Geometry and Distribution of Channel and Coal in Walloon Coal Measures, Surat Basin, Australia

Fengde Zhou ab; Stephen Tyson ab; Daren Shields 1, Joan Esterle ab CCSG Research Review, 9 December 2016 a School of Earth Sciences , The University of Queensland PROJECT: SURAT SUPERMODEL II – b Centre for Coal Seam Gas, The University of Queensland AN INTEGRATED GEOLOGICAL FRAMEWORK FOR CSG

INTRODUCTION

Understanding the geometry, distribution and controls on thick coal is fundamental to understanding coal seam gas reservoirs. In the Jurassic Walloon Subgroup coal measures, the spatial continuity of the coal seams is highly variable and often difficult to map and predict even with closely spaced (<1000 m) drilling. As a result, stochastic models have been built to simulate reservoir geometries of coals and their interburden lithologies within a continental system of fluvial channels, floodplains and lakes and mires. This study examines the statistical distribution of coal plies and channels at a basin and local scale, to determine whether a predictive pattern can be developed for the stratigraphic subdivisions and basin location relative to interpreted higher and lower accommodation settings reflecting the underlying basement proximity, syndepositional faulting and differential compaction. STUDY AREA, DATA AND STRATIGRAPHY

Fig. 2. Cumulative coal thickness per borehole overlain on an isochore map of Walloon Coal Measures unit thickness. The main structural folds as well as the outline of the underlying Fig. 1. (a) Locations of the Bowen Basin are also Walloon Subcrop, boreholes shown. Top right with/without well markers inset figure showing and logging data, five local a vertical section of model areas, and 33 coal Basement, Bowen resources areas (DNRM, and Surat Basins. 2016). (b) Locations of the Study area, Surat Basin, Bowen Basin and Clarence Moreton Basin in Australia.

148°00'E 148°24'E 148°48'E 149°12'E 149°36'E 150°00'E 150°24'E 150°48'E 151°12'E 1995) 1995) 1995) SEQUENCE 1995) LITHOSTRATIGSEQUENCE LITHOSTRATIG 600 600 AGEAGE AGEAGE DF UJ UJ SYSTEM TRACT SYSTEM TRACT 25°40'S CLJT

STRATIGRAPHY RAPHYSTRATIGRAPHYSliwa, RAPHY Sliwa, (a) (b) CLJT

et al et al

et al et al STAGE STAGE

(Ma)(Ma) (Ma)STAGE (Ma) GAMMA STAGE GAMMA CCM

EPOCH EPOCH

EPOCH EPOCH PERIOD PERIOD PERIOD PERIOD 500 500

(after Olsen et (after Olsen et 25°40'S 30 (a) CCM

SEQUENCE SEQUENCE SEQUENCE

STAGE STAGE SEQUENCE SEQUENCE (after SEQUENCE SEQUENCE (after

SEQUENCE SEQUENCE SEQUENCE

after SEQUENCE after after after SEQUENCE after SEQUENCE afteret al.SEQUENCE et al. GAMMA RAY RAY GAMMA RAY GAMMA

RAY RAY m Hoffman Hoffman 2009) Hoffman 2009)

Hoffman Hoffman 2009) Reilly. Hoffman 2009) Reilly.

Hoffman McMillop McMillop 2015) Hoffman McMillop McMillop 2015)

EPOCH EPOCH

al. 1995) al. 1995)McMillop 2015) McMillop 2015)

PERIOD PERIOD

Olsen Olsen Hamilton et Hamilton et

Olsen Olsen 2014 2014

LITHOSTRATIGAPHY LITHOSTRATIGAPHY LITHOSTRATIGAPHY 400 AGE(Ma)

AGE(Ma) 400

Reilly unpublished) Reilly unpublished) LITHOSTRATIGAPHY LITHOSTRATIGAPHY LITHOSTRATIGAPHY

Unpublis Reilly unpublished) Unpublis Reilly unpublished)

STRATIGRAPHY (after STRATIGRAPHY (after STRATIGRAPHY et al. (after STRATIGRAPHY et al. et al. (after STRATIGRAPHY et al. (after STRATIGRAPHY (after STRATIGRAPHY

26°00'S

SYSTEMS TRACT (after TRACT SYSTEMS (after TRACT SYSTEMS 20

STRATIGRAPHY (after STRATIGRAPHY (after STRATIGRAPHY

STRATIGRAPHY (after STRATIGRAPHY (after STRATIGRAPHY (after STRATIGRAPHY (after STRATIGRAPHY

(after (after Hamilton 2011) (after Hamilton 2011)

SYSTEMS TRACT (after TRACT SYSTEMS (after TRACT SYSTEMS GAMMA RAY TIPTON 1 TIPTON RAY GAMMA 1 TIPTON RAY GAMMA (after (after Hamilton 2011) (after Hamilton 2011) % 2009 2015 -hed 2009al. 2014)2015 -hed al. 2014)

W240 W240 Durabilla, 26°00'S 300 300 10 GUBBERAMUNDA GUBBERAMUNDA KIMMERIDGIAN KIMMERIDGIAN 0 25 50km 200 200

KIMMERIDGIAN KIMMERIDGIAN 26°20'S W310 W310 0

0 20 40 60 80 100 m Durabilla, above Height WESTBOURNE WESTBOURNE above Height

TST LL TST WESTBOURNELL W330 WESTBOURNE W330 26°20'S 100 100 Late Late Late Late TST TST Coal plies number 0 0 OXFORDIANOXFORDIAN OXFORDIANOXFORDIAN LST LST SPRINGNOKSPRINGBOK SPRINGNOKSPRINGBOK 26°40'S LST LST W340 W340 0 5 10 0 10 20 30 40

J50.0J50.0 J50.0J50.0 26°40'S Coal ply thickness, m PC and CH ply thickness, m W410 W410 Chinchilla Upper Upper 60 70 CALLOVIAN CALLOVIAN UJ CALLOVIAN CALLOVIAN UJ 27°00'S (c) (d) HST HST 50 CLJT 60 Wambo Wambo Undulla CLJT HST HST CCM W420 W420 27°00'S Nose 50 CCM Juandah Lower Juandah Lower 40 BATHONIAN BATHONIAN WALLOON WALLOON Average coal ply Average thicknesses BATHONIAN BATHONIAN W440 W440 thicknesses are 1.01 40 for PC and CH plies Tangalooma Tangalooma Dalby TST TST 30 27°20'S m, 0.64 m and 0.97 m thicker than 5 m are W450 W450 for the UJ, CLJT and 9.5 m, 9.7 m and 7.9 TST K TST WALLOON K WALLOON 30 K K Taroom W460 Taroom W460 27°20'S Kogan CCM respectively m in the UJ, CLJT and

W470 W470 20 CCM respectively Middle Middle Middle BAJOCIANBAJOCIAN Middle BAJOCIANBAJOCIAN LEGEND Anticline 20

W480 W480 % Percentage, J40.0 Durabilla J40.0 Durabilla % Percentage, J40.0 J40.0 10 LST LST W510 W510 27°40'S 10 JURASSIC JURASSIC LST LST Walloon subcrop

JURASSIC JURASSIC PC Primary channel 27°40'S AALENIANAALENIAN AALENIANAALENIAN HUTTON W520 HUTTON W520 0 0

CH Channel >3

0-5

>40

5-10

0-0.5

0.5-1

1-1.5

1.5-2 2-2.5

SBSB 4 4 J30.0J30.0 SBSB 4 4 J30.0J30.0 2.5-3

10-15

15-20

20-25

25-30 30-35 Floodplain 35-40 W540 W540 FP 28°00'S Syncline Anticline Coal ply thickness range, m PC and CH ply thickness range, m HST SBSB 3 3 HST SBSB 3 3 MS Marginal swamp TOARCIANTOARCIAN TOARCIANTOARCIAN HST HST 28°00'S W550 W550 Coal swamp EVERGREEN EVERGREEN Coal ply number in

28°20'S Code 0 TST TST Sandstone boreholes Fig. 6. Coal (a) and channel PLIANSBACHIANPLIANSBACHIAN PLIANSBACHIANPLIANSBACHIAN J J Region 1 TST J TST J Dirty Sandstone28°20'S SBSB 2 2 J20.0J20.0 SBSB 2 2 J20.0J20.0 Region 2 W570 W570 >=90 60-90 N (b)ply thickness against the Early Early Siltstone Region 3 Early Early W575 W575

28°40'S Region 4 SINEMURIANSINEMURIAN SINEMURIANSINEMURIAN LST LST PRECIPICE W580 PRECIPICE W580 Mudstone 0 25 50 km SB 1 J10.0 SB 1 J10.0 30-60 <30 heightCode 5 above horizon LST LST 28°40'S SB 1 J10.0 SB 1 W610J10.0 W610 Shaly coal Code 6 HETTANGIAN HETTANGIAN Coal 148°00'E 148°24'E 148°48'E 149°12'E 149°36'E 150°00'E 150°24'E 150°48'E 151°12'E 151°36'E Durabilla. Histograms of coal HETTANGIAN HETTANGIAN Fig. 5. Distribution of total coal ply number (c) and channel (d) ply Fig. 3. Sequence and litho-stratigraphic subdivisions of the Fig. 4. Example of well logs thickness. Surat Basin (after Shields and Esterle, 2015). analysis at the well Lauren 51. for the WCM. RESULTS

9 8 7 6 5 4 Width, km Width, 3 2 From MinesOnlineMaps, 2016 1 From local areas 0 0 5 10 15 20 25 Length, km Fig. 8. Width against length measured from coal Fig. 7. Isopleth of Primary channel and channel plies thicker than 5 m in (a) the Upper Juandah, (b) the Combined Lower resources areas and distribution area with two or Juandah-Tarooms and Primary channel and channel plies thicker than 3 m in (c) the Condamine Coal Measures. more coal plies thicker than 2 m from local areas.

CONCLUSIONS ACKNOWLEDGEMENTS • The cumulative coal thickness and coal We thank Renate Sliwa and the Office plies number is highest along the eastern of Groundwater Impact Assessment for margin of the basin. provision of formation tops and a • Greater number of thick coal plies is closer normalised wireline data set. We to greater number of PC and CH but they acknowledge all the coal seam gas are not overlayed each other. companies who provide data to the • This observation appears consistent with DNRM, Centre for Coal Seam Gas for the sequence stratigraphic model of thicker the support, and Schlumberger for coal plies forming in times of relatively providing the licenses of Petrel. Fig. 9. A cross section showing the facies distribution in boreholes from North to Southeast. slow base level rise.