Multiphase Pipeline Transport - Forsiden · MEK 4450 Multiphase Flow - IFE Oct. 29, ... PIV @ IFE:...
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MEK 4450 – Multiphase pipeline transport (IFE)
Lecture notes 2012-10-29, Morten Langsholt, [email protected]
• Lab excercise • Instrumentation
• PIV • X-Ray tomography
• Lab-demo
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Excercise
1. Open the Excel-file and get familiar with how to use it 2. Use data from the lab test and ‘plug’ the data into the model. Compare
the predicted holdup and pressure drop values with the measured data for the different test conditions. Discuss the results.
3. For pipe inclination 3 deg. and Usl=0.5 m/s, calculate and plot the pressure drop as a function of the gas velocity. Explain the results.
4. Describe what occurs for pipe inclination 4 deg, Usl=0.001 m/s and Usg= 3.5 m/s.
β
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Measurement data from lab exercise MEK 4450, IFE 22. Oct.
T e st co nd itio ns Fluid p ro p e rtie sPressure 4 bara Density Dyn. vis Kin.vis
Pipe dia. 0.099 [m] [kg/m3] [Pa s] [m2/s]
Pipe area 0.0077 [m2] Oil 815 0.002 2.44E-06
Pipe rough 0.00025 [-] Gas 24 0.000015 3.01E-07
Exp no Incl. Usgas Usoil dp/dz Holdup Flow regim# θ [m/s] [m/s] [Pa/m] [-]
MEK 4450 Multiphase Flow - IFE Oct. 29, 2012
Input parameters Obser- Measurements Model
vation Exp. no Pipe incl. Usg Usoil Flow H dp/dz H dp/dz [deg.] [m/s] [m/s] regime [-] [Pa/m] [-] [Pa/m]
1 -0.4 1.27 0.24 Stratified smooth 0.36 6 0.29 16 2 -0.4 4.64 0.22 Stratified ripple 0.17 94 0.14 119 3 0 1.59 0.29 Stratified large waves 0.41 34 0.34 41 4 0 3.13 0.28 Stratified wavy 0.27 74 0.22 84 5 0 5.00 0.29 Stratified w/disp. 0.20 134 0.16 157 6 0 6.84 0.27 Stratified w/disp. 0.15 213 0.13 235 7 0 8.62 0.26 Stratified w/disp. 0.11 323 0.10 324 8 1 0.42 0.38 Elongated bubble 0.69 125 0.78 131 9 3 0.77 0.06 Slug flow 0.48 200 0.72 319
10 3 3.22 0.12 Large waves 0.22 128 0.24 151
11 3 6.71 0.11 Stratified w/dispersions 0.09 185 0.08 194
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Task 2 – Calculate H and dp/z Discuss results
1. F 2. D
β
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Task 3 – For pipe inclination 3 deg. and Usl=0.5 m/s, calculate and plot the pressure drop as a function of the gas velocity. Explain the results.
1. F 2. D
β
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Task 4 – Describe what occurs for pipe inclination 4 deg, Usl=0.0001 m/s and Usg= 2.8 m/s.
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Examples advanced instrumentation
MEK 4450 Multiphase Flow - IFE Oct. 29, 2012
• Digital Particle Image Velocimetry – DPIV for whole field velocity and turbulence measurements
by Gustavo Zarruk
• X-Ray tomography system for phase distribution and interface structure mapping
by Bin Hu
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At IFE we have DPIV and Time-Resolved DPIV What is it? • Non-intrusive measurement
technique • Excellent temporal and spatial
resolution • High repetition laser • High speed camera • Digital image processing • Fancy mathematics and statistics
Frame rate vs Resolution Typical 5400 @ 1024x1024 pixels Maximum 675,000 @ 64x16 pixels
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Time Resolved Particle Image Velocimetry (TRPIV)
Fundamentals of Digital Particle Image Velocimetry - Westerweel (1997)
• Fluid Velocity inferred from ideal tracer particles • Velocity measured indirectly from particle displacement • Tracer particles are described in terms of a pattern • 2D – TRPIV
• Cross section of the flow is illuminated with a thin light sheet (Dual pulsed laser)
• Tracer particles in the light sheet are projected onto a recording medium ~ CCD or CMOS high speed camera - TRPIV
• Image pair acquired in a short period of time dt~Ο (1µs) • FFT-based cross-correlation performed on small interrogation
windows • Correlation peak ~ particle pattern displacement, ds
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PIV Schematic
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How does it look?
Bad PIV but good for explaining
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PIV Velocity Estimation
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Partickle Tracking A hybrid digital particle tracking velocimetry technique – Cowen & Monismith (1997)
DPIV results
Particle Tracking Algorithm
I1(t) I2(t+dt)
New particle Tracked particle
Out of field of view
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Results sample Fluid Velocity and Vorticity
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PIV @ IFE: Particle flow in pipelines Raw Images Fluid Velocity
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Final result
Poelma et. al. (2006)
Fluid and Particle Velocity Information
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PIV and PTV in Slug Flow
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Evolution of liquid phase velocity in slug zone
8 7 6 5 1 3 4 2 9 10 11
5
3 2
7 6
1
8
4
9 10
11
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Costs Operational • Measurement time
Depends on: • Camera characteristics • Frames per second • Image resolution • Inboard camera memory
• Examples: 4GB memory with 1000 fps @ 1024 x1024 pixels = 3 s 4GB memory with 3000 fps @ 512 x 512 pixels = 4 s 4GB memory with 250 fps @ 256 x 256 pixels = 192 s
• Data processing • 24 hours with an optimal processing algorithm • Days – months for large data sets
Financial • State of the art system 2-3 MNOK • Startup system MNOK 0.6
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A fast X-ray tomography system in multiphase pipe flow measurement Over years, large amount of work carried out to design
systems to measure the complex multiphase flows Traditional methods
• Conductivity/impedance probe • Wire-mesh probe • Quick closing valve
State-of-art methods developed recently (non-intrusive) • Neutron radiography • Gamma densitometer • X-ray tomography
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Principle and setup of IFE’s X-ray system
Source 2
Source 1
X-ray camera 1
X-ra
y ca
mer
a 2
Sampling rate
Max. 300 Hz
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X-ray system on the Well Flow Loop
200kg
60cm
10cm Test section
Sleeve
Collimator
Camera
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What can it measure?
Side view liquid gas
Top view
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Typical results from X-ray CT system 1. Projection views (side and top) 2. Mean holdup traces (cross-sectional averaged) 3. Tomographs 4. 3D view of the flow 5. Slice view 6. Y-axis phase distribution 7. Interface structure 8. Evolution of phase transport along slug or wave 9. Many more … (wave/slug length, frequency and amplitude etc.)
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Comparison of time-history plots USL=0.5 m/s and USG = 2.5~7.9 m/s
2.5
3.5
4.6
5.7
6.7
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R1: Projection view
Side view
Top view
USG = 1.18 m/s, USL = 1.0 m/s, P = 7.2 bara, +5 deg inclination, 120 Hz sampling rate
Note: colours given by local holdup
Flow
liquid gas
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R2: Mean holdup traces
Liquid holdup
Flow
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R3: Tomograph - reconstruction algorithm
A . =
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R4: 3D view of the flow
~14D
VT
Breaking slug front
Gas penetration
Side view
Top view
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R6: Vertical phase distribution (Y-axis)
Void fraction
Void fraction
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R7: Interface structure
Flow
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R9: Wave height, frequency etc.
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3-phase slug flows
Side view
Top view Flow
Green = gas, red = oil, blue = water
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Conclusion • Mean holdup and distribution of phases
• Cross-sectional • Time series
• Mixing effects and entrained volume fraction • Cross-sectional • Time and space distribution
• Interface structures • interface roughness, large waves
• Statistical values for wave and slug flows • Wave height • Frequency • Slug body length and distribution
• Applied to two- and three-phase flows
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Lab-demo I Water accumulation in gas-condensate pipelines
• Water accumulation: When the water fraction in the holdup (Hw/Htot) is larger than the water cut at the inlet (Us,water/Us,total)
• Occurs when oil and water are separated – it is then possible with large velocity differences (slip) between the liquids.
• Degree of water accumulation determined by flow rates, pipe inclination and fluid properties.
• For the fluids in the Well Flow Loop we get significant water accumulation for pipe incl. 1o, Usg=1.5 m/s, Uso=0.1 m/s and Usw=0.001 m/s.
• The inlet WC is then 0.1% - but the water cut in holdup is close to 40% - AS WILL BE SEEN IN THE LAB
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• Test 1 – Gas-condesate flow with varying Usg: Uphill 2o, Uso=0.04,
Usw=0.001 m/s, Usg=4.0 –> 2.0 m/s • Usg=4 m/s: Entrained drops, film on wall , holdup ~4%, no oil-water slip • Usg=3 m/s: Reduced drop field, holdup increases to ~10%, • Usg=2 m/s: No drop entrainment, stagnant wall film, liquid transport in
waves/slugs, holdup ~18%, water accumulation • Test 2 –Start-up with liquid in low point : Uphill 3o, starts with Usg=1
m/s, increasing to 2 m/s and then 3 m/s • Test 3 – Hydraulic jump: Uphill 5o, liquid initially in low point, Usg=2.5
m/s • If lucky, we see an hydraulic jump.
Lab-demo II Multiphase flow at gas-condensate conditions
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