seminar-2 dec 2011 experimental investigation
TRANSCRIPT
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Mechanical & Industrial Engineering DepartmentSultan Qaboos University
College of Engineering
M.Sc. Seminar II
Evaluation of Swelling-Elastomer Seals in PetroleumApplications : Experimental Investigation
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2
Problem Statement and Objective4
Background2
Swellable Packers3
Experimental work5
Conclusions6
Motivation and Significance1
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Swellable elastomers have many applications toimprove performance of oil and gas wells.
Real-world applications, especially in Oman (oiland gas are the main source ofcountrys income)
Significant cost savings compared to theconventional methods used in well applications
Analytical approach can predict elastomerperformance for various actual field conditions.
Experimental evaluation can be very costly, and isnot even possible in many cases.
Numerical simulations, if validated, can be moreconvenient; but still have to be run for eachcondition
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Solid Expandable Tubular (SET)
SET Technology is a down-hole process consisting
of expanding the diameter of a tubular by pushing
or pulling a cone through it while preserving itsintegrity. The tubular deforms beyond its elastic
limit into the plastic region but remains below its
ultimate tensile strength. Sealing elements in SET
applications are generally swelling elastomers.
A new approach in well-bore DESIGN & REMEDIATION 4
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Cementing
External Casing Packers (ECPs)
Chemical Shutoff
Swellable Packer
Used when primary cement jobs are
difficult, or in critical areas of wellconstruction to ensure long term wellintegrity.
Saves time
Provides zonal insulation instead of
cementing Reduces the size of well hole
The swelling time can be engineered tomeet the well requirements.
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A rubber-like material that swellswhen immersed in fluids (water,hydrocarbon, or mixture of both)
Liquid enters elastomer throughosmosis or diffusion mechanism
Volume increases proportionally asliquid diffuses into elastomer
Swelling process continues until aswell limit is reached (spatial
confinement or internal rubber stress)
Swell time and volume can becontrolled
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Swell packers are important in
Improving existing wells,
Aiding oil recovery from difficult or
abandoned fields; etc
Failure of swell packers can lead to significant
losses in terms of time and money. Sealing failure (leakage) can occur if
Swelled thickness is not enough to fill the
gap between the tubular and the
casing/formation.
Differential pressure (po) of well is more
than sealing pressure
Well conditions are beyond the elastomer
limit (eg. high temp).
9
(a)
Elastomer
Tubular
Smoothsurfacegeometry
Casing/formation
(b)
Elastomer
Tubular
Casing/formation
Smoothsurfacegeometry
Fluid
PO
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The main aim of the project is
Performance evaluation of swelling elastomer sealsused in oil well applications under different fieldconditions.
The work includes
Designing, conducting, and analyzing a series ofexperiments for determination of swelling behaviorand mechanical properties of elastomer (before andafter swelling)
Describing the behavior of elastomer seals analytically
by deriving a closed form model for sealing pressuredistribution along axial direction of elastomer seal
Numerical modeling and simulation of elastomer sealusing FEM packages such as ABAQUS, using most
appropriate material model of rubber-like materials 10
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Performance of Elastomer Seals
Experimental work
Analytical model
Numerical (finite element) model
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12(a)
Ela
stomer
T
ubular
Smoothsurfacegeometry
Casing/formation
(b)
E
lastomer
Tu
bular
Casing/formation
Smoothsurfacegeometry
Fluid
PO
Model sealing pressure distribution along elastomerseal as a function of
- Seal geometry - Compression ratio - Material properties
- Well conditions (pressure, friction, etc.)
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coshcosh13
12
1
11
1
2
1
1
Zh
p
v
v
tv
EZ
o
R
13
Casing/formation
Fluid
1
Po
R2h
R2
R2 - R1 t
Z
dZ
Z
4
2
14
122
1 ~
2and
~ tvR
ER
KvtR
ERRt
ss
1
2
12
2
)( ZpdZ
pd
p
v
v
v
ERR
1
3
1
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Elastomer
Test
SwellingTests
- Hardness
- Volume
- Thickness
- Density
MechanicalTests
Compressiontest (E)
Bulk test (K)
14
Shear modulus G
Poissons ratio v
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Hardnessmeasurement
(Durometer)
Thicknessmeasurement
(Verniercalipers)
Volumemeasurement
(graduatedcylinder)
Densitymeasurement
(Digital Balance)
Elastomers
Water-base
35000 ppm
85000 ppm
Oil-base Crude oil
No standard method forSwelling test
The readings were taken beforeswelling and after 1, 3, 7, 15, and
30 days of swelling
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If calculated v is 0.495
If the errors in measurement G is 10% K20 %
Errors in calculated v 0.5%
If calculated v is 0.495 If the errors in measurement
Eis 10% K20 %
Errors in calculated v 0.3%
If calculated v is 0.495 If the errors in measurement
Eis 10% G20 %
Errors in calculated v 90%
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K
K
vE
E
vv
2
11
2
11
G
G
v
v
E
E
v
v
v
11
GK
GK
26
23
GG
vE
E
v
G
G
v
vv
K
K
v
vv
v
3
121
3
121
v is highly sensitive to stressdistribution (Yu et al., 2001).
No standard method for directmeasurement ofv
Can be measured indirectly
using equations 0.495
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Tensile test ISO-37 ASTM D412
Universal testing machine; tensionmode
Compression test ISO-7713 More relevant to elastomer seal
applications EC>>ET Universal testing machine;
compression mode
Youngs Modulus E
E
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No standard method to measure K;
All techniques require
A pressurization chamber,
A means to raise and lower pressure, and
A method to measure volume change.
Pressure system may be mechanical or hydraulic
v
pK
pA
Fp
o
vV
V
Bulk Modulus K
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v
pK
pA
Fp
o
o
o
ov
t
tt
v
vv
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Sample configuration: disc (ASTM-D575)
Test temperature: 50oC
Transparent sealable jars Salt concentration of brine
0.6% (low salinity), and 12 % (high salinity).
Testing time: 30 days
Readings before swelling and after 1, 2, 4, 7, 16, 23
and 30 days of swelling.
Tinius Olsen universal testing machine
(compression mode)
28.5 0.5 mm
12.5 0.5 mm
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After comparison, Fishman and Machmer (1994) conclude that Peng
method is best Fixture was designed in such a way that under compressive loading
specimen is constrained to move only in longitudinal direction andtotally restricted in radial direction
0
10000
20000
30000
40000
50000
0 0.5 1 1.5 2
Force(N)
Compression (mm)
bulk experiment _ 1 day swelling elastomer (12% & 50 oC)
sample 1 sample 2 sample 3
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HardnessChange
DensityChange
0
10
20
30
40
50
60
70
80
0 10 20 30 40
Hardness
Time (Days)
Plates in 85000 ppm water
0
5
10
15
20
25
30
0 10 20 30 40
DensityChange(%
)
Days
Plates in 85000 ppm water
Material A Material B
0
10
20
30
40
5060
70
0 10 20 30 40
DensityChange(%
)
Days
Discs in 85000 ppm water
Material A Material B
0
20
40
60
80
0 10 20 30 40
Hardness
Days
Discs in 35000 ppm water
Material A Materail B
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ThicknessChange
VolumeChange
0
5
10
15
20
25
0 10 20 30 40
Thickness(%)
Days
Plates in oil
0
10
20
30
40
50
60
0 10 20 30 40
Thickness(%)
Days
Plates in 35000 ppm water
0
20
40
60
80
100
120
140
0 10 20 30 40
VolumeChange(%)
Days
Plates in 35000 ppm water
0
10
20
30
40
50
60
70
0 10 20 30 40
VolumeChange(%
)
Days
Plates in oil
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-2.5
-2
-1.5
-1
-0.5
0
-0.8 -0.6 -0.4 -0.2 0
eng
(MPa)
eng
Stress strain curve (day 4 , 12 %, 50 oC)
Sample 1 Sample 2 Sample 3
y = 1.4059x - 0.0742
R = 0.9993
y = 1.3029x - 0.0692
R = 0.9973
y = 1.2493x - 0.0236R = 0.9952
-0.25
-0.2
-0.15
-0.1
-0.05
0
-0.15 -0.1 -0.05 0
eng
(MPa)
eng
Stress strain curve (day 4 , 12 %, 50 oC)
25
-1.6
-1.4
-1.2
-1
-0.8
-0.6
-0.4-0.2
0
-0.8 -0.6 -0.4 -0.2 0
eng(MPa)
eng
Stress strain curve day 16 , 12 %, 50 oC)
Sample 1 Sample 2 Sample 3
y = 0.4088x - 0.0121
R = 0.9717
y = 0.3092x - 0.007
R = 0.9898
y = 0.2672x - 0.006
R = 0.9886
-0.045
-0.04
-0.035
-0.03
-0.025
-0.02
-0.015
-0.01
-0.005
0
-0.12 -0.1 -0.08 -0.06 -0.04 -0.02 0
eng(MPa)
eng
Stress strain curve (day 16 , 12 %, 50 oC)
10 %
10 %
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0.00
1.00
2.00
3.00
4.00
5.006.00
7.00
8.00
9.00
0 5 10 15 20 25 30 35
Young'sMod
ulus(E)
Time (Days)
Young's modulus
0.6 % saline water 12 % saline water
26
Only low strain (10%)
portion of curve used forslope (Gent ,2000)
E values drops by morethan 90% in the first fewdays, and then remainnearly constant duringthe rest of the one-month period
Stress values are higher
for 12% salinity ascompared to 0.6%, butbecome almost identical
with more swelling.
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0
100
200
300
400
500
600
700
800
0 5 10 15 20 25 30 35
K(MPa)
Time (days)
Bulk modulus variation with swelling time
0.60% 12%
Kshows approximatelylinear behavior onp-
v
graphWith more swelling,Kis
fluctuating in thebeginning; becomesalmost steady-state after10 days.
K-value in 12 %
concentration is slightlyhigher than the 0.6 %solution.
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KE62
1
)1(2 EG
0.4975
0.498
0.4985
0.499
0.4995
0.5
0.5005
0 10 20 30 40
v
Time (days)
v(t)0.60% 12%
0
0.5
1
1.5
22.5
3
0 10 20 30 40
G(MPa)
Time (days)
G (t)
0.60% 12%
v increases sharply in firstfew days of swelling, andthen becomes steady-state atabout 0.4999.
v follows opposite trend tothat ofE
V dropped in the 4th day ofswelling due to reduction inK
Value of G drops by morethan 90% in first few days,
then remains almostconstant during rest of theswelling period.
G follows same pattern as E
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HVTD vs. swelling time for 35000 and 8500 brinesolution and crude oil at 60oC
Swelling in lower salinity> higher salinity
VT swelling of disc samples >> plate samples, (both oiland water)
H of both elastomers drops down sharply in the firstfew days, then remains almost constant.
Swelling Test
Only low strain (10%) portion of curve used for slope(Gent ,2000)
Stress values are higher for 12% salinity as compared to0.6%, but become almost identical with more swelling.
CompressionTest
Kshows approximately linear behavior onp-v graph
With more swelling, Kis fluctuating in the beginning;becomes almost steady-state after 10 days.
K-value in 12 % concentration is slightly higher than the0.6 % solution.
Bulk Test
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Thank You
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1. Gent, A.N., Lindley, P.B., 1959. The compression of bonded rubberblocks. Proceedings of the Institution of Mechanical Engineers 173, 111122.
2. Gent, A.N., Meinecke, E.A., 1970. Compression, bending and shear ofbonded rubber blocks. Polymer Engineering and Science 10, 4853.
3. Gent, A.N., Henry, R.L., Roxbury, M.L., 1974. Interfacial stresses forbonded rubber blocks in compression and shear. Journal of AppliedMechanics 41, 855859.
4. S.A. Al-Hiddabi, T. Pervez, S.Z Qamar and F.K Al-Jahwari; Analyticalsolution of elastomer seals in oilwells; SQU, 2009.
5. Yeoh, O.H., Pinter, G.A., Banks, H.T., 2002. Compression of bondedrubber blocks. Rubber Chemistry and Technology 75, 549561.
6. Rutger Evers, Dustin Young, Greg Vargus, and Kristian Solhaug,Halliburton; Design Methodology for Swellable Elastomer Packers inFracturing Operations, Offshore Technology Conference, 4-7 May
2009