Sevket Durucan and J Quan Shi Research at Imperial College

Sevket Durucan and J Quan ShiRoyal School of Mines

Imperial College, London

Enhanced Coalbed Methane Recovery and CO2Sequestration in Coal: An Overview of Current

Research at Imperial College

ENVIRONMENTAL AND MINING ENGINEERING RESEARCH GROUP em

First International Forum on Geologic Sequestration of CO2 in Deep, Unmineable Coalseams “Coal-Seq I”

14-15 March 2002, Houston, Texas

PVT behaviour of CO2 and other gas mixturesMatrix swelling/shrinkage effects on permeability and flow

Relative permeability behaviourDiffusion characteristics of gas mixtures

Enhanced Coalbed Methane Recovery/CO2Storage - R&D PRIORITIES

Binary gas sorption behaviourHydrochemistry Modelling tools - upscaling from matrix/cleat to reservoir scale

Rock and Fluid Characteristics

InjectionWell spacingHorizontal vs vertical wells – improved injectivity?Techniques to improve permeability

Storage Capacity and LongevityType and integrity of caprock

Timescale? Leakage (1-10% ? – 100 years ?)Depth? Criteria on mineable/unmineable seams

S. Durucan & JQ Shi, Coal-Seq I, Houston 2002

Stress, pore pressure and wellbore effects

Coalbed Methane Research at Imperial College

Coal Seam ReservoirCharacterisation

DynamicStress-Permeability

Modelling

Laboratory Investigations

Coalbed Methane Flow and Geotechnical Models

Primary Recoverythrough Reservoir

Depletion

Abandoned MinesGas Production

Enhanced Recoveryand

CO2 Sequestration

CBM Simulator Horizontal CBM Well Model

Openhole CavityModel

S. Durucan, RITE CO2 Workshop, Kyoto 2001

An Investigation into the Effects of Matrix Swelling on Coal Permeability for ECBM And CO2 Sequestration Assessment

Development of Advanced Reservoir Characterisation and Simulation Tools for Improved Coalbed Methane Recovery (ICBM) ICSTM-BP-TUD-IFP-DSK-WA

Laboratory investigations into potential matrix swelling mechanisms

Characterisation of sorption and diffusion behaviour of CH4-CO2mixtures in coal

Relative permeability and capillary pressure characterisation of the cleat-matrix structure in coal

Stress-permeability-stimulation characterisation of coals for the flow of CH4-CO2 mixtures

Geostatistical and fractal characterisation and upscaling of natural fractures

Development of a two-phase, multicomponent simulator

Optimisation of enhanced methane recovery and CH4-CO2 storage

S. Durucan, RITE CO2 Workshop, Kyoto 2001

Saar Coalfield: Coal Mines, Power Stations, Gas Network


UK coalfields including:- South Wales- North Derbyshire- Central Scotland

German coalfields including:- the Saar

- Ensdorf Colliery- Warndt/Luisenthal Colliery

French coalfields including:- Lorrainne Basin- Nord Pas de Calais- Ales Basin

Coalfields and Sample Collection


Cleat characterisationSlabs:

- Face Cleat

- Butt Cleat

- Cleat Angle

Cuttings:

- Micro-cleat size

- Cleat Angle

Discrete cleat angle and size distribution

IMAGE

ANALYSIS

Cleat angle

Source: TUD, 2001, ICBM


Stress – PermeabilityRelationship for Coal

Post-failure

Intact coal

0

5

10

15

20

25

10 15 20 25Mean axial strain (millistrain)

Dev

iato

ric s

tres

( MP

a)

0.00

0.01

0.02

0.03

0.04

0.05Effective confinement: 5 MPa

Per

mea

bilit

y (m

d)

permeability

# 6: fractured

stress

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0effective confinement (MPa)

Perm

eabi

lity

(md)

1st loading (pre-failure)1st unloading (post-failure)2nd loading (post-failure)2nd unloading (post-failure)

Stress-permeability-stimulation characterisation for the flow of CH4-CO2 mixtures


1000 1200 1400 1600 1800 2000 2200 24000

0.1

0.2

0.3

0.4

0.5

0.6

Effective Stress (psi)

Perm

eabi

lity

(md)

Durucan Puri et al Somerton

10Perm

eabi

lity

(k),

10-1

5 m

2

Confining Stress (MPa)0 2 4 6 8

0.313

1030

100300

1000Three YardGreat RowCannel Row

Stress - Permeability Relationships for Coal

Post-failure

Intact coal


P(r ,t)e

P(r ,t)w

Finite Element Mesh for Well Inflow

Finite Difference Mesh for Macro-Flow

0

0.5

1

1.5

2

2.5

3

3.5

20 25 30 35 40 45 50 55Mean Effective Stress, MPa

Permeability, md

OH-6-HCOH-5-HCOH-12-HC

Well breakout

Cavity

Stress-permeability-welbore characterisation for the flow of CH4-CO2 mixtures - Hollow Cylinder Testing

-20

0

20

40

60

80

100

0 10 20 30 40 50

Mean Effective Stress, MPa

Stra

in, m

illis

train

0

0.5

1

1.5

2

2.5

Perm

eabi

lity,

md

Permeability Bore Strain

Radial 1

Radial 2


Matrix Shrinkage and Swelling Effect of Gas Sorption

-400

-200

0

200

400

600

800

1000

0 500 1000 1500 2000 2500

Pressure, psi

Mic

rost

rain

MethaneHeliumCO2

Source: Seidle and Huitt, 1995


Pore Pressure – Permeability Behaviour of Coalbed Reservoirs (Primary CH4 Production)

Effective horizontal stress as a function of

initial reservoir pressure

Permeability rebound as a functionof initial reservoir porosity and pressure


-600-500-400-300-200-100

0100

250 500 750 1000 1250 1500 1750Reservoir pressure (psi)

Cha

nge

in e

ffect

ive

horiz

onta

stre

ss (p

si)

p0 = 1154 psi

p0 = 1750 psi

0.1

1.0

10.0

250 500 750 1000 1250 1500 1750Reservoir pressure (psi)

k/k0

p0 = 1154 psi

p0 = 1750 psi

Pore Pressure – Permeability Behaviour of Coalbed Reservoirs (Primary CH4 Production)

San Juan Fairway Well B#1Data Source: Palmer and Mansoori, 1996

San Juan, Valencia Canyon WellsData Source: Mavor and Vaughn, 1997

The reservoir permeability shows a strong

rebound with reservoir pressure reduction


00.250.5

0.751

1.251.5

1.752

500 700 900 1100 1300 1500Reservoir pressure (psi)

k/k0

history matched permeability response curve

IC model (METSIM)

stress effect only

0

4

8

12

16

20

24

28

0.2 0.4 0.6 0.8 1.0p/p0

k/k0

VC 32-1

well test IC model (METSIM)

Mavor and Vaughn(VC 32-1)

VC 32-4

VC 29-4

Pore Pressure – Porosity/Permeability Behaviour of Coalbed Reservoirs (Gas Desorption)

Re-adsorption of CO2 in coal could potentially have an impact on coal

porosity/permeability, thus reducing CO2 injectivity.


0.1

1.0

10.0

100.0

100 300 500 700 900 1100 1300 1500Reservoir pressure (psi)

k/k0

90% CH4 +10% CO2

100% CO2

Relative permeability and capillary pressure characterisation of the cleat-matrix structure

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0.90

1.00

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4

Gas Saturation

Rel

ativ

e P

erm

eab

ilit

yGas

Water

Watson Head UK - opencast coal

Critical Saturation (Sgcrit) Range = 0.2 - 0.3Absolute Permeability Range = 10 - 20 mDPorosity Range = 1.8 - 4.0 %


CO2 Injection Experiments: Methane and Water Production

520 bar, low temperature autoclave

for large samples

Results on CO2-injection and CH4/ H2O- production

Coal samples: original and prepared

Conditions during the experiments

Source: TUD, 2001, ICBM



Pore-Diffusion Model

0

20

40

60

80

100

0 0.5 1 1.5 2 2.5 3Normalised injected volume

CH4

con

cent

ratio

n (%

)

30

40

50

60

70

80

90

Out

flow

rate

(%

of i

njec

tion

rate

)

concentration

outflow rate

CH4-CO2 Simulator Development

Large Core CO2 Injection Tests: Model Predictions vs Laboratory Data

29 Partners in 9 European Countries

• Facilitate European Research Collaboration,

• Map European Centres of Excellence,

• Access and Define R&D Strategy,

• Facilitate Exploitation and Dissemination of Results,

• Provide Information to Assist Policy Making,

• Develop Training Material and Educational Activities

• Assess best Practice

• Increase Public Awareness

CARBON DIOXIDE SEQUESTRATION TECHNOLOGY NETWORK

(CO2NET)

ENERGY, ENVIRONMENT and SUSTAINABLE DEVELOPMENTS. Durucan & JQ Shi, Coal-Seq I, Houston 2002

CO2NET MEMBER PROJECTSR&D

GESTCO – European survey of geological sinks

ICBM - ECBM

NASCENT – Natural Analogues

AZEP – Gas seperation

NGCAS – Geological storage and risk assessment

GRACE – Capture and cost reduction

Demonstration

SACS – Saline Aquifers

RECOPOL - ECBM

WEYBURN - EOR


Sevket Durucan and J Quan Shi Research at Imperial College

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