1 26-Oct-15

Gas Injection in Fractured Carbonate Rocks

Hassan Karimaie (NTNU)

2 26-Oct-15

Overview

Background

Matrix / fracture system in fractured reservoirs

This research

Motivation and main research question

PVT and core properties

Experiments and simulation

Methodology

Experimental set-up and procedure

Experimental results

Tertiary gas-oil gravity drainage in fractured porous media

Conclusions

3 26-Oct-15

Background

Unique feature of NFR:

Early breakthrough of injected fluid

More uniform fluid composition

Small pressure drop

Absence of transition zone

Fracture

Matrix

Invaded Zone

Oil

Water

or

Gas

4 26-Oct-15

Analogue model

5 26-Oct-15

Motivation and main reserach question

Recovering the remaining oil in the matrix after

waterflooding by:

Equilibrium gas injection in reservoir condition

Tertiary case with wettability and Composition

effect

Re-pressurization (effect of IFT reduction)

Non-equilibrium gas injection (CO2 and C1)

6 26-Oct-15

Fluid composition (85 0C)

Pressure

(bar)

Oil Phase

C1 C7

Gas phase

C1 C7

220 0.7034 0.2966 0.8825 0.1175

210 0.6690 0.3310 0.8967 0.1033

200 0.6375 0.3625 0.9073 0.0927

7

Fluid properties (PVT measurements)

200

210

220

230

240

250

0.96 0.97 0.98 0.99 1 1.01 1.02 1.03 1.04 1.05 1.06R e l a t i v e v o l u m e

P r

e s

s u

r e

(b

a r

)

85 C

Pb

8 26-Oct-15

1.95

2

2.05

2.1

2.15

2.2

2.25

2.3

195 200 205 210 215 220 225

Pressure (bar)

Oil

fo

rmat

ion

vo

lum

e fa

cto

r

Fluid properties (PVT measurements)

9 26-Oct-15

Fluid properties (PVT measurements)

0

0.1

0.2

0.3

0.4

0.5

195 200 205 210 215 220 225Pressure (bar)

Den

sity

(g

/cm

3)

Oil density

Gas density

10 26-Oct-15

222

224

226

228

230

232

234

236

40 60 80 100 120

Temperature (oC)

Bu

bb

le p

oin

t p

ress

ure

(b

ara)

0

50

100

150

200

250

300

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

C1, mole %

Pre

ssu

re,

bara

0

50

100

150

200

250

300

Pc

Tc

Fluid properties-EOS model

0

50

100

150

200

250

300

-50 0 50 100 150 200 250

Temperature, )

Pre

ssu

re (

bar

)

Tuned EOS Model

Non-Tuned EOS Model

C

11 26-Oct-15 26-Oct-15

Fluid properties-IFT measurements

l

Pendant drop of heptane rich phase surrounded by methane rich phase

220 bara 210 bara 200 bara

85 0C

de

ds

Gas

Oil

de

ds

Gas

Oil

)(

2

VLe

l

gd

esdd /

l: function of R

Pressure

(bara)

220 210 200

IFT

mN/m

0.15 0.37 0.68

12 26-Oct-15

IFT: Experiment vs. simulation

0

0.2

0.4

0.6

0.8

1.0

190 200 210 220 230

Pressure, bara

IFT

, m

N/m

Measurement

Simulation based on SRK-

Peneloux EOS tunned to

experimental data

Simulation based

on non-tuned SRK-

Peneloux EOS

)(4

1

vilii yxP

Simulation: Weinauge and Katz

13 26-Oct-15

PVT properties

Pressure

(bara)

Oil density

(g/cm3)

Gas density

(g/cm3)

Bo IFT

mN/m

220 0.407 0.223 2.28 0.15

210 0.433 0.198 2.1 0.374

200 0.452 0.178 1.98 0.686

14 26-Oct-15

Properties of porous media

Properties Chalk

(water wet)

Limestone

(mix wet)

Permeability

(mD)

5.2 14.0

Porosity % 44.0 23.0

Length (cm) 19.6 18.0-19.0

Pore Volume

(cm3)

98-99 47.0-50.0

Hc @ 0.37

mN/m

3.48 cm 4.8 cm

Hc @ 0.15

mN/m

1.41 cm 1.97 cm

15 26-Oct-15

Properties of porous media

Sample No. Swi

%

Sor

%

Sw @

krw= kro

1 15.6 24.3 33

2 25.8 31.7 46

3 18.7 32.4 34

4 18.9 32.7 40

5 20.4 31.8 39

Moldic and vuggy porosity (blue)

Sparitic calcite cement (white)

-10

-5

0

5

10

15

0 0.2 0.4 0.6 0.8 1

Sw

Pc (

bar)

Drainage

Imbibition

16 26-Oct-15

Exp. No Water

injection

Equilibrium

gas

injection at

210 bar

(IFT=0.37

mN/m)

Equilibrium

gas

injection at

220 bar

(IFT=0.15

mN/m)

CO2

injection

C1

injection

1-Chalk

(water wet)

. . . . ------

2-Chalk

(water wet)

. . . ------ .

3-Limestone

(mix wet)

. . . . ------

4-Limestone

(mix wet)

. . . ------ .

Summary of experiments

17 26-Oct-15

2 mm

fracture

42 mm

20

cmmm

Stainless

steel tube Core

2 mm

fracture

42 mm

20

cm38

Stainless

steel tube Core

2 mm

fracture

42 mm

20

cmmm

Stainless

steel tube Core

2 mm

fracture

42 mm

20

cm38

Stainless

steel tube Core

Methodology in gas injection experiment :

Sealing the fracture

• Special alloy (woods metal)

• Melting point=67 0C

Re-opening the fracture

Methodology:Experimental Set-up

18 26-Oct-15

1- Quizix pump. 8- Sealing material accumulator

2,3-Isolated cells 9- Back pressure regulator

4- Isolated constant temperature tube 10- Condenser

5- Pressure transmitter 11-Seperator

6-Steel tube containing matrix and fracture. 12-Gas wet test meter

7- By-pass system 13-Gas chromatograph

Methodology:Experimental Set-up

19 26-Oct-15

CO2 injection in water-wet sample

0

0.2

0.4

0.6

0.8

1

0 1 2 3 4 5 6 7Time (day)

Recovery

, fr

acti

on o

f O

OIP

Equ. Gas, 210 bar

IFT=0.37mN/m

Equ. Gas, 220 bar

IFT=0.15 mN/mCO2 injection

Water

injection

13%

6%

6%

20

C1 injection in water-wet sample

26-Oct-15

0

0.2

0.4

0.6

0.8

1

0 2 4 6 8 10 12

Time (day)

Rec

ov

ery

, fr

acti

on

of

OO

IP

C1 injection

Water

injection

Re-pressurization

Equ. Gas, 220 bar

Start of Equ.

Gas, 210 bar

16%

5%4%

21

CO2 vs. C1

26-Oct-15

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0 0.5 1 1.5 2 2.5 3 3.5 4

Time (day)

Reco

very

, fr

acti

on

of

OO

IP

C1 injection

CO2 injection

C1 injection

CO2 injection

22 26-Oct-15

CO2 injection in mix-wet sample

0

0.2

0.4

0.6

0.8

1

0 1 2 3 4 5Time (day)

Rec

ov

ery

, fr

acti

on

Water

Injection

Re-pressurization

Eq. Gas, 220 bar

CO2 Injection

Eq. Gas, 210 bar

41%

9%

15%

23 26-Oct-15

C1 injection in mix-wet sample

0

0.2

0.4

0.6

0.8

1

0 1 2 3 4 5 6Time (day)

Rec

ov

ery

, fr

acti

on o

f O

OIP

Eq. Gas, 210 bar

Re-pressurization

Eq. Gas, 220 bar

C1 Injection

Water

Injection 32%

16%

12%

24

CO2 vs. C1

26-Oct-15

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18

0 0.2 0.4 0.6 0.8 1 1.2Time (day)

Rec

ov

ery

, fr

act

ion

C1 injection

CO2 injection

C1

CO2

25 26-Oct-15

Summary of experimental results

Exp

.No

Recovery Mechanism Wettability Water

injection

R.F %

Equilibrium

gas injection

R.F %

Non-equilibrium

gas injection

R.F %

1 Tertiary (water

injection

+GOGD+CO2)

Water-wet 55 19 6

2 Tertiary (water

injection +GOGD+C1)

Water-wet 60 21 4

3 Tertiary (water

injection

+GOGD+CO2)

Mix-wet 8 50 15

4 Tertiary (water

injection +GOGD+C1)

Mix-wet 8 48 12

26 26-Oct-15

Conclusion

1- Gas-oil gravity drainage at low interfacial tension was found to be a

very effective oil recovery method from mix-wet and water-wet

fractured media at both secondary and tertiary injection.

2- Additional oil recovery could be obtained by injection of non-

equilibrium gas, where diffusion and gravity drainage are the key

factors for increased oil recovery.

3- Injection of lean gas such as C1 can aslo improve the oil recovery

significantly.

4- CO2 injection is more efficient compare to C1 injection in fractured

carbonate rock.

27 26-Oct-15 26-Oct-15

• H.Karimaie, G.R. Darvish, E. Lindeberg and O. Torsæter. “Experimental

Investigation of Secondary and Tertiary Gas Injection in Fractured Carbonate

Media”. Journal of Petroleum Science and Engineering (JPSE) Volume 62, Issues

1-2, 15 September 2008, Pages 45-51.

• H.Karimaie and O. Torsæter. “Low IFT Gravity Drainage in Fractured

Reservoirs”. Journal of Petroleum Science and Engineering (JPSE), Volume 70,

Issues 1-2, January 2010, Pages 67-73.

• H.Karimaie and O.Torsæter. "CO2 and C1 Gas Injection for Enhanced Oil

Recovery in Fractured Reservoirs”. SPE 139703. Presented at SPE International

Conference on CO2 capture and storage, New Orlean, Louisiana, USA, 2010.

• A.M. Saidi,. “Reservoir Engineering of Fractured Reservoirs”. Total 1987

• T.D. Van Golf-Racht,. “Fundamentals fo Fractured Reservoirs”. Elsevier, 1982.

References:

28 10/26/2015 9:01 AM

Thank you !

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