Moranbah North Coal Seam Gas Development – Technical and Statutory · 2008-02-06 · 1 GeoGAS Moranbah North Coal Seam Gas Development – Technical and Statutory Anglo Coal Australia

1

GeoGAS

Moranbah North Coal Seam Gas Development – Technical and

Statutory

Anglo Coal Australia Pty. Ltd./GeoGAS Pty. Ltd.ACARP Gas and Outburst Workshop

Mackay 29th June 2007

Hugh Luckhurst-Smith, Anglo Coal Australia Pty. Ltd.Ray Williams, GeoGAS Pty. Ltd.

GeoGAS

To Cover

Statutory and Legal (Hugh Luckhurst-Smith)Technical (Ray Williams)

2

GeoGAS

Queensland recent Statutory history.Coal Mine Health & Safety Act & Regulations 2000Petroleum & Gas Act & Regulations 2004“Surface activities related to [petroleum &] gas activities’

Regulations

GeoGAS

ACA History

Moura-> Dawson opencut mine: PL94/ATPs acquisition 2006Grasstree U/G mine: 32MW Power station 2006Moranbah North U/G mine:Gas sales 2006/Power station 2008

U/G mines; gas drainage for ‘mineability & greenhouse

3

GeoGAS

Petroleum & Gas Act target compliance

Moranbah North 1st quarter 2007Dawsonlate 2007Grasstree mid 2008

GeoGAS

Legal Aspects.

Operational: Separate SSMs-Underground; Surface Coal; Surface Gas; Power StationDrilling: Each rig has own SSM. Clear signage & separation eg valve or flange.Where jurisdictions overlapCMHSA always takes precedence!

4

GeoGAS

Compliance issues.AS4801: Corporate overview complianceACA solution: Parallel HSEMSs

Recommendations1.Adopt as many as possible of existing mine procedures2. Conduct joint Risk Assessments3. Audits, inspections to be based on SafeOP-a good tool!

GeoGAS

Introduction

Statutory and Legal (Hugh Luckhurst-Smith)Technical (Ray Williams)

Objectives to Produce gas at the required rateAs uniformly and as long as possibleAt minimum cost (maximum spacing/drainage times)Meeting requirements for mine gas management as the priority

For this presentation:To demonstrate the forecasting processTo highlight issues related to meeting the twin needs of mine gas emission control and gas utilisation.To comment on risk and uncertainty

5

GeoGAS

Outline of Forecasting Process

Mine Plan Mine Schedule

Assign Gas Drainage Boreholes

Geology and Gas Reservoir Properties

Predrainage Models

Empirical Data, History

Define Reservoir Regions

Model Flow Curves forEach Region

Predrainage Borehole Spacing

Test Time Available Remaining Gas Content Uniformity of gas production

Longwall Ventilation Capacity

Longwall emission

modelling

Sum Gas Production from Various Sources

Longwall Model

Calibration

Assess Uncertainty

Well Schedule/Sequencing

GeoGAS

Gas Reservoir

6

GeoGAS

Gas Content

0 100 200 300 400 500

Depth (m)

Mea

sure

d G

as C

onte

nt @

15%

Ash

(m3/

t)

GM SeamGL SeamP Seam & splitsQA/QB SeamsLinear (GM Seam)

MNCGasContentMasterAug2006.xls{Main(2)}

GeoGAS

Gas Sorption Isotherms

0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000

Pressure (kPa, abs)

Gas

Ads

orbe

d (m

3 /t, r

es te

mp)

MN0035 33°C MN0037 33°C WB1-04 40.9°CNM1-11 43.5°C NM1-10 43.5°C NM1-10 43.5°C

IsothermsMNCDec06.xls{GM}

Ash 17.5%, Reservoir

Temperature 33.0°C

7

GeoGAS

Permeability

0 50 100 150 200 250 300 350 400 450 500

Depth of Cover (m)

Perm

eabi

lity

(mD)

{log

sca

le}

GM Low Perm Domain

GM Seam High Perm DomainGL Seam

P Seam - High Perm DomainGU, Q, P Seam Low Perm Domain

Perm domain boundaryGL seam assumed Permeability

MNC_Permeability.xls {AllPermSorted}

Low Perm Domain

High Perm Domain

GeoGAS

Effect of Stress

12 fold reduction in permeability for every Mpaincrease in stress

0.1

1

10

100

10000 500 1000 1500 2000 2500 3000

Effective Stress (kPa)

Perm

eabi

lity

(mD

)

8

GeoGAS

Gas Saturation

As important as permeability to gas deliverability

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

18.0

20.0

0 250 500 750 1000 1250 1500 1750 2000 2250 2500

Absolute Pressure (kPa)

Gas

Abs

orbe

d (m

3 /t)

saturation.xls{Sheet1}

Gas desorption pressure

Original reservoir pressure

A

B

Gas saturation = A / B %

GeoGAS

Comparing Different Gas Saturations

0

2

4

6

8

10

12

14

16

18

0 1000 2000 3000 4000 5000Absolute Pressure (kPa)

Gas

Ads

orbe

d (m

3/t)

ExampleIsotherm.xls

Critical gas desorption pressure = 1999 kPaa

Gas saturation= 81%

Gas saturation= 75%

Gas saturation= 70%

Even though gas content and permeability might be the same, changes in gas saturationhave an enormous effect on gas production, gas content reduction and how the well will operate.

Getting gas out is all about reducing pressurethroughout the reservoir.Gas sat of 70% may notseem too different from80%, but the additionalimpost on pressurereduction is enormous.

Then there is also the effect on permeability of increasing effective stress

9

GeoGAS

Predrainage Gas

GeoGAS

Underground In-Seam (UIS) Flow Curves

Basic curve defined empirically.

Application to each riser is based:• Material balance• Adjustment flow to account for actual metres drilled• A flow factor producing 70~80% recovery with 1~2 m3/t remaining gas content.

0 50 100 150 200 250 300 350 400 450 500

Time on Line (days)

Gas

Flo

w (l

/m/m

in)

Gas

Rec

over

y

107-36a107-31a/b107-16107-23MG108-3Average

Moranbah THE CHART 20-9-06RW.xls{107-

10

GeoGAS

UIS Gas Total

Gas flows summed according to drilling schedule

Nov-06 Nov-07 Nov-08 Nov-09 Nov-10 Nov-11 Nov-12 Nov-13 Nov-14 Nov-15

Gas

Pro

duct

ion

(TJ/

day)

UIS risers

RegionProduction.xls{WellConstants}

GeoGAS

Surface to In-Seam (SIS) Drilling

Modelling uses SIMED II Models calibrated on SIS wells INGM001~3 to fix the not so easily measured parameters (compressibility, porosity, relperm, n factor, skin).Model includes reduction in perm with increasing effective stress (n factor) and matrix shrinkage. Utilises experience from MGP.

11

GeoGAS

Reservoir Regions

Concept of “reservoir regions” is applied to model the continuum of changing reservoir parameters with depth of cover.Parameters within each region are assumed constant – only for the purpose of managing the modelling.Applied to GM and P seams

GeoGAS

GM Seam Reservoir Regions

Before Mining

Mining Affected

Reg

ion

Are

a (k

m2)

Dep

th (m

)

Mea

sure

d G

as C

onte

nt a

t Se

am A

sh, 2

0°C

Qm

(m3/

t)

Perm

eabi

lity

(mD

)

Seam

Ash

%

Seam

RD

g/c

c

Thic

knes

s (m

)

Pore

Pre

ssur

e (k

Paa)

Gas

Sat

urat

ion

%

LV @

Sea

m A

sh c

alc

20°C

&

Res

Tem

p (m

3/t)

Res

ervo

ir Te

mpe

ratu

re °C

Pore

Pre

ssur

e (k

Paa)

Gas

Sat

urat

ion

%

1 1.17 260 4.5 160 20 1.46 5.5 2161 47.5 21.44 37.8 739 93.22 0.79 250 6 160 17 1.43 5.6 2063 61.1 22.53 37.3 984 95.33 0.98 230 4.5 160 19 1.45 5.9 1867 49.2 22.46 36.2 690 94.24 2.64 245 6 160 19 1.45 6.1 2014 62.7 22.17 37.0 1131 88.15 2.41 300 7.5 80 18 1.44 5.5 2554 71.5 21.28 40.0 1475 95.56 1.56 290 9 80 17 1.43 5.6 2456 84.7 21.77 39.5 1867 97.17 1.78 290 7.5 80 18 1.44 6.1 2456 72.3 21.47 39.5 1475 94.88 4.47 305 8 80 18 1.44 5.9 2603 75.7 21.19 40.3 2112 83.69 1.32 345 9.5 25 20 1.46 5.7 2995 88.9 19.83 42.4 2995 88.9

10 2.76 340 11 25 18 1.44 5.8 2946 99.5 20.52 42.2 3241 95.711 3.19 335 10 25 18 1.44 6 2897 91.3 20.62 41.9 2897 91.312 1.47 335 11 25 19 1.45 5.9 2897 101.2 20.32 41.9 2995 99.713 1.16 320 9 25 17 1.43 5.9 2750 82.4 21.20 41.1 2750 82.414 2.96 375 11.25 7.5 19 1.45 5.75 3290 101.6 19.56 44.1 3437 99.915 3.25 360 11 6 18 1.44 6 3142 98.6 20.14 43.2 3142 98.616 0.80 350 10 6 19 1.45 6.2 3044 91.2 20.18 42.7 3044 91.217 2.14 395 10.75 3.5 20 1.46 5.55 3486 98.4 18.88 45.1 3486 98.418 1.52 350 10.5 0.5 19 1.45 6.35 3044 95.4 20.18 42.7 3044 95.4

Cla

ssifi

ed

Before Mining

Mining Affected

Reg

ion

Are

a (k

m2)

Dep

th (m

)

Mea

sure

d G

as C

onte

nt a

t Se

am A

sh, 2

0°C

Qm

(m3/

t)

Perm

eabi

lity

(mD

)

Seam

Ash

%

Seam

RD

g/c

c

Thic

knes

s (m

)

Pore

Pre

ssur

e (k

Paa)

Gas

Sat

urat

ion

%

LV @

Sea

m A

sh c

alc

20°C

&

Res

Tem

p (m

3/t)

Res

ervo

ir Te

mpe

ratu

re °C

Pore

Pre

ssur

e (k

Paa)

Gas

Sat

urat

ion

%

1 1.17 260 4.5 160 20 1.46 5.5 2161 47.5 21.44 37.8 739 93.22 0.79 250 6 160 17 1.43 5.6 2063 61.1 22.53 37.3 984 95.33 0.98 230 4.5 160 19 1.45 5.9 1867 49.2 22.46 36.2 690 94.24 2.64 245 6 160 19 1.45 6.1 2014 62.7 22.17 37.0 1131 88.15 2.41 300 7.5 80 18 1.44 5.5 2554 71.5 21.28 40.0 1475 95.56 1.56 290 9 80 17 1.43 5.6 2456 84.7 21.77 39.5 1867 97.17 1.78 290 7.5 80 18 1.44 6.1 2456 72.3 21.47 39.5 1475 94.88 4.47 305 8 80 18 1.44 5.9 2603 75.7 21.19 40.3 2112 83.69 1.32 345 9.5 25 20 1.46 5.7 2995 88.9 19.83 42.4 2995 88.9

10 2.76 340 11 25 18 1.44 5.8 2946 99.5 20.52 42.2 3241 95.711 3.19 335 10 25 18 1.44 6 2897 91.3 20.62 41.9 2897 91.312 1.47 335 11 25 19 1.45 5.9 2897 101.2 20.32 41.9 2995 99.713 1.16 320 9 25 17 1.43 5.9 2750 82.4 21.20 41.1 2750 82.414 2.96 375 11.25 7.5 19 1.45 5.75 3290 101.6 19.56 44.1 3437 99.915 3.25 360 11 6 18 1.44 6 3142 98.6 20.14 43.2 3142 98.616 0.80 350 10 6 19 1.45 6.2 3044 91.2 20.18 42.7 3044 91.217 2.14 395 10.75 3.5 20 1.46 5.55 3486 98.4 18.88 45.1 3486 98.418 1.52 350 10.5 0.5 19 1.45 6.35 3044 95.4 20.18 42.7 3044 95.4

Cla

ssifi

ed

12

GeoGAS

P Seam Reservoir Regions

Reg

ion

Are

a (k

m2)

Dep

th (m

)

Mea

sure

d G

as C

onte

nt a

t Se

am A

sh, 2

0°C

Qm

(m3/

t)

Perm

eabi

lity

(mD

)

Seam

Ash

%

Seam

RD

g/c

c

Thic

knes

s (m

)

Pore

Pre

ssur

e (k

Paa)

LV @

Sea

m A

sh c

alc

20°C

&

Res

Tem

p (m

3/t)

Res

ervo

ir Te

mpe

ratu

re °C

Gas

Sat

urat

ion

%

1 2.15 263 4.8 46.7 28 1.53 4.5 2186 18.99 38.0 56.12 2.03 288 5.9 27.1 28 1.53 4.5 2431 18.51 39.3 66.53 2.84 313 7.0 15.7 28 1.53 4.5 2676 18.04 40.7 76.74 1.41 332 7.9 10.3 28 1.53 4.5 2868 17.67 41.7 84.7

Classified

Reg

ion

Are

a (k

m2)

Dep

th (m

)

Mea

sure

d G

as C

onte

nt a

t Se

am A

sh, 2

0°C

Qm

(m3/

t)

Perm

eabi

lity

(mD

)

Seam

Ash

%

Seam

RD

g/c

c

Thic

knes

s (m

)

Pore

Pre

ssur

e (k

Paa)

LV @

Sea

m A

sh c

alc

20°C

&

Res

Tem

p (m

3/t)

Res

ervo

ir Te

mpe

ratu

re °C

Gas

Sat

urat

ion

%

1 2.15 263 4.8 46.7 28 1.53 4.5 2186 18.99 38.0 56.12 2.03 288 5.9 27.1 28 1.53 4.5 2431 18.51 39.3 66.53 2.84 313 7.0 15.7 28 1.53 4.5 2676 18.04 40.7 76.74 1.41 332 7.9 10.3 28 1.53 4.5 2868 17.67 41.7 84.7

Classified

GeoGAS

GM & P Seam Production Profiles

Based on well spacing 390 mLateral length in coal 900 mLaterals run down dip to vertical wellWhere structure permits, dual laterals are usedWells are oriented to avoid intersection by gateroads

13

GeoGAS

GM Production Profiles

0.0 0.5 1.0 1.5 2.0 2.5 3.0

Times (years)

Gas

Pro

duct

ion

(MC

FD)

Region 8 Region 9Region 10 Region 11Region 12 Region 13Region 14 Region 15Region 16 Region 17Region 18

RegionProduction.xls{RegionProduction}

Goonyella Middle Seam

GeoGAS

Example of Bottom Hole Pressures Applied

0

500

1000

1500

2000

2500

3000

3500

0 50 100 150 200 250 300 350 400 450 500

Time (Days)

Botto

m H

ole

Pres

sure

(kPa

a) Production constrained to 1200 MCFD

Unconstrained gas production

Region12bSpac390mProd.xls{BHPCompare}

14

GeoGAS

Gas Recovered Per Well and Remaining Gas Content

(1) Target is < 4 m3/t these wells

Remaining Gas Content Qm GM Seam

Region SIMED Data

File Days to Target Qm

Years to < 3 m3/t

PJ/Well to 50

MCFD

8 Reg8a 400 1.1 0.71 9 Reg9a 900 2.5 0.81 10 Reg10a 900 2.5 0.96 11 Reg11a 1000 2.7 0.93 12 Reg12a 900 2.5 1.00 13 Reg13a 1100 3.0 0.79 14 Reg14a 3000 8.2 0.93 15 Reg15a 2500 6.8(1) 0.96 16 Reg16a 2500 6.8(1) 0.90 17 Reg17a 3000 8.2(1) 0.78 18 Reg18a 9 m3/t after 15 yrs N/A N/A 8 Reg8b 600 1.6 1.44 12 Reg12b 1200 3.3 2.09 9 Reg9_192 350 1.0 0.52 9 Reg9_268 800 2.2 0.93

Cla

ssifi

ed

Remaining Gas Content Qm GM Seam

Region SIMED Data

File Days to Target Qm

Years to < 3 m3/t

PJ/Well to 50

MCFD

8 Reg8a 400 1.1 0.71 9 Reg9a 900 2.5 0.81 10 Reg10a 900 2.5 0.96 11 Reg11a 1000 2.7 0.93 12 Reg12a 900 2.5 1.00 13 Reg13a 1100 3.0 0.79 14 Reg14a 3000 8.2 0.93 15 Reg15a 2500 6.8(1) 0.96 16 Reg16a 2500 6.8(1) 0.90 17 Reg17a 3000 8.2(1) 0.78 18 Reg18a 9 m3/t after 15 yrs N/A N/A 8 Reg8b 600 1.6 1.44 12 Reg12b 1200 3.3 2.09 9 Reg9_192 350 1.0 0.52 9 Reg9_268 800 2.2 0.93

Cla

ssifi

ed

GeoGAS

P Seam Production Profiles

Wells peak lower and later than GM

0 1 2 3 4 5 6 7 8

Times (years)

Gas

Pro

duct

ion

(MCF

D)

Region 1

Region 2

Region 3

Region 4

RegionProduction.xls{RegionProduction}

P Seam

For single 900 m lateral

Remaining Gas Content

PJ/Well to 50 MCFD P Seam

Region Data File

*.dat Days to Target

Qm Years to <

3 m3/t Single Lateral

Dual Lateral

1 RegP1a 700 1.9 0.25 0.54 2 RegP2a 1300 3.6 0.33 0.69 3 RegP3a 2500 6.8 0.40 0.91 4 RegP4a 2500 6.8 0.46 1.06

Classified

Remaining Gas Content

PJ/Well to 50 MCFD P Seam

Region Data File

*.dat Days to Target

Qm Years to <

3 m3/t Single Lateral

Dual Lateral

1 RegP1a 700 1.9 0.25 0.54 2 RegP2a 1300 3.6 0.33 0.69 3 RegP3a 2500 6.8 0.40 0.91 4 RegP4a 2500 6.8 0.46 1.06

Classified

15

GeoGAS

Well Sequencing

58 wells in allFirst 28 shown here

Seam Data File

*.dat Well No Well Sequence

Single or Dual

LateralDate on Gas Mined

ThroughDays on

LineDays

NeededGas Drained

< Target

GM Reg9_192 INGM006 1 Single 15/05/07 1/10/13 2331 350 OK



GM Reg8a R8-01 4 Single 15/09/07 1/06/12 1720 400 OK

GM Reg8b R8-02 5 Dual 13/10/07 1/01/13 1906 600 OK








P RegP1a R1-01(P) 13 Dual 28/05/08 1/09/12 1557 700 OK

P RegP1a R1-02(P) 14 Single 6/08/08 1/11/18 3739 700 OK



GM Reg8b R8-05 17 Dual 22/07/09 1/02/15 2020 600 OK








P RegP2a R2-01(P) 25 Dual 24/07/10 1/07/15 1803 1300 OK




Cla

ssifi

ed

Seam Data File *.dat Well No Well

Sequence

Single or Dual

LateralDate on Gas Mined

ThroughDays on

LineDays

NeededGas Drained

< Target





GM Reg8b R8-02 5 Dual 13/10/07 1/01/13 1906 600 OK








P RegP1a R1-01(P) 13 Dual 28/05/08 1/09/12 1557 700 OK

P RegP1a R1-02(P) 14 Single 6/08/08 1/11/18 3739 700 OK



GM Reg8b R8-05 17 Dual 22/07/09 1/02/15 2020 600 OK








P RegP2a R2-01(P) 25 Dual 24/07/10 1/07/15 1803 1300 OK




Cla

ssifi

ed

GeoGAS

GM & P Seam Pre Drainage Gas Production

Time (years)

Gas

Pro

duct

ion

(TJ/

day)

P SIS WellsLW Goaf GasUIS risersGM SIS Wells

RegionProduction xls{WellConstants}

16

GeoGAS

Uncertainty

GeoGAS

Predrainage Gas Production

UISDelays in mining will impact on gas production Air dilution under negative pressure □

SISNot tied to mining Pipeline quality gas Design and operational risks Changes to mine plan and schedule

17

GeoGAS

Modelling Uncertainty

Uses the three main variable parametersGas contentSorption capacityPermeability

Aiming for combined output of 1 standard deviation for these parameters

1 param 2 params 3 paramsP90 0.1257 0.01253 0.001253P68.3 0.4088 0.1265 0.04005P50 0.6745 0.3186 0.1573P31.7 1 0.6221 0.41P10 1.645 1.311 1.101

# of Standard DeviationsP Case

GeoGAS

Gas Production Distribution

0 100 200 300 400 500 600 700 800 900 1000

Days on Line

Gas

Pro

duct

ion

(MCF

D)

Mean

1x Std Dev

2x Std Dev

Probability.xls{Outputs}

Region 12

18

Probability Distribution SIS Well Production

Days Required to Reach Target Gas Content

Time (years)G

as P

rodu

ctio

n (T

J/da

y)

Probability.xls{ProbSummaryOutput}

Mean +/- 1 Standard Deviation

1 to 2 Standard Deviations

Num

ber o

f SIS

Wel

ls

Probability xls{Wells}

Region X Region Y+2*1 Std Dev 650 2000+1 Std Dev 750 2250Mean 900 2750-1 Std Dev 1200 4000-2 Std Dev 1750 5500

GeoGAS

Conclusions

A drilling and drainage schedule was defined that utilised the available drainage time at the widest spacing to produce the required level of gas but with priority on satisfying mine gas management requirements. The power station off-take is a managed, but independent and subsidiary outcome to mine gas management. Gas production begins to tail down with the completion of SIS well drilling from 2016~2020. Maintenance of gas production beyond this time is expected with higher rates of gas capture of longwall gas and with capture of gas from the destressed reservoir above the GM seam.The SIS methodology has been deliberately “simple” and timely.

19

GeoGAS

Conclusions (cont)

An assessment of SIS well modelling output has shown a wide range of production variability on a well-by-well basis. This uncertainty can be managed by bringing forward production wells and operating at higher well head pressures if production exceeds demand and is consistent with mining requirements.As indicated in probability modelling, variations in remaining gas content from SIS drilling can be high.Realisation of the project gas production rates will require operating the field at as low a well head pressure as possible. Modelling assumed a wellhead pressure of 150 kPag. Intended field pressure beyond 2010 is 100 kPag.

Documents

Moranbah North Coal Seam Gas Development – Technical and Statutory · 2008-02-06 · 1 GeoGAS Moranbah North Coal Seam Gas Development – Technical and Statutory Anglo Coal Australia