Improved Application of Gas Reservoir Parameters

Improved Application of Gas Reservoir Parameters

ACARP Project C10008May 10th 2002

Mackay

Technology Transfer Update

GeoGAS

The Team.… Applicant Organisation - GeoGAS Systems Pty.

Ltd.Ray Williams, Eugene Yurakov

Supporting Organisations – CSIRO Energy Technology North Ryde

Abou Saghafi Multiphase Technologies Pty. Ltd.

David Casey James Cook University

Peter Crosdale $141,159 1 Year

Objectives

Improving the quality of input data in key areas.

Obtaining a clearer understanding of the combined

effects of sets of gas reservoir parameters.

Producing a set of sensitivity matrices that can be

used as an improved guide in modelling and in

identification of the most important data to acquire.

From the ACARP Submission

“……… the importance of considering the

gas implications is widely recognised.

What is not generally recognised, is the

variability in the gas reservoir and the

processes and limitations of the tools

available to undertake modelling

assessments.”

Parameter Sensitivity of results to parameter

Obtaining likelihood

Low Middle High Low Middle High Seam dimensions

Roadway dimensions Gas composition

Porosity Permeability

Langmuir isotherm Desorption time constant

Desorption pressure Reservoir temperature

Gas content Relative permeability

Pore pressure Compressibility

Matrix shrinkage Pore pressure

Transmissibility

From GeoGAS/CSIRO SIMED Procedure Manual 1998

For this project we look mainly at:

Gas sorption isotherms Use of multiphase testing to:

Validate gas sorption isotherms Generate relative permeability curves

Assess desorption time constant Gas drainage borehole recharge Other important stuff –

Permeability, porosity, compressibility Sensitivity analyses

An Example – The Isotherm Shock

0

2

4

6

8

10

12

14

16

18

20

0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000

Absolute Pressure (kPa)

Gas

adso

rbed (m

3/t)

GeoGAS 16.9% Ash

GeoGAS 13% Ash

CSIRO 12.1% Ash

CSIRO 8.9% Ash

CSIRO 12.8% Ash

58-36.xls

0

20

40

60

80

100

120

140

160

0 50 100 150 200 250 300

GeoGAS Isotherm

CSIRO Isotherm

Start of Comparisons

0

5

10

15

20

25

0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000


Gas

ad

sorb

ed (

m3/t

)

CSIRO

GeoGAS

JCU

0

5

10

15

20

25

0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000


Gas

ad

sorb

ed (

m3 /t

)

CSIRO

GeoGAS

JCU

Isotherm Comparison Tests – Factors Considered

Method – all essentially the same (gravimetric)

Grainsize distribution of tested coal Moisture before during and after

testing, including equilibrium moisture Consistency between distributed

samples

Methane Isotherm Comparison

0

2

4

6

8

10

12

14

16

18

20

0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000


Ga

s a

ds

orb

ed

(m

3 /t)

14.5% Ash, 2.3% Moisture GeoGAS

15.6% Ash, 2% Moisture JCU up to 5 kPa

15.5% Ash, 1.8% Moisture CSIRO

09

10

11

41

42

43


0

2

4

6

8

10

12

14

16

18

20

0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000


Ga

s a

ds

orb

ed

(m

3 /t)


9.2% Ash, 1.9% Moisture JCU up to 5 kPa

9% Ash, 1.9% Moisture CSIRO

09

10

11

41

42

43


0

2

4

6

8

10

12

14

16

18

20

0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000


Ga

s a

ds

orb

ed

(m

3 /t)




09

10

11

41

42

43


0

2

4

6

8

10

12

14

16

18

20

0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000


Ga

s a

ds

orb

ed

(m

3 /t)




09

10

11

41

42

43


0

2

4

6

8

10

12

14

16

18

20

0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000


Ga

s a

ds

orb

ed

(m

3 /t)



10% Ash, 3.4% Moisture CSIRO

09

10

11

41

42

43


0

2

4

6

8

10

12

14

16

18

20

0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000


Ga

s a

ds

orb

ed

(m

3 /t)

11% Ash, 3.8% Moisture GeoGAS



09

10

11

41

42

43

Density Comparisons of Sub Samples

Isotherms shown to be quite sensitive to density. A change of 0.1 g/cc results in around 6-18% change in sorption capacity. Replots by Crosdale

and Yurakov showed reduced scatter using the same density. Coal density inconsistencies identified as probably the most significant

contributor to isotherm differences.

Relative Densities (g/cc)

Adsorbed CH4 DensitiesCSIRO 0.415 g/cc

GeoGAS 0.6189 g/ccJCU 0.3196 g/cc

Laboratory 9 10 11 41 42 43 Average

GeoGAS 1.39 1.40 1.32 1.64 1.41 1.41 1.43

JCU 1.45 1.50 1.52 1.59 1.47 1.46 1.50

CSIRO 1.35 1.41 1.40 1.59 1.41 1.37 1.42

Grainsize Comparison

Particle size distribution @ "100 mm lens"

0

1

2

3

4

5

6

7

8

9

<0.

54

0.54

-0.6

5

0.65

-0.7

9

0.79

-0.9

5

0.95

-1.1

5

1.15

-1.3

9

1.39

-1.6

8

1.68

-2.0

4

2.04

-2.4

7

2.47

-2.9

9

2.99

-3.6

1

3.61

-4.3

7

4.37

-5.2

9

5.29

-6.4

6.4-

7.75

7.75

-9.3

8

9.38

-11.

35

11.3

5-13

.74

13.7

4-16

.63

16.6

3-20

.13

20.1

3-24

.36

24.3

6-29

.49

29.4

9-35

.69

35.6

9-43

.19

43.1

9-52

.28

52.2

8-63

.28

63.2

8-76

.59

76.5

9-92

.7

92.7

-112

.2

112.

2-13

5.8

135.

8-16

4.36

>16

4.36

Grain Size Bin (micron)

Siz

e D

istr

ibu

tio

n (

%)

CSIRO

Geogas

JCU

WYO109

WYO110

WYO111

NW0141

NW0412

NW1043

JCU Isotherm "As Received" and "Equilibrium Moisture" Assessment

0

2

4

6

8

10

12

0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000


Ga

s a

ds

orb

ed

(m

3 /t)



18.2% Ash, 2.1% Moisture JCU Eq.Mosture up to 5 kPa

18.2% Ash, 2.1% Moisture JCU Eq.Mosture up to 7 kPa

09

10

11

41

42

43

IsothermsField-Lab Desorption Pressure Comparisons

0

500

1000

1500

2000

2500

3000

3500

4000

0 1 2 3 4 5

Elapsed Time (hrs)

Bo

tto

mh

ole

Pre

ssu

re (

kPa

)

0

0.05

0.1

0.15

0.2

0.25

Wa

ter

& G

as

Pro

dcu

tio

n R

ate

(li

tre

s/m

in)

Stage 1 Stage 2 Stage 3

From Multiphase Technologies Pty. Ltd.David Casey

0

5

10

15

20

25

30

0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000


Gas

ad

sorb

ed (

m3 /t

)

Match Good?

1375 kPa - Lab Test

1241 kPa - Field

9.85 m3/t

GeoGAS

CSIRO

CH4 Grosvenor Desorption Pressure During Well Production

0

500

1000

1500

2000

2500

3000

0 5 10 15 20 25

Time (days)

Pre

ssu

re W

ater

Co

lum

n (

kPa)

GR#5

GR#4

GR#3

Comparison Desorption Pressures – Well, Multiphase, Laboratory

Methane Isotherm Goonyella Middle Seam Borehole GR01

0

5

10

15

20

25

30

0 500 1000 1500 2000 2500 3000 3500


Gas

ad

sorb

ed (

m3 /t

)

GRO0077, 13.4% AshGRO0074, 9.4% AshLab Test Desorption PressureMP Field Desorption PressureWell Desorption Pressure

0

2

4

6

8

10

12

14

0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000


Gas

ad

sorb

ed (

m3/t

)

11.2% Ash

10.7% Ash

Lab Test Desorption Pressure

Field Desorption Pressure

2058 kPa - Lab Test

2101 kPa - Field

8.71 m3/t

0

2

4

6

8

10

12

14

16

18

20

0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000


Gas

ad

sorb

ed (

m3 /t

)24.2% Ash

Lab Test Desorption Pressure

Field Desorption Pressure

746 kPa - Lab Test

451 kPa - Field

6.43 m3/t-800

-600

-400

-200

0

200

400

very

hig

h

high

mod

erat

e

mod

erat

e

mod

erat

e

low

low

low

very

low

very

low

Decreasing Permeablity -->

Fie

ld -

Lab

Des

orp

tio

n P

ress

ure

(kP

a)

DesP-Summary.xls

Idea is to back out relative permeability curves from history matching water and gas production

Have had difficulty doing this with SIMED in moderate to high permeability coal.

Same problem using EclipseCBM Have contracted Molopo (Wang Xingjin) to further SIMED curve matching

Matching per se is not the problem, it is getting a matchusing sensible parameters that is proving difficult……..

History Match for Cumulative Gas Production and Bottom Hole Pressure

0

5

10

15

20

25

30

35

40

45

50

0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00 4.50

Time (days)

Cu

mu

lati

ve

Ga

s P

rod

uc

tio

n (

Lit

re)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

wa

ter

Ra

te m

3/d

ay

) B

ott

om

Ho

leP

res

su

re (

10

00

Kp

a)

Simu. Cumu. Gas

Actual Cummulative Gas

Actual BHP

Simu. BHP

(Og34.dat)Fig. 2

Thickness: 2.22 mPi 1460 KpaPorosity 0-10.25 m 2% 10.25-17.78 m 1.2% > 17.78 m 1%Gas Content 7.9 m3/tVl=26.9 m3/t, Pl=2001 KpaPd=830 Kpa, Tau= 25 dayspermeability: 0-10.25 m 10 md 10.25-17.78m 2.5 md >17.78 0.55 md

History Match Profile

0

0

0

1

1

1

1

1

2

2

0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00 4.50

Time (days)

Cu

mu

lati

ve

Ga

s P

rod

uc

tio

n (

Lit

re)

Simu. Water

Actual Water Production

(Og34.dat)

The water rate in the input data file was set as actual data

Fig. 1

Thickness: 2.22 mPi 1460 KpaPorosity 0-10.25 m 2% 10.25-17.78 m 1.2% > 17.78 m 1%Gas Content 7.9 m3/tVl=26.9 m3/t, Pl=2001 KpaPd=830 Kpa, Tau= 25 dayspermeability: 0-10.25 m 10 md 10.25-17.78m 2.5 md >17.78 0.55 md

History Matched Relative Permeabi l i ty

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 0.2 0.4 0.6 0.8 1

Water Saturation

Rel

ativ

e P

erm

eab

ilit

y

Fi g. 3

Gas

Water

Parameters varied are:- porosity- permeability- sorption time constant- relative permeability

What is tau? Supposedly, the time taken for 63.2% of gas to

desorb from a slow desorption gas content test

Where = desorption time constant

= coal matrix shape factor

D = diffusion coefficient

DteQ

Q

10

632.0110

eQ

Q

D 1

But is it 63.2% of Qm, Q1+Q2 or just Q2? We have related tau (from Qm) to IDR30.

y = 4.243800x-0.349979

R2 = 0.457498

0

2

4

6

8

10

12

14

16

18

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0

IDR30

Tau

Assessed the variability

For a particular study area, define a range of tau’s applicable to the gas content magnitude for that deposit for use in sensitivity assessments

y = -0.349979x + 1.445459

R2 = 0.457498

0

0.5

1

1.5

2

2.5

3

3.5

4

-4 -3 -2 -1 0 1 2

Ln IDR30

Ln

Tau

Qm mean Tau hi Tau mean Tau low3.36 23.8 9.5 3.8

4.58 18.7 7.5 3.06.81 13.5 5.4 2.2

8.50 10.7 4.3 1.79.47 9.2 3.7 1.510.01 8.3 3.3 1.310.38 7.7 3.1 1.210.63 7.2 2.9 1.2

10.83 6.9 2.7 1.1

At low perm (1mD, almost no difference between tau 4.5 and tau 30 days (8.5 m3/t)

MG Drainage Options

B HdgA Hdg

0

1

2

3

4

5

6

7

8

9

200 225 250 275 300 325 350 375 400 425 450 475 500

Distance From MG (m)

Gas

Co

nte

nt

(m³/

t)

1 mD 1 mD tau 30 days Gas Content Assistance Line Initial Gas Content Lateral Distance

20 days on line 100 md tau 4.5

Lateral Distance 15 m from B Hdg Qm Line @ 4 m3/t

640 days on line 1 md tau 4.5 days

640 days on line 1 md tau 30 days

Perm.xls{Change in Gas Content}

20 days on line 100 md tau 30

At high perm (100 mD, big difference between tau 4.5 and tau 30 days (8.5 m3/t)

MG Drainage Options

B HdgA Hdg

0

1

2

3

4

5

6

7

8

9

200 225 250 275 300 325 350 375 400 425 450 475 500

Distance From MG (m)

Gas

Co

nte

nt

(m³/

t)

100 mD tau 30 Gas Content Assistance Line Initial Gas Content Lateral Distance 100mD tau 4.5 days

20 days on line 100 md tau 4.5

Lateral Distance 15 m from B Hdg Qm Line @ 4 m3/t

640 days on line 1 md tau 4.5 days

640 days on line 1 md tau 30 days

Perm.xls{Change in Gas Content}

20 days on line 100 md tau 30

Gas drainage efficiency diminishesGas drainage efficiency diminishestoward the end of boreholes,toward the end of boreholes,Not from the end…Not from the end…

0

2

4

6

8

10

200 250 300 350 400 450 500

Distance from previous maingate (m)

Gas

con

tent

(m

3/t)

25 m spacing, 95 days drainage

50 m spacing, 240 days drainage

100 m spacing, 720 m drainage

Line of "barrier"10 m off B Hdg

Initial gas content

Cross panel borehole A Hdg B Hdg

Effective end of borehole 30 moff B Hdg rib

A H

eadin

g

B H

eadin

g

Lin

e o

f barr

ier

EffectEffectOf HoleOf HoleSpacingSpacing

0

2

4

6

8

10

200 250 300 350 400 450 500

Distance from previous maingate (m)

Gas

con

tent

(m

3/t)

Permeability 10 mD in X& 2 mD in Y directions

Permeability 10 mD in X& 10 mD in Y directions

Permeability 2 mD in X &10 mD in Y directions

Line of "barrier"10 m off B Hdg

Initial gas content

Cross panel borehole A Hdg B Hdg

Effective end of borehole 30 moff B Hdg rib

A H

eadin

g

B H

eadin

g

Lin

e o

f barr

ier

Effect OfEffect OfDirectionalDirectionalPermeabilityPermeability

xx

yy

A H

eadin

g

B H

eadin

g

Lin

e o

f barr

ier

Effect OfEffect OfPorosityPorosity

xx

yy

MG Drainage Options

B HdgA Hdg

0

1

2

3

4

5

6

7

8

9

200 225 250 275 300 325 350 375 400 425 450 475 500

Distance From MG (m)G

as C

on

ten

t (m

³/t)

1% 2% 3% Gas Content Assistance Line Initial Gas Content Lateral Distance

150 Days on LineLateral Distance 15 m from B Hdg Qm Line @ 4 m3/t 150 Days on Line 150 Days on Line

Poro.xls{Change in Gas Content}

Conclusions Hope to bring project to a close in next couple of months Scope to improve understanding and standardisation

between labs on isotherm testing. Need to evaluate combinations of parameters eg as we

did for ranges of tau at low and high permeabilities. A wider range of field measurements is important to lock

down parameters. Eg measurement of both water and gas flow from in-seam boreholes greatly improves the robustness of the modelling.

The bottom line is to create more robust modelling that is relevant. That means:- better input data- good modelling packages. - defining the approach to modelling that includes being critical every inch of the way, quantifying uncertainty……..

Improved Application of Gas Reservoir Parameters

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