MEK 4450 – Multiphase pipeline transport (IFE)

Lecture notes 2012-10-29, Morten Langsholt, morten@ife.no

• 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

3

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

7

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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