Hcmut Training-2 Cbm

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CHONNAM NATIONALCHONNAM NATIONALUNIVERSITYUNIVERSITY

Coal Bed MethaneCoal Bed Methane as aas a

Future Energy ResourceFuture Energy Resource

DEPT. OF ENERGY & RESOURCES ENG.DEPT. OF ENERGY & RESOURCES ENG.

CHONNAM NATIONAL UNIVERSITYCHONNAM NATIONAL UNIVERSITY

17 Feb. 2012 (Fri.)17 Feb. 2012 (Fri.)

Lectured byLectured by JeonghwanJeonghwanLee, Prof.Lee, Prof.


1)1) Coal Bed Methane Play ConceptsCoal Bed Methane Play Concepts--The BasicsThe Basics

2)2) UncertaintyUncertainty--What We Need to AssessWhat We Need to Assess

3)3) Addressing Uncertainty And Estimation of GIIPAddressing Uncertainty And Estimation of GIIP

4)4) Exploration StrategiesExploration Strategies

5)5) Reservoir EngineeringReservoir Engineering --Pitfalls and ConsiderationsPitfalls and Considerations

6)6) Economics and EnvironmentEconomics and Environment

7)7) CBM Project inCBM Project in NalaikhNalaikh Coal Mine, MongoliaCoal Mine, Mongolia

ContentsContents


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Chapter 1Chapter 1

Coal Bed Methane Play ConceptsCoal Bed Methane Play Concepts

The Basics



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CBM refers to methane adsorbed

into the solid matrix of coal, it is

sometimes referred to as coalseam gas (CGS).

Predominantly methane (CH4)- tasteless, odorless, colorless, non-toxic gas

It is the simplest alkane

compounds and the primary

constituent of natural gas.

Compared to conventional natural

gas, CBM has relatively fewimpurities, predominantly CO2.

CBM is released from coal with a

reduction in production via

dewatering.

What is CBM ?What is CBM ?What is CBM ?


Characteristics of CBM

Natural gas trapped into reservoir of coal bed

Classified to unconventional natural gas

Various gas mixture of Methane, Carbon dioxide, Nitrogen etc

95% of Methane and 1,000 Btu/ft of Calorific value

1,069

973

1,039

1,058

1,0241,068

Btu/scf

0.01

-

-

-

--

H2

0.17

0.20

0.24

0.10

0.15-

1.40

0.29

0.01

0.01

0.014.90

96.87

90.75

97.32

99.22

96.0594.40

Cent-appalachian

N. Appalachian

Arcoma

Warrior--

Pocahontas No.3

Pittsburgh

Kittanning

Lower Hartshorne

Mary LeeNatural Gas

O2C2+CH4BasinSource


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Process of CBM util ization

Drill Dewatered Extracted Piped Compressed Market


Usages of CBM

As a gaseous fuel, it can be used for various usages

Micro Gas Turbine, Gas Engine, Fuel Cells

Combined Heat & Power GenerationFuel for Power

Generation

City Gas

Boiler, Space HeatingHeating Source

Methanol, DME

Diesel, gasolineChemical

Source

One of the important Energy Source


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CBM Gas Reservoir


To produce methane from coal beds,

water must be drawn off first, lowering

the pressure so methane can flow out

of the coal and to the well bore. To extract the gas, a steel-encased hole

is dri lled into the coal seam (1001500

meters below ground)

As the pressure within the coal seam

declines due to natural production or

the pumping of water from the coalbed,

both gas and 'produced water' come to

the surface through tubing

Then the gas is sent to a compressor

station and into natural gas pipelines

CBM Extraction

Production scheme of gas and water for

a typical coal-bed methane well.


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- The evolution of coal is generally broken into two phases: peatificationpeatification and coalificationcoalification .

- During coalification, large quantities of methane-rich gas are generated and stored within the coal

on internal surfaces


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CBM Storage Mechanism


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Gas Storage Mechanism

Equil. sorption (p dependent)

Non-equil sorption (p & t dependent)

Sorption time: Time required for 63% of total

sorbed gas to be released. It indicates how

rapidly gas will be desorbed. It affects initial

gas production rate.

Two Approaches for Sorption Isotherm:

gPEVrV

tV

1

gPLP

gPLV

gPEV

Equilibrium desorption

Non-equilibrium desorption


Adsorption capacity of coal is defined as the volume

of gas adsorbed per unit mass of coal

The capacity to adsorb depends on the rank andquality of coal.

Most of the gas in coal beds is in the adsorbed form.

When the reservoir is put into production, water in

the fracture spaces is pumped off first. This leads to

a reduction of pressure enhancing desorption of gas

from the matrix.

Adsorption Capacity


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CBM Transport Mechanism


Permeability is key factor for CBM

Coal itself is a low permeability

reservoir

(The permeability of the coal matrix isnegligible by comparison)

Almost all the permeabil ity o f a coal

bed is usually considered to be due to

fractures

Fractures in coal are in the form of

cleats and joints

Joints are larger fractures through the

coal that may cross lithological

boundaries. Coal cleats are of two types: butt c leats

and face cleats

Permeability of CBM Reservoirs

are non-continuous and

end at face cleats

are continuous and

provide paths of higher

permeability


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CBM has dual-porosity system.

- Dual-porosity nature: macropore and micropore

The porosity of coal bed reservoirs is usually

very small, ranging from 0.1 to 10%.

CBM reservoirs are mostly shallow as the coal

matrix does not have the strength to maintain

porosity under the pressure of signif icant

overburden thickness.

Porosity of CBM Reservoirs


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DUAL-POROSITY SYSTEM IN COAL

MATRIX BLOCKS CONTAINING MICROPORES

Butt Cleat

FaceCleat

Dual-porosity nature: macropore and micropore

The natural f racture network (macropore):

Uniformly dis tributed and composed of face and butt

cleat [10-3 cm] which are orthogonal to each other.

The face cleat is continuous throughout the reservoir

and capable of draining large areas.

The butt cleat is discontinuous and ends at the face

cleat.

Thus, the anisotropic permeabilit y nature.

Permeability in the direction o f face cleat is

considerably larger than that in the direction of butt

cleat.

The matrix (micropore):

Existing between the natural fracture network. Its pore size is 5-10 angstrom[10-8 cm].

It is assumed that openings are not accessible to

water and they contribu te major portion of gas

storage areas.



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NG Reserves: 179.53 X 1012m3

Coal Reserves: about 25 Trillion tons

CBM reserves:166~692 X 1012m3

130 ~550 billion tons -equivalent to LNG

North America: 27~125 TCM

South & Central America: 0.4~0.9 TCM

Europe: 4.6~7.7 TCM

Former Soviet Union: 114~460 TCM

Af rica: 0.8~1.6 TCM

As ia Pacif ic : 18~96 TCM

Estimation of World-wide CBM ReservesEstimation of WorldEstimation of World --widewide CBM ReservesCBM Reserves


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Coal Reserves: 3.8 Trillion tons

CBM Reserves: 400 TCF(8.8 billion tons - equivalent to LNG)

CBM Production

1994: 0.86 TCF (5% of gas consumption for home use in US)

2004: 1.75 TCF (9% of gas production in US)

Sanjuanbasin and Warrior basin are the largest CBM production area

CBM Development in USCBM Development in USCBM Development in US


26

CBM Production of Arkoma in US


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CBM Reserves: 1060~2800 TCF(23~61 Billion tons equivalent to LNG)

CBM Development

1996:(established CUCBM)

Puxin, Lianingand Jincheng, Shanxi are widely developed

CBM of 1.15 BCM is commercially used in China

CBM Development in ChinaCBM Development in ChinaCBM Development in China


28Liaoning, Fuxin basin

CBM Production in Shanxi and Liaoning

Shanxi, Hedong basin


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Fuel for electric power (micro gas turbine, compact gas engine, steam supply and powergeneration)

Fuel for CNG vehicle / heat supply (city gas, heating)

Chemical material (methanol, DME) / Transportation by LNG Liquefaction

CBM Utilization Shanxi(Jinsheng)CBM UtilizationCBM Utilization Shanxi(JinshengShanxi(Jinsheng))



CBM Reserves: 0.23 Billion tons (equivalent to LNG)- based on the 2P

CBM Production

2008: 2.93 Million tons /year, 7,542 tons/day(equivalent to LNG)

LNG Plant construction plan of 8.80 Million tons scale is ongoing now in Gladstone

and Queensland Curtis etc.

CBM Development in AustraliaCBM Development in AustraliaCBM Development in Australia

Scale of gas market in eastern Austrilia is about 12 million tons/year

CBM : 25% supply of gas demand in eastern Australia


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Overseas CBM Business of Korea (KOGAS)Overseas CBM Business of Korea (KOGAS)Overseas CBM Business of Korea (KOGAS)

Blue Energy and GLNG Investmentfor CBM BusinessR&D Business for Green Energy in Mongolia


Chapter 2Chapter 2

UncertaintyUncertainty

What We Need to KnowWhat We Need to Know


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CBM EvaluationCBM EvaluationCBM Evaluation



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Measurement of Gas Content

Volumetric Displacement Technique

The desorbed gas that collects in a canister is periodically released into

volumetric displacement apparatus and measured as a function of time,

temperature, and pressure (Q vs. p at T).

Desor

ption

Adsor

ption

Sorption isotherm curve can be incorporated

by Langmuirs sorption theory

Langmuir sorption

gPLP

gPLV

gPEV

LANGUMUIR SORPTION ISOTHERM

VE:Amount of gas adsorbed at PgVL : Volume constant (maximum amount

of gas that can be adsorbed on solid

surface)

Maximum adsorptive capacity; the upper

limit of adsorption as pressure

approaches infini ty

PL: Pressure constant (ratio of desorption

and adsorption rate constant) Pressure

at which adsorbed gas is one-half the

maximum; VL /2


Example calculation

cfscfpp

pVV

psiap

psiapcfscfV

Lg

g

LE

L

g

L

/29.4)0.571()100(

)100()8.28(

0.571

100/8.28


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Measurement of Gas Content



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Chapter 3Chapter 3

Addressing Uncertainty AndAddressing Uncertainty And

Estimation of GIIPEstimation of GIIP


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Mining activity: The initial CBM potential of an area is almost exclusively

based on historic or ongoing regional mining activity.Field mapping: Fly-over, work-over survey, and literature based on

mapping of the research permit area allow good overview

of the structure and stratigraphy.

Seismic survey: Not commonly acquired to specifically target shallow

coals.

Drilling and logging: Quantitative data acquisition really commences with thedrilling of wells-petrophysical log analysis

Coring: To Sample the coals directly for gas content.

Procedure to address uncertaintyProcedure to address uncertaintyProcedure to address uncertainty



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Chapter 4Chapter 4

Exploration StrategiesExploration Strategies

Flexibil ity, Commitment andFlexibil ity, Commitment and

FitFit--forfor--PurposePurpose


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Chapter 5Chapter 5

Reservoir EngineeringReservoir Engineering

Pitfalls and ConsiderationsPitfalls and Considerations


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Volume

Time

Gas

Water

Idealized conventional gas production

Volume

Time

GasWater

Idealized coalbed methane product ion

Dewatering

Stage

Stable

Production

Stage

Decline

Stage

Production - Gas


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In a coal-bed methane well, water is produced in large

volumes, especially in the early stages of production;

as the amount of water in the coal decreases, gas

production increases.

Require estimates on water. Total water in-place, and

likely re-injection target formations

- i.e. Wyoming River basin 70 MMbbl water a month (18,000 wells)

Disposal is commonly via 4 processes:

- Surface discharge- Evaporation ponds

- Re-injection of produced water

- Injection of salt water slurry fol lowing reverse osmosis process

The Concerns of Produced water


Well completion Welhead

PRODUCTION WELL


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Chapter 6Chapter 6

Economics and EnvironmentalEconomics and Environmental

ConsiderationsConsiderations



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License Issues

China

- Coal Mining and CBM are different License

- Coal Mining License to be given by Local Government

- CBM License to be given by Central Government

(Same to Oil & Gas Legal System)

Australia

- Coal Mining and CBM may be different License

- Rights of CBM license is same to those of Oil & Gas

India

- CBM Legal system is same to Oil & Gas Law

USA

- Different System as per each state


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Productionofcoalbed methaneisaccompaniedby

significantenvironmentalchallenges,including

prevention

of

unintended

loss

of

methane

to

theatmosphereduringundergroundmining,and

disposaloflargequantitiesofwater,sometimes

saline,thatareunavoidablyproducedwiththegas.

Methanefromcoalbed reservoirscanberecovered

economically,butdisposalofwaterisan

environmental

concern.

Environmental Challenges


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Thank You !Thank You !

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Hcmut Training-2 Cbm