Queensland’s Eromanga oil – where did it go?

1. Use Powerpoint’s View>Notes Page to see transcript Queensland’s Eromanga oil – where did it go? David Lowry PESA June 2018

2. G.A.B Depth to base Ransley et al. 2012 A3 Fig 2 (CSIRO)

3. Eromanga Basin study area C Horizon Depth map

4. Toolebuc is shallowest mapping horizon. The ‘C’ horizon is the best mapping horizon and marks a marine transgression. There is no sign of structural growth in the reflectors above the Toolebuc. – Layer cake

5. Source Inland Field (5 mmbbl) several horizons; not full to spill Morney high has a thin residual oil column Source rocks in Toolebuc shale; Birkhead coal; Poolowanna coal

6. Lots erosion over major anticlines – how much elsewhere? • Need for: • Maturity modelling • Migration patterns • Estimate stripping with sonic log and compaction trend

7. Selecting a ‘Normal Compaction Trend’ Beanbush-1 Sonic (µsec/ft) Gamma Ray

8. Selecting Formations Beanbush-1 Winton Fm “Toolebuc”

9. Choose the shape and equation of the curve Beanbush-1 Winton NCT DT = 194 – depth* 0.072 DT is sonic transit time in microsec/ft; inverse of velocity Depth below RT in metres (Lowry & Evans, 2011)

10. Choosing an NCT for circum-Toolebuc Beanbush-1 Equation developed for this study is a quadratic (“Q5”) DT= Z2*0.084763 - Z*44.107 +5359

13. Stonehenge-1 how much stripping? Winton siltstone NCT No stripping 1 2 3 4

14. Stonehenge-1 how much stripping? Q5 NCT No stripping 600 m 620 m 640 m 660 m

15. Stonehenge-1 how much stripping? Winton siltstone NCT No stripping 620 m 640 m 660 m 680 m

16. Comparison of stripping estimates (m) Dashed line: Wallumbilla Solid line: Winton Keany et al (2016) Mavromatidis & Hillis (2005) Lowry & Evans (2011) Toby-1 Copai-1 Tinchoo-1 Steward-1 Marengo-1 Cuddapan-1 Hammond-1 Mackillop-1

17. Eromanga Basin study area C Horizon Depth map

18. E W Ground level Sea level Base Winton Toolebuc Hughes-1 Marduroo-1 Corona-1 “C” Pennycoed Ck-1 Scotty Ck-1 Jillaroo-1 Silsoe-1 Alfred Downs-1 Base Eromanga East-West section Maneroo Platform

19. W E Stripped Winton Base Winton Toolebuc “C” Base Eromanga East-West section Maneroo Platform

20. E W Stripped Winton End Winton depositional surface Ground level Sea level Base Winton Toolebuc “C” Base Eromanga East-West section Maneroo Platform

21. W E End Winton depositional surface Eventual Ground level Base Winton Toolebuc “C” Base Eromanga East-West section Maneroo Platform

22. PRELIMINARY Restored C Cadnaowie restored to maximum burial 1850 m contour highlighted

24. Corona-1 C Horizon Depth map

25. DST Recovered 0.4 bbl waxy oil + water. Intra-Westbourne sand. Log analysis: 1 m clean oil; 1 m transition zone

26. Corona-1 Burgamoo-1

27. Good coal source in Birkhead in Burgamoo-1 Coals marked by low densities

28. Carella Creek North-1

29. Birkhead coal has high HI, shale-siltstone has low HI. Coal (and only coal) has good source potential

30. Birkhead coal has high HI, shale-siltstone has low HI. Coal (and some shale) has good source potential

31. Burgamoo-1 No log digits available Hand digitise image of sonic log

32. Burgamoo-1 Temperature matched by heat flow 85 mW/m2 DST Corrected wireline

33. Burgamoo-1 maturity models 460 m stripping No stripping Birkhead Ro 0.72% Birkhead Ro 0.9%

34. Bessies-1 Vagaries of calibrating a maturity model Modelled maturity Conventional Vitrinite Reflectance

35. Tmax fair but suppressed over Toolebuc (conversion algorithm from Hall (2015)) Modelled maturity Bessies-1 Vagaries of calibrating a maturity model FAMM good Conventional Ro useless VIRF best

40. Mahlstead 2016 Geos4 Rept 20161216 for GSQ Kerogen kinetics

41. Geos4 sample G016505 Birkhead coal HI 344 Pepper &Corvi (1995) oil adsorption threshold 100 mg oil/g TOC

43. Exploration Lessons learned: Innovate. Exploring for oil in old places is hard and needs new approaches. It helps to keep up a broad education to fertilise your creativity. Analyse. What do you want to achieve? What do you have? How do you get from one to the other? Be critical. Do not just pluck technologies off the shelf. Understand and maybe develop your own. Acknowledgments : 60 years of stimulation by colleagues at University Auckland, Geological Survey WA, WAPET, Lasmo, Sagasco/BERL/Origin Fluid Energy for use of Petrosys; past and future collaboration

44. ABSTRACT Queensland’s Eromanga oil – where did it go? Peak generation of oil in the Eromanga Basin happened in the Cretaceous – around 90 Ma. But the basin has since undergone regional warping and stripping prior to the Eocene, followed by local compressional folding in the Miocene. Modern structure is thus a poor guide to migration at peak generation. Careful manipulation of sonic logs allows stripping estimates leading to structure maps restored to maximum Cretaceous burial. These maps allow determination of drainage areas and routes. Maturity modelling of wells reveals the location of kitchens and suggests rough estimates of volumes expelled. Previous publications of maturity maps and models have largely neglected the evidence for stripping and the models are a poor basis for exploration. The location of kitchens is not restricted to areas of current deep burial. For example the enigmatic oil occurrence at Corona-1 comes from a small shallow Birkhead kitchen made mature by 700 m of former extra burial and a very high heat flow. The work has the potential to inspire further exploration by reducing charge risk of prospects in areas presently neglected. David Lowry david@lowryresources.com.au