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Presentation FRIA: FE2 approach for the modelling of coupled hydro-mechanical behaviour of partially saturated coalbeds

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(1)

PhD Thesis Research

FE

2

approach for the modelling of coupled hydro-mechanical behaviour

of partially saturated coalbeds

François B

ERTRAND

Supervised by: Frédéric C

OLLIN

University of Liège

(2)

Introduction

Coalbed methane

NORTH SEA GERMANY THE NETHERLANDS FRANCE LUX. Brussels Antwerpen Hasselt Mons Liege Namur 50 km

3°E 4°E 5°E 6°E

50°N 51°N

N

BELGIUM

Figure:

Map of the outcropping or shallow

subsurface coal basins (shaded area) in and around

Belgium. Modified after [Piessens and Dusar, 2006].

6 to 9 billions tons of coal

in the walloon basement

100 to 300 billions m

3

of methane

?

?

10 to 20 billions m

3

of recoverable methane?

(3)

Introduction

Coalbed methane

Coalbed methane (CBM) =

unconventional resource

Source rock (= coalbeds) is also the reservoir for the methane

Coalbed methane

Conventional

reservoir

Seal Source Reservoir

Coal

(4)

Introduction

Coal properties

Coalbeds =

dual porosity systems

Micropores + Macropores

⇐⇒

Matrix + Cleats

Figure:

From Schlumberger Oilfield Glossary

(5)

Introduction

Coal properties

Coalbeds =

dual porosity systems

Micropores + Macropores

⇐⇒

Matrix + Cleats

Figure:

From Schlumberger Oilfield Glossary

Cleat

permeability is directly dependent

on the

width of the cleats.

(6)

Introduction

Challenge

"The influence of

geomechanical processes is an important issue for coalbed

methane recovery and ignoring geomechanical processes may lead to errors in the

evaluation of coalbed methane production." [Gu et al., 2005]

But

Coupled hydro-mechanical behaviour of coalbeds

=

complex + still defeats a comprehensive description

(7)

Introduction

Challenge

"The influence of

geomechanical processes is an important issue for coalbed

methane recovery and ignoring geomechanical processes may lead to errors in the

evaluation of coalbed methane production." [Gu et al., 2005]

But

Coupled hydro-mechanical behaviour of coalbeds

=

complex + still defeats a comprehensive description

Macroscale FE computation

Current models

Phenomenological constitutive models

Laws at macroscale for microscopic phenomena

(8)

Introduction

Challenge

"The influence of

geomechanical processes is an important issue for coalbed

methane recovery and ignoring geomechanical processes may lead to errors in the

evaluation of coalbed methane production." [Gu et al., 2005]

But

Coupled hydro-mechanical behaviour of coalbeds

=

complex + still defeats a comprehensive description

Macroscale FE computation

Current models

FE² method

Modelling at lower scale

Phenomenological constitutive models Microscale FE computation

Homogenization

Laws at macroscale for microscopic phenomena

(9)

Contents

1

Introduction

2

Overview of the thesis

Work environment

Workpackage 1: Development of a multiphase flow model

Workpackage 2: Development of a mechanical model

Workpackage 3: Coupled hydro-mechanical model

Workpackage 4: Reservoir modelling

Work plan

(10)

Work environment

Université de Liège

Université Joseph Fourier

University of Newcastle

(France, Grenoble) (Australia)

Geomechanics and Engineering research unit

Thesis supervised by F. Collin

Team Pr O. Buzzi

Expertise on coal

Laboratoire 3S-R

Thesis on FE²

by B. Van den Eijnden

Expertise in computational geomechanics

(FE code Lagamine)

(11)

Workpackage 1: Multiphase flow model

FE

2

method :

REV

Microscale FE computation

Constitutive equations

(flow law, storage law)

are applied only on the

microscopic scale.

Task 1.1

:

Extension of the FE

2

method

to unsaturated conditions.

Task 1.2

: Extension

to multiphase flow conditions (liquid and gas).

Task 1.3

: The developed

model is faced and compared with others

(12)

Workpackage 2: Development of a mechanical model

The

mechanical behaviour of the coalbed results from

the

geometry and the properties of the components.

Triaxial experimental results

REV responses

Task 2.1

: Evaluate numerically the

influence of the cleat density in the

REV on the macroscopic behaviour of the material.

Task 2.2

: Identification of the

material parameters through a

(13)

Workpackage 3: Coupled hydro-mechanical model

Task 3.1

:

Experimental campaign

Hydro-mechanical tests on an

Australian coal:

Shrinkage/swelling properties and permeability measurements

Task 3.2

:

Coupled model implemented in the FE code LAGAMINE.

Macroscale

REV

Microscale

(14)

Workpackage 4: Reservoir modelling

A synthetic reservoir model with

one production well is simulated

from the drilling of the well to the production period.

(15)

Work plan

1st year

2nd year

3rd year

4th year

(

)

: Multiphase flow model : Mechanical model : HM couplings : Reservoir modelling

: Literature review : Paper writing : Thesis writing

: Newcastle stay : Grenoble stay

(16)

Conclusion

High

potential for coalbed methane in Wallonia

Challenge = better understand methane migration to optimize recovery.

Development of a coupled hydro-mechanical model for coalbed methane

(17)

Thank you for your attention!

FE

2

approach for the modelling of coupled hydro-mechanical behaviour

of partially saturated coalbeds

Related work: Efficiency of shaft sealing for CO

2

sequestration in coal mines,

Presentation at the Workshop on Geomechanics & Energy EU 2015

(held from 13-10-2015 to 15-10-2015 in Celle, Germany).

(18)

References

Gu, F., Chalaturnyk, J., et al. (2005).

Analysis of coalbed methane production by reservoir and geomechanical

coupling simulation.

Journal of Canadian Petroleum Technology, 44(10).

Pan, Z. and Connell, L. D. (2012).

Modelling permeability for coal reservoirs: a review of analytical models

and testing data.

International Journal of Coal Geology, 92:1–44.

Piessens, K. and Dusar, M. (2006).

Feasibility of CO

2

sequestration in abandoned coal mines in belgium.

Geologica Belgica.

Shi, J.-Q., Pan, Z., and Durucan, S. (2014).

Analytical models for coal permeability changes during coalbed methane

recovery: Model comparison and performance evaluation.

(19)

SWOT Analysis

S W

O T

Strengths

Weaknesses

Opportunities

Threats

Positive

Negative

In

ter

na

l

E

x

ter

na

l

- Personal profile

- Work environment

- Strong modelling basis

- Clear objectives

- Experiments on coal required

to identify model parameters

- Innovative approach to model

coal behaviour

- Industrial interest

- High CBM potential in Wallonia

- Unfavorable political decision

about CBM ?

- No CBM production expertise

in Wallonia

(20)

Coalification

Carbon c

on

ten

t

W

a

ter c

on

ten

t

Gas content of coals

(21)

Global overview

Shale gas Tight gas Coalbed methane

Country CBM resources [1012m3] CBM annual production [109m3]

Russia 17.0 - 113.0 1

Canada 17.9 - 76.0 9

China 36.8 5

USA 21.5 52

(22)

Production

From Schlumberger (2009),

Coalbed Methane: Clean Energy for the World

Methane

Water

V

olume

Time

(23)

CBM versus Shale gas

Coalbed methane

Conventional

reservoir

Shale gas

Mines

Seal Source Reservoir Coal

Tight sand

gas

(24)

FE

2

1.Macroscopic structurediscretised by finite elements

3.REVassigned at each macroscopic IP

4. : apply appropriate

from the macroscopic deformation gradient tensor

Localization displacements to the REV

5. :

stress and deformation distributions in the REV

Microscale FE computation

6. : REV returned to the macroscopic IP

Homogenization averaged stress

7. Macroscopic internal nodal forces

2. c from the estimation

of the macroscopic nodal displacements relative to the external load

Macroscopic deformation gradient tensor omputed for each IP

8. Macroscopic stiffness matrix 9.Balancebetween external load and internal load?

Next time

increment evaluated

+

-Updated estimationof the nodaldisplacementsrequired (via macroscopic stiffness matrix)

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