seminar-2 dec 2011 experimental investigation

7/30/2019 Seminar-2 Dec 2011 Experimental Investigation

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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

3


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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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5


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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.

6


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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

7


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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


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

11


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12(a)

Ela

stomer

T

ubular


Casing/formation

(b)

E

lastomer

Tu

bular

Casing/formation


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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15

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%

16

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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17

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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19


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20

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

21


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22

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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23

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


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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24

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


0

20

40

60

80

100

120

140

0 10 20 30 40

VolumeChange(%)

Days


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


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


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

seminar-2 dec 2011 experimental investigation

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