Gas Content Procedure

8/12/2019 Gas Content Procedure

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tgi

!! Coalbed Gas Content: InsightsCoalbed Gas Content: Insights

Presented to:

Mid-Continent Coalbed Methane ForumTulsa, OK

June 13, 2002

Tim Pratt, TICORA720/[email protected]

a subsidiary of GTI


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tgia subsidiary of GTI

Coalbed Reservoir Gas Content

Gas Storage Mechanisms:

Free gas within natural fractures. Dissolved gas in water within natural fractures. Adsorbed gas within the coal matrix.

Total GasVolume

Free GasVolume

DissolvedGas Volume

AdsorbedGas Volume+ +=

Typically > 95%


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Long Term Desorption: Best PracticeAnalysis Protocols

450

400

350

300

250

200

150

100

50

0

-50

-100

-150

-200

-250

G a s

o n

t e t , ( S C / T o ,

i r - D r

)

0.0 0.5 1.0 1.5 2.0 2.5 3.0 40.0 40.5

Square Root Elapsed Time, ( Hours)

Lost Gas

Measured Gas

Lost GasTime

Residual Gas

Long Term DesorptionExperiment Terminated.

Sample Crushed

to -60 Mesh.

Gas Composition Analysis

ResidualGas

Analysis

LostGas

Analysis


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Coal Flow Mechanisms

Wellbore

InducedFracture

Macro-PorosityFracture Porosity

> 50 nmMeso-Porosity> 2 nm < 50 nm

Micro-Porosity

< 2 nm

Sorption Diffusion Darcy Flow Pipe Flow


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Gas Sorption Knowledge Its a Good Thing

0

100

200

300

400

500

600

700

800

900

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

Moisture + Ash Content, wt. fraction

I n - S i t u

G a s

C o n

t e n t , s c

f / t o n

Maximum gas content (0% moisture + ash): 837 scf/ton

Gas content is 0 scf/ton at 0.9663 moisture + ash

Maximum gas content (0% moisture + ash): 837 scf/ton

Gas content is 0 scf/ton at 0.9663 moisture + ash

R2 = 0.9663


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Gas Sorption Knowledge Its a Good Thing

D r y ,

A s h - F r e e

G a s

C o n

t e n t ,

s c

f / t o n

Depth, ft

Single Rapid Gas

Average LongTerm Desorption


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Gas Resource - What We Get From Core

Coalbed Gas ReservoirsEvaluate:

In-situ Gas Content & Bulk Density % Gas Saturation Gas Composition

Reservoir Pressure & Temperature Reservoir Volume (Area & Thickness)

Coalbed Gas ReservoirsEvaluate:

In-situ Gas Content & Bulk Density % Gas Saturation Gas Composition

Reservoir Pressure & Temperature Reservoir Volume (Area & Thickness )


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Data Confidence

UNCERTAINTY DRAINAGEAREA

THICKNESS IN-SITUDENSITY

IN-SITU GASCONTENT

HIGH

MEDIUM

LOW

Commonly Used Protocols

Very High Sampling Density

Best Practice Protocols

GIP = A h c G c


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500

300

200

100

0

400

0 500 1,000 1,500 2,000

Pressure (psia)

M e

t h a n e

S t o r a g e

C a p a c

i t y

( s c

f / t o n

)

Methane Storage Capacity450 scf/ton

Initial Reservoir Pressure

1,620 psia

InitialGas

Content355 scf/ton

Typical Methane Isotherm

Critical Desorption Pressure632 psia

Abandonment Gas Content125 scf/ton

Abandonment Pressure100 psia

Gas Recovery Factor (230/355) X 100 = 64.8% scf/ton

230 scf/ton


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Coal Gas Analyses Flow Chart(Minimum Data Requirements)

FIEL D L A B ORA TORY ANALYSIS

SampleAcquisition

FieldDesorption(short -term)

Desorption(long-term)

Desorption Data Entry,Lost Gas Analysis,

Data Analysis

Final Analysis

Lab Testing

Sample Preparation

PreliminaryData &Field

Report

Data

Integration

Residual Gas

Density

Sorption IsothermPetrographyChemistry

Initial ProjectReview/Design

With Client

Well Site

Transport

to Lab

Sample

Submission

RapidGasSM

Final Project

Report

Client Follow-up

DataInterpretation

SampleAcquisition

FieldDesorption

(short -term)Desorption(long-term)

Desorption Data Entry,Lost Gas Analysis,

Data Analysis

Final Analysis

Lab Testing

Sample Preparation

PreliminaryData &Field

Report

DataIntegration

Residual GasMoisture Holding Capacity

Density

Sorption IsothermPetrography

Chemistry

Initial ProjectReview/Design

With Client

Well Site

Transport

to Lab

Sample

Submission

RapidGasRapidGasSMSM Log Processing

Final Project

Report

Client Follow - up

Data


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How Long Does The Job Last?

That depends on the coal desorptionproperties and the extent of the analysis

program.

That depends on the coal desorptionproperties and the extent of the analysis

program.

Job A

Job Z

L a

b

A n a

l y s

i s

Months: 1 2 3 4 5 6 7 8 9 10 11 12

Job A

Job Z

Function of desorptioncharacteristics

D e s o r p

t i o n

A n a

l y s

i s

Function of TICORA efficiency &third- party vendors

RapidGas SM


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Gas Mobility ( Movement Characteristics)

S o r p

t i o n

T i m e

s l o w

f a s t

Ligni te Subbi tuminous C B A

High Vol.

B i t u m i n o u s C B A

Medium Vol .

Bi tuminous

P R B

S J B


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Residual Gas vs. Crushed Gas vs. RapidGas RapidGas RapidGas RapidGas SM

Time

RapidGas SM

F a s t

S l o w

D e s o r

b e

d G a s

V o

l u m e

Time

Residual Gas

F a s t

D e s o r p t i o n

S l o w D e so r p t i o n

residualg as

residualg as

Time

Crushed Gas

F a s t

S l o w

crushedg as

c rushedg as


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Long Term Desorption: Best PracticeAnalysis Protocols

450

400

350

300

250

200

150

100

50

0

-50

-100

-150

-200

-250

G a s

o n

t e t , ( S C / T o ,

i r - D r

)

0.0 0.5 1.0 1.5 2.0 2.5 3.0 40.0 40.5

Square Root Elapsed Time, ( Hours)

Lost Gas

Measured Gas

Lost GasTime

Residual Gas

Long Term DesorptionExperiment Terminated.

Sample Crushed

to -60 Mesh.

Gas Composition Analysis

ResidualGas

Analysis

LostGas

Analysis


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Sorbed Phase Gas Composition

Twenty Mile #21C-3523

89.27 90.37 88.77

61.47

8.53 7.73 8.29 8.992.18 1.82 2.92

29.52

0

20

40

60

80

100

Uppe r Inte rval,Preserved

Middle Inte rva l,Preserved

Lowe r Inte rval,Preserved

Low e r Inte rva l,Non-Preserved

M o

l e %

CH4

CO2

N2


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Natural Fracture Development(Tectonic)

vs. Rank

H a r d g r o v e

G r i n

d a

b i l i t y

I n d e x

( F r a c

t u r e

D e v e

l o p m e n

t )

Coal Rank

High Volatile

A Bituminouus

Generalized Graphic


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X-Ray Radiograph Gray Level (0 - 255)Density Profile

0 50 100 150 200 250

Coal Gas Reservoir Systems


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Sorption Isotherm Parameters

S o r b e

d V o l u

m e

Pressure P P

Temperature Moisture Gas Sorbate

SAME COALSAME COAL

N2

CH4

CO2

C2 +


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tgi a subsidiary of GTI

Storage Capacity Versus Moisture Content

S t o r a g e C

a p a c

i t y

( S o r b e

d G a s

V o

l u m e

)

Pressure

1-2% moisture

10% moisture

15% moisture

20% moisture

27% moisture

= 30% moisture


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Sorption Isotherm Parameters

S o r b e

d V o l u

m e

Pressure P P

Mineral MatterConcentration Vitrinite

ConcentrationOxidation

SAME RESERVOIRSAME RESERVOIR


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The Analytical Goal is to ConstructComprehensive and Critical Information...

Isotherm Comparison& Gas Recovery Parameters

0

50

100

150

200

250

300

350

400

0 250 500 750 1,000 1,250 1,500 1,750 2,000

Pressure, psia

I n - S

i t u

S t o r a g e

C a p a c

i t y ,

s c

f / t o n

Methane

Gas Mixture - Binary

In-Situ Gas Content

Binary Storage Capacity: 262 scf/ton(Modeled Sorbed Gas Composition: 86.1% CH4 ; 13.9 % CO2)In-Situ Gas Content: 234.12 scf/tonReservoir Pressure: 1461.3 psiaCritical Desorption Pressure: 1,069.4 psiaGas Recovery Factor (fraction, assumes abandonment pressure of 40 psia): 0.91

Binary Storage Capacity: 262 scf/ton(Modeled Sorbed Gas Composition: 86.1% CH4 ; 13.9 % CO2)In-Situ Gas Content: 234.12 scf/tonReservoir Pressure: 1461.3 psiaCritical Desorption Pressure: 1,069.4 psiaGas Recovery Factor (fraction, assumes abandonment pressure of 40 psia): 0.91


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Reservoir Thickness - Inorganic Dilution

G a s

C o n

t e n

t

1.30 1.75 2.45

COAL CARB SHALE

~0% ash ~50% ash ~100% ash

Density g/cm 3


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Gas Content Versus Coal Composition

Uintay = -7.3705x + 697.24

R 2 = 0.9502

Piceancey = -4.5427x + 415.99

R 2 = 0.8316

San Juany = -5.6368x + 532.64

R2 = 0.9196

0

100

200

300

400

500

600

700

800

0 10 20 30 40 50 60 70 80 90 100

Moisture + Ash (weight %)

I n - S i

t u G a s

C o n

t e n t ( s c

f / t o n

)UintaPiceanceSan Juan

Rule-of-thumb upper density limit: 1.75 g/cm 3


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Creating Value withGas Sorption Knowledge! Exploration

! Is the Resource Present go/no go! Producibility Economic Viability (when should the gas come)! Critical Reservoir Properties Gas Mobility

! Asset Valuation! Resource In Place! Recovery Factor Producible Reserves! Resource Quality Sorbed Phase Gas Composition

! Asset Development! Optimum Flowing Pressure Critical Desorption Pressure! Gas Processing Gas Quality! Infield Development Potential

Assumption is that the data is collected, analyzedand reported using best practices protocols

Assumption is that the data is collected, analyzedand reported using best practices protocols

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Gas Content Procedure

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