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) SEQUENCE 1995) LITHOSTRATIGSEQUENCE LITHOSTRATIG 600 600 AGEAGE DF UJ UJ SYSTEM TRACT SYSTEM TRACT 25°40'S CLJT STRATIGRAPHY RAPHYSTRATIGRAPHYSliwa, RAPHY Sliwa, (a) (b) CLJT et al et al STAGE (Ma)(Ma) GAMMA STAGE GAMMA CCM EPOCH EPOCH PERIOD PERIOD 500 500 (after Olsen et (after Olsen et 25°40'S 30 (a) CCM STAGE STAGE SEQUENCE (after SEQUENCE SEQUENCE (after after after after after SEQUENCE after SEQUENCE afteret al.SEQUENCE et al. GAMMA RAY RAY GAMMA RAY RAY m Hoffman Hoffman 2009) Reilly. Hoffman 2009) Reilly. Hoffman McMillop Hoffman McMillop McMillop 2015) EPOCH EPOCH al. 1995) al. 1995) McMillop 2015) PERIOD PERIOD Olsen Hamilton et Hamilton et Olsen 2014 2014 LITHOSTRATIGAPHY LITHOSTRATIGAPHY 400 AGE(Ma) AGE(Ma) 400 Reilly unpublished) LITHOSTRATIGAPHY LITHOSTRATIGAPHY Unpublis Unpublis Reilly unpublished) et al. et al. et al. (after STRATIGRAPHY et al. (after STRATIGRAPHY (after STRATIGRAPHY 26°00'S SYSTEMS TRACT (after TRACT SYSTEMS 20 STRATIGRAPHY (after STRATIGRAPHY (after STRATIGRAPHY (after STRATIGRAPHY (after (after Hamilton 2011) SYSTEMS TRACT (after TRACT SYSTEMS GAMMA RAY TIPTON 1 TIPTON RAY GAMMA (after (after Hamilton 2011) % 2009 2015 -hed 2009al. 2014)2015 -hed al. 2014) W240 W240 Durabilla, 26°00'S 300 300 10 GUBBERAMUNDA KIMMERIDGIAN 0 25 50km 200 200 KIMMERIDGIAN 26°20'S W310 W310 0 0 20 40 60 80 100 m Durabilla, above Height WESTBOURNE above Height TST LL W330 WESTBOURNE W330 26°20'S 100 100 Late Late TST Coal plies number 0 0 OXFORDIANOXFORDIAN LST SPRINGBOK SPRINGNOKSPRINGBOK 26°40'S LST W340 W340 0 5 10 0 10 20 30 40 J50.0J50.0 26°40'S Coal ply thickness, m PC and CH ply thickness, m W410 W410 Chinchilla Upper 60 70 CALLOVIAN UJ CALLOVIAN UJ 27°00'S (c) (d) HST 50 CLJT 60 Wambo Undulla CLJT HST CCM W420 W420 27°00'S Nose 50 CCM Juandah Lower 40 BATHONIAN WALLOON Average coal ply Average thicknesses BATHONIAN W440 W440 thicknesses are 1.01 40 for PC and CH plies Tangalooma Dalby 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 WALLOON 30 K W460 Taroom W460 27°20'S Kogan CCM respectively m in the UJ, CLJT and W470 W470 20 CCM respectively Middle Middle BAJOCIANBAJOCIAN LEGEND Anticline 20 W480 W480 % Percentage, J40.0 Durabilla % Percentage, J40.0 10 LST W510 W510 27°40'S 10 JURASSIC LST Walloon subcrop JURASSIC PC Primary channel 27°40'S AALENIANAALENIAN 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 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 MS Marginal swamp TOARCIANTOARCIAN HST 28°00'S W550 W550 Coal swamp EVERGREEN Coal ply number in 28°20'S Code 0 TST Sandstone boreholes Fig. 6. Coal (a) and channel PLIANSBACHIANPLIANSBACHIAN J Region 1 TST J Dirty Sandstone28°20'S SBSB 2 2 J20.0J20.0 Region 2 W570 W570 >=90 60-90 N (b)ply thickness against the Early Siltstone Region 3 Early W575 W575 28°40'S Region 4 SINEMURIANSINEMURIAN LST W580 PRECIPICE W580 Mudstone 0 25 50 km SB 1 J10.0 30-60 <30 heightCode 5 above horizon LST 28°40'S SB 1 W610J10.0 W610 Shaly coal Code 6 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 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..