Characterisation of the mean and time dependent properties of inclined oil-in- water pipe flows...
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Transcript of Characterisation of the mean and time dependent properties of inclined oil-in- water pipe flows...
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.