CO2 Injection Paper

8/13/2019 CO2 Injection Paper

1/15

Pressure Buildup atCO2 Injection Wells

Sally M. Benson

Lawrence Berkeley National Laboratory

Berkeley, California 94720

Second Annual Conference on Carbon Sequestration

May 5-8, 2003

Main Menu Technical Sessions Plenary Sessions Poster Presentations Participants


2/15


3/15

Applications

Estimation of injection pressures at CO2

injection wells Pressure transient analysis at CO2 injection

wells

Evaluation of the influence of CO2/water/rock

interactions on formation permeability

Characterization and monitoring of CO2sequestration processes and progress


4/15

Physical Processes During Injection

of CO2 into Water Immiscible displacement of water

by CO2 Relative permeability effects

Capillary pressure effects

Adverse mobility ratio

water>>CO2

Pressure and temperature

dependent CO2 viscosity and

density Partitioning of CO2 into the

water phase

Partitioning of water into theCO2 phase

Relative Permeablity

0

0.2

0.4

0.6

0.8

1

0 0.25 0.5 0.75 1

sw

0

0.2

0.4

0.6

0.8

1krCO2

krw

Relative Permeablity

0

0.2

0.4

0.6

0.8

1

0 0.25 0.5 0.75 1

sw

0

0.2

0.4

0.6

0.8

1krCO2

krw


5/15

Implications for Pressure Buildup

During CO2 Injection

Relative permeability of CO2

and water will vary in theregion behind the CO2-front

Saturation of CO2 and

water will vary in the regionbehind the CO2- front

Saturation Distribution

0

0.2

0.4

0.6

0.8

1

0 50 100 150 200r (m)


0

0.2

0.4

0.6

0.8

1

0 50 100 150 200r (m)

Sharp Front

Relative Pemeability

0

0.2

0.4

0.6

0.8

1

0 50 100 150 200r (m)

Relative Pemeability

0

0.2

0.4

0.6

0.8

1

0 50 100 150 200r (m)


6/15

A New Approximate Analytical Solution

For Pressure Buildup Assumptions

Buckley-Leverett type

displacement

Vertical equilibrium

Horizontal reservoir

Homogeneous reservoir

Neglect capillary pressure

(not required)

Slightly compressible fluid

Based on technique

developed by Benson(1984, 1987)

rw rf

qCO2

hk,ct,


7/15

New Pressure Buildup Solution

Solution consists of two components

Steady state pressure buildup behind the CO2

front (ps.s.) Pressure transient buildup outside of the front

(pt)

)4(4),(

),(

),(

),(

),(

2),(

),(),(),(

2

..

..

2

2

2

2

2

22

kt

cr

Eikh

q

trp

r

dr

trk

tr

tr

trf

kh

q

trp

trptrptrp

twf

CO

wCO

ft

r

CO

r

r CO

COCO

wss

ftwssw

CO

f

w

=

=

+=


8/15

Evaluating p s.s.

r

dr

trk

tr

tr

trf

kh

qtrp

CO

f

w r

CO

r

r CO

COCO

wss ),(

),(

),(

),(

2),(

2

2

2

22

..

=

Density Distribution

After 30 Days of Injection

700

725750

775

800

0 50 100 150

r (m)

CO2

< 10% variation

Density Distribution


700

725

750

775

800

0 50 100 150

r (m)

CO2

< 10% variation

Viscosity Distribution


6.0E-05

6.5E-057.0E-05

7.5E-05

8.0E-05

0 50 100 150

r (m)

CO2

< 10% variation

Viscosity Distribution


6.0E-05

6.5E-05

7.0E-05

7.5E-05

8.0E-05

0 50 100 150

r (m)

CO2

< 10% variation

Assign average values for and behind the front


9/15

Multi-phase Flow Behind the CO2 Front

22

2

2

2

2

CO

CO

sCO

CO

CO

CO

ss

f

h

tqr

=

)(

)(1

1)(

22

22

2

22

COrw

wrCOCOw

CO

COCO

sk

skqq

qsf

CO

w

+

=+

=

Fractional Flow of CO2

0.00

0.20

0.40

0.60

0.80

1.00

0 0.2 0.4 0.6

sCO2

sf


0.00

0.20

0.40

0.60

0.80

1.00

0 0.2 0.4 0.6sCO2

sf

Buckley-Leverett Solution


0

0.2

0.4

0.6

0.8

1

0 50 100 150 200r (m)


0

0.2

0.4

0.6

0.8

1

0 50 100 150 200

r (m)

Buckley-Leverett Solution


10/15

Evaluating p s.s.

r

dr

trk

trf

kh

qtrp

f

w CO

r

r r

CO

CO

COCO

wss =),(

),(

2

),(

2

2

2

22

..

CO2 Saturation

After 30 Days

0.0

0.5

1.0

0 50 100 150

r (m)

Numerical

Buckley Leverett

CO 2 Saturation

After 30 Days

0.0

0.5

1.0

0 50 100 150

r (m)

Numerical

Buckley Leverett

fCO2/krCO2 30 Days

0.00

10.00

20.00

30.00

40.00

0 50 100 150

r (m)

fCO2/krCO230 Days

0.00

10.0020.00

30.00

40.00

0 50 100 150

r (m)

Assign a linear variation for fCO2/krCO2 behind the front


11/15

Approximate Analytical Solution),(),(),( .. trptrptrp ftwssw +=

+=

+=

80907.ln4

),(

ln11ln2

),(

2

..

2

2

2

2

2

22

ftwCO

wCOft

w

f

wf

w

rr

CO

w

f

CO

COCOwss

rckt

khqtrp

rr

rrr

k

f

rr

kh

qtrp

fCO

rsCO2=

Qt

h

fCO2

sCO2 sCO2


0.00

0.25

0.50

0.75

1.00

0 0.2 0.4 0.6

sCO2

sf


0.00

0.25

0.50

0.75

1.00

0 0.2 0.4 0.6s

CO2

sf


12/15

Typical Pressure Buildup

195

197

199

201

203

0 30 60 90 120 150 180

time (days)

Pressure

(bars)

k = 100 mD

h = 20 mqCO2= 15.86 kg/s

initial pressure = 150 bars

CO2= 6.5 e-5 Pa-s

CO2= 715 kg/m3porosity = 0.12195

197

199

201

203

0 30 60 90 120 150 180

time (days)

Pressure

(bars)

k = 100 mD

h = 20 m

qCO2= 15.86 kg/s

initial pressure = 150 bars

CO2= 6.5 e-5 Pa-s

CO2= 715 kg/m3

porosity = 0.12


13/15

Semi-log Plot

195

197

199

201

203

0.10 1.00 10.00 100.00 1000.00

time (days)

Pressure(bars)

0.5

0.7

0.9

1.1

1.3

1.5

S

lope(ba

rs)

Pressure Buildup

Slope

195

197

199

201

203

0.10 1.00 10.00 100.00 1000.00

time (days)

P

ressure

(bars)

0.5

0.7

0.9

1.1

1.3

1.5

Slope(b

ars)

Pressure Buildup

Slope

kh

qm

CO

COCO

2

22

4

=


14/15

How Good Is the Approximate Solution?

Comparison to numerical simulation generated using

TOUGH2 (Pruess et al., 2001)

Pressure Buildup

190

195

200

205

210

0.01 0.10 1.00 10.00 100.00time (days)

Pressure(bars)

Numerical

sf=0.225

sf=0.23

Pressure Buildup

190

195

200

205

210

0.01 0.10 1.00 10.00 100.00time (days)

Press

ure(bars)

Numerical

sf=0.225

sf=0.23


15/15

Summary A new approximate analytical solution for

predicting pressure buildup during CO2 injection

into brine formations has been developed

Comparison to numerical simulations verifies the

applicability of this solution to typical CO2

sequestration scenarios Pressure transient analysis may provide a useful

tool for monitoring CO2 sequestration operations,

including: Validation of multiphase flow processes

Front tracking

Detection of permeability changes from CO2 injection

Documents

CO2 Injection Paper