Characterisation of the mean and time dependent properties of inclined oil-in-

water pipe flows using dual-sensor probes

G. Lucas and Xin Zhao University of Huddersfield, UK

• In the oil industry, horizontal and inclined oil-in-water flows are frequently encountered.

• Dual-sensor conductance probes and arrays of probes are presented for measuring the time averaged and the time dependent local properties of such flows including the oil droplet axial velocity and the local oil volume fraction.

• The experimental results from the dual sensor arrays have been used for comparison with, and validation of, numerical models of inclined oil-in-water flow.

• The probe arrays enable time dependent intermittent structures, such as Kelvin-Helholtz waves, to be observed.

Video1. Qw =3.5m3/h ;Qo= 1.0m3/h; incline angle = 30°(from the vertical)

Click here to view the animation

2 , 1 , 2 , 1 ,1 1

1 1( ) ( )

=2

N N

f i f i r i r ii i

t t t tT T

0

1

GlueStainless

steel tube 5mm diameter

Wires

PTFE coated steelneedle of 0.15 mm

outer diameter

0.3mm

0.5mm

Ceramic guideof 2mmdiameter

1.5mm

1 ft 1rt 2 ft 2rt Time

Con

duct

ance

1, 1 , 1 ,i r i f it t t

2, 2 , 2 ,i r i f it t t

1, 2,1

2 1

( )

N

oi ii

su

N t t

Dual-sensor probe design and mathematical model

Local oil volume fraction from N bubbles

Local oil velocity from N bubbles

To obtain accurate estimates of the oil velocity and the oil volume fraction it is necessary to sample a minimum number N of bubbles.

In the present study, for ‘Time averaged’ data, this was achieved using a ‘Time Window’ or ‘Sampling Interval of 60 seconds’

For ‘Time Dependent’ data a ‘Sampling Interval’ of 0.05 seconds was used

Time averaged local oil volume fraction and velocity distributions obtained in inclined oil-in water flow in an 80mm diameter pipe

80mm inclined oil-water test loop

80mm internal diameter, 2.5m long test section.

A traverse mechanism was used to move an individual dual-sensor probe to each of 61 spatial locations in the flow cross section.

A 60 second sampling interval was used to obtain time averaged local oil volume and local oil velocity measurements.

The local volume fraction and the local axial velocity profile distribution of 30 degree inclined pipe (80mm,Qw=3.5m3/h,Qoil=1.0m3/h)

Measuring time averaged values of the local oil volume fraction and the local axial oil velocity using a traverse mechanism

Locations of the four dual-sensor probes in the 80mm diameter pipe

12

3410mm

10mm

20mm20mm

20mm

Wi re outl et

I ncl i nedangl e f romverti cal

Upper side ofinclined pipe

lower side ofinclined pipe

Probe holder

Brass bar

To measure the time dependent flow properties at different locations on a diameter of an 80mm pipe an array of four dual-sensor probes is used.

The local oil volume fraction and the local oil velocity is measured at each probe averaged over a ‘sampling interval’ or ‘time window’ of 0.05 seconds.

t

y

16 pixels

probe1

probe2

probe3

probe4

4 pi

xels

1a

2a

3a

4a

1b

2b

3b

4b

1c

2c

3c

4c

Volume fraction data from the dual-sensor array can be plotted using a gridwhere y represents probe position in pipe and t represents time (in time stepsT of 0.05 seconds). 16 time steps are displayed in each frame.

By introducing the mean axial oil velocity uo in the cross section, the time axis canbe converted to a distance d where d=16× uo×T.

In the following slide, uo=0.4m/s and so the axial pipe length shown is 320mm.

100Flow direction

Volume fraction and after interpolated volume fraction

Black-white pixel volume fraction and the interpolated data (inclination angle =30 degrees )

/h1.0m Qo/h,3.5mQw 33

In inclined oil water flows there is a large velocity gradient, with the oil droplets travelling much faster at the upper side of the inclined pipe than at the lower side.

By introducing the mean axial oil velocity uo,p measured at the position of the pth probe the pixel length lp can be adjusted to represent the distance travelled by the oil droplets in the sampling interval T (where T=0.05 seconds) as follows:

lp=T uo,p

This method of data representation can help to reveal time dependent flow properties such as the ‘breaking’ of Kelvin-Helmholtz wave structures in the flow.

Frame =112

Frame =111

Frame =110

Frame =109

Successive frames of local oil volume fraction data separated by 0.05s. Pixel length is dependent upon local axial oil velocity at the given probe.

34.5m /wQ h

31.5m /oQ h

o45 o45

31.5m /oQ h

o45

An array of 11 dual-sensor probes was used to investigate the mean and time dependent properties of inclined oil-in-water flows in a 150mm diameter 15m

long flow loop at Schlumberger Cambridge Research

Array of 11 dual-sensor probes Array mounted in 150mm diameter flow loop

y

t

30 pixelsprobe1probe2probe3

probe10

11 p

ixel

s

…...

probe11

1a2a3a4a5a6a7a8a9a10a11a

1b2b3b4b5b6b7b8b9b

10b11b

1c2c3c4c5c6c7c8c9c10c11c

Local oil volume fraction versus time

Each row represents data taken at a given probe location

Each column represents a time interval of 0.05 seconds

Local oil volume fraction vs time (sampling interval =0.05s)

(Qw=16.4m3/hr; Qo = 6 m3/hr; inclination angle = 45°)

Click here to view the animation

Local oil volume fraction and local oil axial velocity vs time

(sampling interval =0.05s)

(Qw=16.4m3/hr; Qo = 6 m3/hr; inclination angle = 45°)

Click here to view the animation

Interpolated local oil volume fraction and local axial oil velocity vs time (sampling interval = 0.05s)

(Qw=16.4m3/hr; Qo = 6 m3/hr; inclination angle = 45°)

Click here to view the animation

Mean oil volume fraction versus probe position (Qw=16.4, Qo=6, theta=45 degrees)

Oil Volume Fraction versus distance from upper side of pipe (Qw=16.4 cubic metres/hr, Qo=6 cubic metres/hr, inclination=45 degrees)

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150

Probe distance from upper side of inclined pipe (mm)

Oil

volu

me

fra

ctio

n

Upper side of inclined pipe

Lower side of inclined pipe

Mean oil axial velocity versus probe position (Qw=16.4, Qo=6, theta=45 degrees)

Oil axial velocity versus distance from upper side of pipe(Qw=16.4 cubic metres/hr, Qo=6 cubic metres/hr, inclination =45 degrees)

00.10.20.30.40.50.60.70.80.9

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150

Probe distance from upper side of inclined pipe (mm)

Oil

axia

l vel

ocity

(m

/s)

Upper side of inclined pipe

Lower side of inclined pipe

Characterisation of time dependent flows by investigating standard deviation of flow phenomena over different time

windows

Standard deviation of oil volume fraction fluctuations versus k for top 8 probes (Qw=16.4, Qo=6, theta=45 degrees)

Standard deviation of oil volume fraction fluctuations versus k for top 8 probes (p1 is top probe; p8 is eighth probe)

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0 1 2 3 4 5 6 7 8 9

Parameter k

Sta

ndra

d de

viat

ion

of v

olum

e fr

actio

n flu

ctua

tions

p1

p2

p3

p4

p5

p6

p7

p8

‘Time window’0.05 seconds

‘Time window’0.8 seconds

‘Time window’ 25.6 seconds

Standard deviation of oil axial velocity fluctuations versus k for top 8 probes (Qw=16.4, Qo=6, theta=45 degrees)

Standard deviation of oil axial velocity fluctuations versus parameter k for top 8 probes (p1 is top probe; p8 is eighth probe)

0

0.05

0.1

0.15

0.2

0.25

0.3

0 1 2 3 4 5 6 7 8 9

Parameter k

Sta

ndar

d de

viat

ion

of o

il ax

ial v

eloc

ity (

m/s

)

p1

p2

p3

p5

p6

p7

p8

‘Time window’ 0.05 seconds

‘Time window’0.8 seconds

‘Time window’25.6 seconds

Nottingham model of inclined oil-water flow

(Qw=16.4m3/hr; Qo = 6 m3/hr; inclination angle = 45°)

Click here to view the animation

Local oil volume fraction and oil axial velocity vs time from Nottingham model using a sampling interval of 0.05s(Qw=16.4m3/hr; Qo = 6 m3/hr; inclination angle = 45°)

Data taken from numerical model at a distance of 0.9L from inlet where L is the modelled pipe length - and at positions corresponding to the 11 probes used in the equivalent experiment at the same flow

conditions.

Click here to view the animation

Mean oil volume fraction versus probe position

(Qw=16.4, Qo=6, inclination=45 degrees)

Comparison of experimental data with results from Nottingham model

Mean oil volume fraction versus distance from upper side of inclined pipe (comparison of experimental data and data from numerical model)

00.050.1

0.150.2

0.250.3

0.350.4

0 50 100 150

Distance from upper side of inclined pipe (mm)

Mea

n oi

l vol

ume

frac

tion

Probes (exptl data)

Numerical model

Standard deviation of oil volume fraction fluctuations versus k from Nottingham model

(at positions corresponding to top 8 probes used in experiments)

Qw=16.4, Qo=6, inclination=45 degrees

‘Time window’0.05 seconds

‘Time window’0.8 seconds

‘Time window’ 25.6 seconds

Standard deviation of oil volume fraction fluctuations versus k from numerical model

0

0.02

0.04

0.06

0.08

0.1

0.12

0 1 2 3 4 5 6 7 8 9

Parameter k

Sta

ndar

d de

viat

ion

of

volu

me

frac

tion

fluct

uatio

ns

p1

p2

p3

p4

p5

p6

p7

p8

ITS Z8000 ERT system (ITS)

EIT system experiments

An ITS Z8000 dual-plane ERT system was used to measure the Kelvin-Helmholtz (K-H) wave speed in vertical and inclined oil-in-water flows in a pipe of diameter 80mm.

The K-H wave speed was obtained by cross correlating conductance data obtained from the two planes at 450 frames per second per plane.

For each inclination angle,10 different flow conditions were investigated for which the homogeneous velocity was in the range 0.11m/s to 0.49 m/s and the mean oil volume fraction was in the range 0.04 to 0.26.

0. 1

0. 2

0. 3

0. 4

0. 5

0. 6

0 0. 2 0. 4 0. 6u h

u

15 degree

30 degree

45 degree

60 degree

K-H wave speed versus homogeneous velocity in an 80mm diameter pipe

Initial results suggest that the K-H wave speed may provide a method for measuring the homogeneous velocity (mixture superficial velocity) in inclined oil-water flows.