteristics somewhat better in the bubbly regime than the slug flow indicating the need to look further into some of the constitutive relationships used to close the model in this regime.

Pressure Effects on Low-Liquid-Loading Oil/Gas Flow in Slightly Upward Inclined Pipes: Flow Pattern, Pressure Gradient, and Liquid Holdup

SPE Journal ◽  
2019 ◽  
Vol 24 (05) ◽  
pp. 2221-2238 ◽  
Author(s):  
Hendy T. Rodrigues ◽  
Eduardo Pereyra ◽  
Cem Sarica
Keyword(s):  
Pressure Gradient ◽  
Flow Pattern ◽  
Slug Flow ◽  
Annular Flow ◽  
Flow Patterns ◽  
Pressure Effects ◽  
Liquid Holdup ◽  
Liquid Loading ◽  
Interfacial Roughness ◽  
Oil Gas

Summary This paper studied the effects of system pressure on oil/gas low–liquid–loading flow in a slightly upward inclined pipe configuration using new experimental data acquired in a high–pressure flow loop. Flow rates are representative of the flow in wet–gas transport pipelines. Results for flow pattern observations, pressure gradient, liquid holdup, and interfacial–roughness measurements were calculated and compared to available predictive models. The experiments were carried out at three system pressures (1.48, 2.17, and 2.86 MPa) in a 0.155–m–inside diameter (ID) pipe inclined at 2° from the horizontal. Isopar™ L oil and nitrogen gas were the working fluids. Liquid superficial velocities ranged from 0.01 to 0.05 m/s, while gas superficial velocities ranged from 1.5 to 16 m/s. Measurements included pressure gradient and liquid holdup. Flow visualization and wire–mesh–sensor (WMS) data were used to identify the flow patterns. Interfacial roughness was obtained from the WMS data. Three flow patterns were observed: pseudo-slug, stratified, and annular. Pseudo-slug is characterized as an intermittent flow where the liquid does not occupy the whole pipe cross section as does a traditional slug flow. In the annular flow pattern, the bulk of the liquid was observed to flow at the pipe bottom in a stratified configuration; however, a thin liquid film covered the whole pipe circumference. In both stratified and annular flow patterns, the interface between the gas core and the bottom liquid film presented a flat shape. The superficial gas Froude number, FrSg, was found to be an important dimensionless parameter to scale the pressure effects on the measured parameters. In the pseudo-slug flow pattern, the flow is gravity–dominated. Pressure gradient is a function of FrSg and liquid superficial velocity, vSL. Liquid holdup is independent of vSL and a function of FrSg. In the stratified and annular flow patterns, the flow is friction–dominated. Both pressure gradient and liquid holdup are functions of FrSg and vSL. Interfacial–roughness measurements showed a small variation in the stratified and annular flow patterns. Model comparison produced mixed results, depending on the specific flow conditions. A relation between the measured interfacial roughness and the interfacial friction factor was proposed, and the results agreed with the existing measurements.

Comparison of the Performance of Commercial Flow Improvers in Wet Gas Horizontal Pipelines

2004 ◽  
Author(s):  
Cheolho Kang ◽  
Parimal P. More ◽  
William Paul Jepson
Keyword(s):  
Pressure Gradient ◽  
Liquid Film ◽  
Liquid Velocity ◽  
Flow Loop ◽  
Gas Phases ◽  
Wet Gas ◽  
Wide Range ◽  
Superficial Gas Velocity ◽  
Flow Improver ◽  
Commercial Oil

There is a conspicuous absence of flow improver work for wet gas pipeline environments. The tests were carried out in a 44 m long, 10.16 cm diameter, industrial scale multiphase flow loop with a wide range of superficial liquid and gas velocities ranging from 0.03 to 0.1 m/s and 4 to 10 m/s, respectively. Oil with a viscosity of 2 cP and carbon dioxide were used as the liquid and gas phases, respectively. Two commercial oil soluble flow improvers (FI-1 and FI-2) were used for the tests. This paper discusses the comparison of the performance of these flow improvers in wet gas pipelines. FI-1 and FI-2 were able to decrease the pressure gradient in most of the cases. At the same superficial liquid velocity, the pressure gradient reduction increased with an increase in the superficial gas velocity. This was due to the increase in turbulence level at the liquid and gas interface. At superficial liquid and gas velocities of 0.1 and 10 m/s, FI-1 showed a maximum effectiveness of 13% with the reduction of pressure gradient from 86 to 75 Pa/m. Whereas, FI-2 achieved the maximum effectiveness of 25% as the pressure gradient decreased to 65 Pa/m at the same conditions. Flow improver-2 showed a better performance than Flow improver-1 at all conditions. The decrease in the height of the liquid film was accompanied with spread of the liquid film around the pipe circumference with the addition of both the flow improvers. The changes in the height of the liquid film were more significant with FI-2 than FI-1. At certain superficial gas velocities, it was seen that a transition in flow pattern occurred from wavy to smooth stratified flow with the addition of both the flow improves. This was because the flow was much smoother at the gas-liquid interface with flow improvers.

The Use of Flow Improvers to Decrease Pressure Drop in Multiphase Pipelines

2002 ◽  
Author(s):  
C. Kang ◽  
W. P. Jepson
Keyword(s):  
Carbon Dioxide ◽  
Pressure Drop ◽  
Flow Pattern ◽  
Slug Flow ◽  
Large Decrease ◽  
Upward Flow ◽  
Flow Loop ◽  
Downward Flow ◽  
Water Cut ◽  
Flow Improver

Experiments were performed in a 10-cm diameter, 44 m long Plexiglas pipes, multiphase flow loop to examine the effect of flow improver in slug flow at inclinations of ±5degrees. Superficial liquid velocities between 0.5 and 1.5 m/s and superficial gas velocities between 2 and 6 m/s were studied. A 2.5 cP oil at 25 °C was used and water cut was 10%. The experiments were undertaken at a pressure of 0.13 MPa and a temperature of 25 °C with carbon dioxide as the gas. The effectiveness of flow improver on pressure drop and slug frequency was examined for concentrations ranging from 0 ppm to 50 ppm. The results showed that the flow improver was effective in reducing the pressure drop significantly at all superficial liquid and gas velocities. The flow improver concentration of 50 ppm was more effective than 25 ppm for all cases. At superficial gas velocities of less than 4 m/s and all liquid velocities with 50 ppm flow improver, the effectiveness of flow improver in upward flow was around 30%. At superficial liquid and gas velocities of 1.0 and 2 m/s with 50 ppm flow improver concentration, the effectiveness of up to 64% was achieved in downward flow. The slug frequency in both upward and downward flows decreased significantly in all cases with addition of flow improver. For example, at superficial liquid and gas velocities of 1.5 and 2 m/s, the slug frequency in downward flow decreased from 43 to 14 slugs/min. when 50 ppm of chemical was added. The flow pattern in downward flow was changed from slug flow to stratified flow at several velocities, which led to a large decrease in the pressure drop.

scholarly journals Experiment on the Effect of Superficial Gas-Liquid Velocities on Slug Flow-Induced Vibration in an Inclined Sagged Riser

2020 ◽  
Author(s):  
Bowen Ma ◽  
Narakorn Srinil ◽  
Hongjun Zhu ◽  
Yue Gao
Keyword(s):  
Slug Flow ◽  
High Speed ◽  
Liquid Velocity ◽  
Flow Characteristics ◽  
Flow Patterns ◽  
Small Scale ◽  
Flow Induced Vibration ◽  
Pressure Transducers ◽  
Test Loop ◽  
Flow Features

Abstract Subsea liquid-gas flows conveyed through a flexible riser or pipeline may develop into various flow patterns including slug flow. In this study, the slug flow-induced vibration (SIV) of an inclined sagged riser conveying upward air-water flows is experimentally investigated. A small-scale experiment is carried out in an air-water test loop with a section of a free-hanging catenary tube made of silica gel. Attention is placed on the effect of superficial gas and liquid velocities on SIV responses. Both pipe motions and flow patterns are recorded using non-intrusive high-speed cameras. Pressure variations are also measured at the pipe inlet and outlet by two pressure transducers. The SIV system is tested by employing different ratios of the superficial gas-liquid velocities. Occurrence of unstable slug flows is captured at the relatively high gas-to-liquid velocity ratios, leading to a large-amplitude SIV. Experimental results of the space-time varying riser responses and oscillation frequencies are reported together with the associated slug flow features. Depending on the gas-liquid superficial velocities, slug flow characteristics are observed to vary significantly. These entail an intermittent SIV with modulated amplitudes and frequencies along riser span, signalling a potential dynamic stress and fatigue-related concern. In all experimental cases, the riser responses are found to be multi-modal and dominated by the fundamental planar mode whereas an out-of-plane vibration is negligible. Experimental observations suggest the key interrelationships of the two-fluid flow conditions, the slug characteristics and the pipe dynamics. This finding is meaningful for a practical design of riser transporting internal multiphase flows.

Pressure Drop of Accelerating Slug Flow in Microchannels: Modeling and Experiment

2010 ◽  
Author(s):  
Shahnawaz Molla ◽  
Dmitry Eskin ◽  
Farshid Mostowfi
Keyword(s):  
Pressure Drop ◽  
Pressure Gradient ◽  
Flow Velocity ◽  
Gas Phase ◽  
Void Fraction ◽  
Slug Flow ◽  
Gas Bubbles ◽  
Liquid Slug ◽  
Local Pressure ◽  
Wide Range

An investigation on the pressure drop of a gas-liquid slug flow through a long microchannel of rectangular cross-section is presented. A constant pressure gradient in the microchannel was observed in a flow where gas bubbles progressively expanded and the flow velocity increased due to significant pressure drop. In contrast to majority of the earlier studies of slug flow in microchannels, where void fraction was nearly constant throughout the channel, we investigated systems where the volume of the gas phase increased significantly due to large pressure drop (up to 2000 kPa) along the lengthy (∼1 m) channel. This expansion of the gas phase led to a significant increase in the void fraction, causing considerable increase in flow velocity. Local pressure was measured along the channel using a series of embedded membranes acting as pressure sensors. The axial pressure profile for a gas-liquid system, namely, Dodecane/Nitrogen was studied. Our investigation on pressure gradient showed linear trend over a wide range of void fractions (30–90%) and flow conditions in the two-phase flow. The lengths and the velocities of the liquid slugs and the gas bubbles were also studied along the microchannel by employing video imaging technique. Furthermore, a model describing the gas-liquid slug flow in long microchannels was developed. Excellent agreement between the developed model and the experimental data was obtained.

Study on the Flow Characteristics of Shengli Oilfield Super Heavy Oil

2017 ◽  
Vol 10 (1) ◽  
pp. 69-78 ◽  
Author(s):  
Wang Shou-long ◽  
Li Ai-fen ◽  
Peng Rui-gang ◽  
Yu Miao ◽  
Fu Shuai-shi
Keyword(s):  
Pressure Drop ◽  
Pressure Gradient ◽  
Heavy Oil ◽  
Flow Characteristics ◽  
Fluid Viscosity ◽  
Linear Flow ◽  
Start Up ◽  
Non Linear ◽  
Core Permeability ◽  
Velocity Pressure

Objective:The rheological properties of oil severely affect the determination of percolation theory, development program, production technology and oil-gathering and transferring process, especially for super heavy oil reservoirs. This paper illustrated the basic seepage morphology of super heavy oil in micro pores based on its rheological characteristics.Methods:The non-linear flow law and start-up pressure gradient of super heavy oil under irreducible water saturation at different temperatures were performed with different permeable sand packs. Meanwhile, the empirical formulas between start-up pressure gradient, the parameters describing the velocity-pressure drop curve and the ratio of gas permeability of a core to fluid viscosity were established.Results:The results demonstrate that temperature and core permeability have significant effect on the non-linear flow characteristics of super heavy oil. The relationship between start-up pressure gradient of oil, the parameters representing the velocity-pressure drop curve and the ratio of core permeability to fluid viscosity could be described as a power function.Conclusion:Above all, the quantitative description of the seepage law of super heavy oil reservoir was proposed in this paper, and finally the empirical diagram for determining the minimum and maximum start-up pressure of heavy oil with different viscosity in different permeable formations was obtained.

Pressure-Flow Characteristics During Peristaltic Transport of Non-Newtonian Fluid in Distensible Tube With Different Wave Forms

2003 ◽  
Author(s):  
Prasanna Hariharan ◽  
Rupak K. Banerjee
Keyword(s):  
Newtonian Fluid ◽  
Flow Rate ◽  
Flow Characteristics ◽  
Pressure Flow ◽  
Square Wave ◽  
Wall Movement ◽  
Power Law Fluids ◽  
Significant Difference ◽  
Wave Forms ◽  
Distensible Tube

This study analyzes the pressure-flow characteristics during the peristaltic pumping of power law fluids in an axi-symmetric non-uniform distensible tube. The analyzed geometry is of a diverging shape that is common in several biological flow conduits, especially in mammals. Using the Fourier series, the dimensionless wall coordinates for sinusoidal, triangular, trapezoidal, and square wave forms are obtained to simulate wall movement. Equations expressing the pressure-flow rate relationship for different wall shapes are developed from the wave equation. Pressure-flow and velocity plots are obtained by solving the equations numerically. The results indicate that there is significant difference in pressure-flow relationship between Newtonian and non-Newtonian fluid. Also, the maximum flow rate can be achieved when the wall movement follows a square wave form.

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