0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

90.0

100.0

Ste

el_

Cal

ib1

Ste

el_

calib

2

GG

-9 B

righ

t

GG

-3 B

righ

t

GG

-3 D

ull

GG

-27

Du

ll

GG

-33

Du

ll

GG

-8 B

righ

t

GG

-37

Du

ll

GG

-4 D

ull

GG

-12

Bri

ght

GG

-2 B

righ

t

GG

-13

Du

ll

GG

-13

Bri

ght

GG

-5 B

righ

t

GG

-26

Bri

ght

GG

-11

Du

ll

GG

-36

GG

-23

Bri

ght

GG

-24

GG

-20

GG

-29

GG

-18

GG

-22

GG

-34

GG

-39

GG

-38

GG

-14

GG

-16

Bri

ght

GG

-16

Du

ll

GG

-35

Bri

ght

GG

-21

GG

-15

Bri

ght

GG

-30

Bri

ght

GG

-25

Bri

ght

GG

-25

Du

ll

GG

-28

Bri

ght

Sho

re

Guluguba 2

mean

stdev

mode

ACKNOWLEDGEMENT

This research has been conducted with the support of the Centre for

Coal Seam Gas (UQ) and its industry members – APLNG, Arrow

Energy, QGC and Santos.

INTRODUCTION

Developing a synthetic grid block model for coal seams in the Surat Basin

Karina Barbosa - School of Earth SciencesSupervisors: Prof. Joan Esterle and

Prof. Marc Ruest

The CSG industry in the Surat Basin will benefit fromnumerical modelling simulations that take intoaccount more realistic coal characterization. Thesubbituminous coal is texturally different. The coalsare jointed and cleats are poorly developed at lowrank, except for some incipient cleats in the fewbright bands. The fracture toughness is very high,perhaps double, relative to more brittle bituminous(high rank) coals. However, strength data suggeststhat the low rank coals are weak. The juxtaposition ofthin tough but jointed coal lithotypes (centimetre todecimetre scale) against greasy claystones layersmakes the laboratory testing of the strength of intactrock a difficult task.

METHODOLOGY

ITA

SCA

, 20

15

Numerical modelling approach (Potyondy and Cundall, 2004)

Synthetic Grid Block

DFN properties (Joints and Cleats) and DFN

dimensions

COAL

DFN per lithotype

PFC

FLAC

COUPLED MODEL

Interburden

25*25*10(m) grid block of Walloon coal

Characterisation of coal and interburden

PRELIMINARY RESULTS

SSRH

SILC

SSRH

JK DWT

REFERENCES1. BOURGEOIS, F.S. and BANINI, G.A, 2002. A portable

load cell for in-situ ore impact breakage testing.

International Journal of Mineral Processing, 65 (1), 31-

54.

2. ITASCA CONSULTING GROUP INC., 2015—PFC3D

(particle flow code in three-dimensions). Suite version

5.0. Itasca Consulting Group Inc. (User’s manual).

Minneapolis, Minnesota: ICG.

3. MEDHURST, T.P., 1996—Estimation of the in-situ

strength and deformability of coal for engineering

design. PhD thesis. Brisbane: The University of

Queensland.

4. POTYONDY, D.O. AND CUNDALL, P.A., 2004—A bonded-

particle model for rock. International Journal of Rock

Mechanics and Mining Sciences, 41 (8), 1,329–64.

5. RUDD, R. 2016. Variation in joint spacing in layered

sedimentary rocks, Walloon coal measures. Honours

thesis in Geology at the University of Queensland.

6. TRUEMAN, R., and MEDHURST, T.P., 1994—The

influence of scale effects on the strength and

deformability of coal. IV CSMR/ Integral Approach to

Applied Rock Mechanics, ed. M. Van Sint Jan, 1, 103-

114. Santiago: Sociedad Chilena de Geotecnia.

Modified from TRUEMAN and MEDHURST, 1994

Mudstone

Coal D8 seam low ash Banded

Coal C6 seam Dull

≈200 Cylinders

≈2000 Particles

Coal C8 seam Banded white marks

Coal C8 seam Banded

Next: Synthetic Grid Block Analysis

Numerical evaluation of the influence of naturalfractures (cleats and/or joints) using the syntheticgrid block model for the Surat Basin.

Calibration of the model bycomparison with previous models,well tests and production profilesconducted for the Surat Basin.

0

10

20

30

40

50

60

70

80

0 0.5 1 1.5 2 2.5 3

t10

%

Ecs

t10 vs Ecs

mudstone D6 dull D8 banded

0

5

10

15

20

25

30

35

40

45

50

0 0.5 1 1.5 2 2.5 3

t10

%

Ecs

Mudstone t10 vs Ecs

45 x 37.5 31.5 x26.5 22.4 x 19

16 x 13.2 Trendline