Enhanced Coalbed Methane Recovery and CO2 Storage in Coal … · 2017-10-31 · 1 Enhanced Coalbed Methane Recovery and CO 2 Storage in Coal Seams Sevket Durucan Department of Earth

1

Enhanced Coalbed Methane Recovery and CO2 Storage in Coal Seams

Sevket Durucan Department of Earth Science and Engineering

Imperial College London

APEC Seminar, AIST, Tsukuba, 7 December 2007mINING AND ENVIRONMENTAL ENGINEERING RESEARCH GROUP

Background

Coalbeds as both the reservoir and source rock

OUTLINE

Retention and release of gas in coal

Coal permeability, dynamic permeability modelling in coalbedreservoir simulation

Reservoir simulation of enhanced Coalbed Methane recovery and CO storage in coal seams

APEC Seminar, AIST, Tsukuba, 7 December 2007

CO2 storage in coal seams

Conclusions

2

World Carbon Dioxide Storage Options

Deep Ocean

Saline Aquifers

Unminable Coal Seams >15 Gt CO

Depleted Oil Reservoirs

Depleted Gas Reservoirs

Unminable Coal Seams >15 Gt CO2

APEC Seminar, AIST, Tsukuba, 7 December 2007Source: USGS

Major Coal Basins


3

Major Coal Basins


Major Coal Basins and Methane ResourcesContinent Country Coal Resources Methane Resources

x 109 tonnes x 1012 m3

Europe and Belgium 0.075the Russian France 0.600Federation Germany 320 2.85Federation Germany 320 2.85

Hungary 0.085Poland 160 2.85Russia 6,500 17-113Ukraine 140 1.7UK 190 1.7

North America Canada 7,000 5.7-76USA 3,970 11

Asia China 4,000 30-35India 160 0.85


Indonesia 6Kazakhstan 170 1.13

Australia 1,170 8.5-14

Africa 150 0.85

World Totals ~25,000 ~84 - 262Source: ARI, 1992

4

Underground Methane Drainage Practice

Coalbed Methane Technology

Methane Extraction from Coal Seams: Well Technology


Coal as a Reservoir Rock: Structure

Uniform and orthogonal fracture (CLEAT) structure


microcleat

5

Coal as a Reservoir Rock: Structure

f l t

butt cleat

adsorbed gas

Coal Matrixcontaining

pores

face cleat

Macropores > 50 nm

M 2 50

microcleat


free gas

CH4

Mesopores 2 – 50 nm

Micropores < 2 nm

Cleat system (2mm - 25 mm)

Pore surface area 20 – 200 m2

Coal as a Reservoir Rock – Gas Retention

butt cleat

adsorbed gas

Coal Matrixcontainingmicropores

face cleat

8

12

16

20

s C

onte

nt, m

3 /t

CH4 adsorption isotherm


free gas

CH4 0

4

0 1 2 3 4 5 6 7 8Pressure, MPa

Gas

6

Coal as a Reservoir Rock: CH4 / CO2 Retention in Coal - Adsorption Isotherm

COt)

1,000

Pressure (MPa)0 1.4 2.8 4.2 5.6 7

CO2

75%CO2 25%CH4

CH4

Gas

con

tent

(m3 /t

10

15

5

0

800

600

400

Gas

Con

tent

(sc

ft/t

onne

)


Pressure (MPa)

0 200 400 600 800 1,000 1, 200Pressure (psi)

0

200

pPpVV+

=L

LLangmuir equation:

Enhanced Coalbed Methane Recovery (ECBM)two principal methods of ECBM, namely N2 and CO2 injection (inert gas stripping and displacement sorption respectively)

injection of nitrogen reduces the partial pressure of methane in the reservoir, th t th d ti ith t l i th t t l ithus promotes methane desorption without lowering the total reservoir pressure

20

25

m3 /t

)

CH4 7% moist. coal CO2

3 /t)

15

coal can adsorb approximately two to six times as much CO2 by volume as methane, therefore, the assumption has been that the CO2 injection stores 2-6 moles of CO2 for every mole of CH4 desorbed.


Pressure (MPa)0 4 8 122 6 10 16

10

5

15

20

014

Gas

con

tent

(m

N2 7% moist. coal

Pressure (MPa)0 1.4 2.8 4.2 5.6 7

75%CO2 25%CH4

CH4

Gas

con

tent

(m3

10

15

5

0

7

CoalSite

Durango

Tiffany Unit

Florida River Plant

McElmoD

Simon Pilot

San Juan BasinSimon Pilot

Colorado

NewMexico

Sweet

COLORADONEW MEXICO

SpotFarmington

Overpressured:Sw = 1.0

Allison Unit

Tiffany UnitDomeCO2 Field


Underpressured:Sw < 1.0

Underpressured:Sw = 1.0

Scale, miles0 10 20

Amoco Simon N2 Injection Pilot

Simon Pilot

Nitrogen

1,600

1,200

800

Start NitrogenInjection

Total Gas

End NitrogenInjection

Rat

e M

scf/

D o

r ST

B/D


Natural Gas

1988 1989 1990 1991 1992 1993 1994 1995

400

0Water

NaturalGas

Gas

/Wat

er R

Source: Wong, Gunter, Law and Mavor, 2000

8

CoalSite

Durango

Tiffany Unit

Florida River Plant

McElmoD

Simon Pilot

San Juan BasinTiffany Unit

Colorado

NewMexico

Sweet

COLORADONEW MEXICO

SpotFarmington

Overpressured:Sw = 1.0

Allison Unit





Scale, miles0 10 20

BP Tiffany Unit N2 Injection (Full Scale Commercial Pilot)

12 N2 injector wells,

34 CH production wells

9 Years of primary production,

Tiffany Unit

34 CH4 production wells,

N2 injection started in January 1998,

4-6 fold increase in production

early N2 breakthrough

Source: Reeves and Peckot, ARI, USCBM Symp, 2001

Nitrogen Injection Suspended100000


Nitrogen Injection Suspended

Water Measurement Discrepency

Water ProductionGas Production

Nitrogen Injection

100

10

1000

10000

1May-90 Sep-91 Jan-93 Jun-94 Oct-95 Mar-97 Jul-98 Dec-99 Apr-01 Sep-02

Rat

e, M

cfd

or B

pd

9

BP Tiffany Unit N2 Injection (Full Scale Commercial Pilot)

Nitrogen Injection Suspended

Water ProductionGas Production

100000

Tiffany Unit

Water ProductionNitrogen Injection

100

1000

10000

Rat

e, M

cfd

or B

pd


Source: Reeves and Pecot, ARI, USCBM Symp, 2001

Water Measurement Discrepency

10

1May-90 Sep-91 Jan-93 Jun-94 Oct-95 Mar-97 Jul-98 Dec-99 Apr-01 Sep-02

CoalSite

Durango

Tiffany Unit

Florida River Plant

McElmoD

Simon Pilot

San Juan BasinAllison Unit

Colorado

NewMexico

Overpressured:Sw = 1.0Sweet

COLORADONEW MEXICO

SpotFarmington

Allison Unit



Scale, miles0 10 20



10

Burlington Resources Allison Unit CO2 Injection

4 CO2 injector wells,


6 Years of primary production (1988/89 – 1995),

Allison Unit

McElmoDomeCO2 Field


CO2 injection started in May 1995,

reduced CO2 injectivity with time

No significant CO2 breakthroughSource: Reeves and Pecot, ARI, USCBM Symp, 2001

Alb t R h C il F Bi V ll CO I j ti


Alberta Research Council, Fenn Big Valley CO2 Injection

coal swelling and reduced permeability observed

Field micro-pilot testing started in 1997

Source: Wong and Gunther, 1999Law, Van der Meer, Mavor and Gunter 2000

Burlington Resources Allison Unit CO2 Injection

Allison Unit

McElmoDomeCO2 Field

APEC Seminar, AIST, Tsukuba, 7 December 2007Source: Reeves, ARI, Coal-Seq Forum, 2002

11

Coal Permeability and Gas Flow

“… contrary to what is usually supposed, solid coal is extremely airtight, and lets very little air or gas through, even with a driving pressure of a whole atmosphere.”

Ivor GRAHAM, 1916

“….that the rate of gas flow through the coal is a function of thedifference in partial pressure of methane along the flow path. Therefore, the emission of methane from a lump of coal is not


, pdependent on the total external pressure, but upon the partial pressure of the methane in the atmosphere and the pressure of the gas in coal.”

Ivor GRAHAM, 1919

Strength, Elastic and Flow Properties of Coal

Coal structure is highly elastic

LimestoneSandstoneWeak

Reservoir S d t

Coal(Various) Shale

fractures matrix

0.86 - 3.9 35 - 5510- 200.4 – 1.8

Young’s Modulus, E

(GPa)

Sandstone( )

5 - 70

10

15

20

25

Stre

ss (M

Pa)


Coal permeability is• Anisotropic

• Highly stress dependent

0

5

10

0 10 20 30 40 50 60Axial Strain (millistrain)

Axia

l S

CAYDAMARBARNSLEYCOCSHEADBANBURYDUNSILDEEP HARD

12

Stress Effects and Permeability

0.5

0.6

md) Durucan Puri et al Somerton

10-1

5 m

2

3001000

Three Yard


1000 1200 1400 1600 1800 2000 2200 24000

0.1

0.2

0.3

0.4

Effective Stress (psi)

Perm

eabi

lity

(m

•Intact coal

10

Perm

eabi

lity

(k),

1

Confining Stress (MPa)0 2 4 6 8

0.313

1030

100300

Great RowCannel Row

•Fractured coal

Field Experience: San Juan Basin Field Permeability Behaviour

Pressure dependent permeability multiplier

2345678

k / k

(p =

800

psi

)


(after McGovern, 2004)

012

0 100 200 300 400 500 600 700 800 900Reservoir pressure (psia)

13

Pore Pressure Effects on Permeability: Matrix Shrinkage and Swelling

Lorraine

4000

6000

8000

tric

stra

in

ostra

in)

CO2

CH

fractures matrix

1

-2000

0

2000

0 1 2 3 4 5 6 7 8Cell pressure (MPa)

Vol

umet

(mic

ro CH4

He

pP

pV+

=

L

Lεsαs


0.001

0.01

0.1

0 1 2 3 4Pore pressure (MPa)

Per

mea

bilit

y (m

D)

CO2 permeability (Lorraine)

CH4 permeability (Lorraine)

CO2 permeability (Schwalbach)

Primary and Enhanced Coalbed Methane Recovery Permeability Model


14

Model for Changes in Coalbed Permeability During Primary Recovery

)(3 0f σ−σ−= cekkFlow

Bundled matchstick model

bk3

121=)(

00f= ekk

b

a

σ – σ0 - changes in effective horizontal stress (after Seidle et al., 1992)

cf – cleat volume compressibility

a12


)1(3)()(

10

00 ν−−α

+−ν−

ν−=σ−σ

VVEpp S

E – Young’s modulus

ν – Poisson’s ratio

αS – shrinkage coefficient

V – adsorbed gas volume

shrinkage termcompaction term

Schematic Permeability Behaviour

rbpp >0σ−σ0

A

150

200

250

300

ent (

SC

F/to

n)

)(1)1(3

)(0

00 ppVVE S −

ν−ν

−ν−−α

=σ−σ

rbpp <0

σ−σ0 BA

B

VL = 448 SCF/ton1/b = 525 psi

p0prc0

prb

p


0

50

100

0 300 600 900 1200 1500 1800Sorption pressure (psia)

Gas

con

te

p0 prc0

prb

p

pprb

15

Model Validation: US San Juan Basin History MatchValencia Canyon Wells: Steady increase in permeability

20

25well test

1 5

2history matched permeability

Fairway B1 “boomer” Well: Strong permeability rebound

2p0 = 1500 psi

0

5

10

15

0.2 0.4 0.6 0.8 1p/p0

k/k 0

VC 32-4

VC 29-4VC 32-1

VC 32-1 (Mavor and Vaughn)

20

25well test

0

0.5

1

1.5

500 700 900 1100 1300 1500

Reservoir pressure (psi)

k/k0

response curve at fairway B1(Palmer and Mansoori)


0

0.5

1

1.5

500 700 900 1100 1300 1500

Reservoir pressure (psi)

k/k0

Present model

P & M model

p0 = 1500 psi

φ0 = 0.00085 METSIM

0

5

10

15

20

0.2 0.4 0.6 0.8 1.0p/p0

k/k 0

VC 32-1

present studyMavor and Vaughn

VC 32-4

VC 29-4

METSIM

Permeability Model For Enhanced Recovery

)(30

0f σ−σ−= cekk Cleat permeability

)1(3)()(

10

00 ν−−α

+−ν−

ν−=σ−σ

VVEpp S

Primary recovery

Enhanced recovery

Shrinkage/swelling term


aSj – shrinkage/swelling coefficient for gas component j

)()1(3

)(1 0

100 j

n

jjSj VVEpp −α

ν−+−

ν−ν

−=σ−σ ∑=

16

Imperial College in-house ECBM Simulator METSIM2

• 3D two-phase Darcy flow in cleats, Fickian diffusion in matrix (allows for bidisperse diffusion)

• multi-component gas mixture (CH2, CO2, N2)

• matrix shrinkage/swelling effects one permeability

• mixed gas sorption and diffusion


• extended Langmuir model

Yubari Field Pilot, Hokkaido, Japan

(after Fujioka, 2006)


• In a mountainous national forest area

• Bounded by four major faults

17

Yubari Field Test

Three stages

• CO2 injection huff-puff test (well 1 CO )IW-1, 7.5 tons CO2)

• Multi-well CO2 injection tests• 2004 (16 days, 35.7 tons CO2)• 2005 (42 days, 115.4 tons

CO2)

• N2 flooding test• 2006 N flooding (9 days 32


• 2006 N2-flooding (9 days, 32 tons N2)

• 2006 Pre- and Post-N2flooding CO2 injection • Well tests prior to the test and

after 2004 CO2 injection• 1 -> 0.08 md

Multi-well test: Production and injection rates

300

400

m3 /d

)

1600

2000

3 /d)

CO2 injection rate

CO2 Injection and N2 Flooding TestField Injection and Gas Production Rates

2004:

0

100

200

300

20-Aug 1-Sep 13-Sep 25-Sep 7-Oct 19-Oct 31-Oct

2005

Gas

pro

duct

ion

rate

(m

0

400

800

1200

CO

2 inj

ectio

n ra

te (m

3

production rate

CO2 & N2 injected and gas & water production rates 7 800

CO2 (ton) N2 (ton)

2005

2004:• 15 days injection• 1.8 – 2.9 tones CO2/day

(1 ton = 506 std. m3)

2005:• 40 days injection


0

1

2

3

4

5

6

11-Apr 18-Apr 25-Apr 2-May 9-May 16-May 23-May 30-May 6-Jun2006

CO

2 & N

2 inj

ecte

d (to

n) /

wat

er p

rodu

ctio

n ra

te (m

3 /d)

0

100

200

300

400

500

600

700

Gas

pro

duct

ion

rate

(m3 /d

)

( ) ( )Gas (m3) Water (m3)

40 days injection• 1.7 – 3.5 tones/day

Low production rates:< 400 m3/day

18

Reservoir Simulation of the 2006 N2Flooding Test

Simulated N2/CO2 injection wellblock

N2 flooding: downhole tubing pressure

14

15

16

ssur

e (M

Pa)

model BHP

Simulated injection wellblock pressure & permeability

13

14

15

16

/ BH

P (M

Pa)

10

100

rmea

bilit

y (m

d)

BHP

pressure

end of N2

fl di

2 2 jpermeability and BHP

11

12

13

0 2 4 6 8 10

N2 injection time (day)

Tubi

ng p

res

Simulated vs. field N2injection BHP


10

11

12

13

0 4 8 12 16 20 24Elapsed time from the start of N2 flooding (day)

Iwel

lblo

ck /

0.1

1

Wel

lblo

ck p

epermeability

flooding

start of CO2

injection

Model Prediction vs Field Data: Pre- and Post- N2 Flooding CO2 Injection Rates

30002

model field (injected amount) field (24-hour rate)

Pre-N2 flooding

Post N2 flooding CO 2 injection rate 20000

0

600

1200

1800

2400

3000

10-Apr 15-Apr 20-Apr 25-Apr 30-Apr 5-May 10-May

2006

Rec

orde

d da

ily a

mou

nt in

ject

ed (m

3 )/ C

O2

inje

ctio

n ra

te (m

3 /d)

Post-N2 flooding

0

4000

8000

12000

16000

20000

0 2 4 6 8 10Injection time (day)

CO

2in

ject

ion

rate

(m3 /d

)

model

field


N2 flooding temporarily improved CO2 injectivity, which declined quickly back to the pre-flooding level (~ 3 tones/ day) after two days.

19

Concluding remarks

• Coalbed reservoirs have unique characteristics: storage, transport and production mechanisms, permeability b h ibehaviour.

• Considerable advances in the reservoir simulation of ECBM, especially in permeability modelling have been made.

• While matrix shrinkage is desirable during primary recovery, CO2 matrix swelling can have a severe impact on coalbed permeability and well injectivity


permeability and well injectivity.

• Long term fate of injected CO2 in coalbeds is uncertain, as CO2, especially at supercritical conditions, reacts with the reservoir rock and fluids.

Enhanced Coalbed Methane Recovery and CO2 Storage in Coal … · 2017-10-31 · 1 Enhanced Coalbed Methane Recovery and CO 2 Storage in Coal Seams Sevket Durucan Department of Earth

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