Hydroseismic lessons from Oklahoma: Cautionary tale for the Karoo

1. Hydroseismic lessons from Oklahoma: Cautionary tale for the Karoo Chris Hartnady Umvoto Africa (Pty) Ltd, Muizenberg, RSA (http://www.umvoto.com) AfricaArray 2011 Workshop University of the Witwatersrand, Johannesburg 21 November 2011

2. In the recent news • Is there a connection to gas-shale ‘fracking’?

3. Outline • Shale gas: brief global perspective • Oklahoma developments • Seismotectonic context of recent earthquake swarms • Probable anthropogenic trigger operations • Implications for Karoo

4. EIA 2011 resources assessment 388 862 1275 681 TCF numbers refer to ‘technically recoverable’ resource 396 485 774 SA ranked fifth in world (TCF = trillion cubic feet)

5. Geological setting of natural gas Why target the depleted source?

6. Oil production and price: recent history Hubbert’s Peak

7. Era of ‘extreme energy’ • “… humanity has embarked on the era of extreme energy, where there are no simple solutions. The inexpensive, high-yield fossil fuels that powered the industrial revolution …are dwindling, and all of them emit dangerous levels of greenhouse gases. While enormous amounts of natural gas, oil, and coal remain, the portions of those fuels that were cheapest and easiest to produce are now mostly gone, and producing remaining reserves will entail spiraling investment costs and environmental risks.” (Aspect of ‘water-energy nexus’) • Richard Heinberg, fellow of Post-Carbon Institute, 2011

8. What’s up in Oklahoma? • from B.J. Cardot, 2008

9. Arkoma Basin shale-gas play • from B.J. Cardot, 2008

10. Basin stratigraphy CAPE-KAROO CHRONOSTRAT CORRELATION • from Cardot, 2008 ECCA DWYKA WITTEBERG BOKKEVELD NARDOUW CEDARBERG PAKHUIS PENINSULA

11. Oklahoma tectonics • from Cardot, 2008

12. USGS epicentres: 2009-2011

13. Cherokee Platform epicentres

14. 2010-2011 activity near Wilzetta Fault

15. Recent ‘pad’ developments 1995 Feb 08 • Google Earth change analysis 2008 Apr 15

16. Pad details 2005 Nov 03 2008 Apr 15

17. Hunton ‘retrograde oil cut’ play • "We really have discovered a new formation -- a new oil reservoir -- which is a rarity in Oklahoma," said Mohan Kelkar, a professor of petroleum engineering at TU. Using a $3 million grant from the Department of Energy and $9.4 million from Tulsa-based Marjo Oil Co., Kelkar is studying the characteristics of this "unusual" oil formation to determine the best way to recover oil at a reasonable cost. "If we can understand it and come up with better production techniques, we can really optimize the production from this reservoir," Kelkar said. For years, the Hunton was ignored by producers because the reservoir contains large amounts of saltwater. The expense of removing that water was too great, most people thought. • … But before oil can be produced in profitable volumes, producers must first find an affordable way to dispose of massive amounts of water. Some oil companies, including Altex Resources Inc., already have mastered the process. … The San Antonio-based company uses high-capacity saltwater disposal wells, each of which are tied to multiple oil wells. Some disposal wells are capable of handling as much as 3,500 barrels of saltwater each day, said Kim Booth, Altex operations manager. "We have incredible infrastructure in place for displacing this water", Booth said. From: http://www.drillthis.com/history-hunton-field-mystery.html

18. Karoo earthquakes!? • 2011 May 14 16:10 SAST • Local magnitude (ML) 4.1 M6.3;1969 M7.3;~10.6k BP M6.2;1809 Senqu Seismic Belt USGS

19. Regional lithospheric stress patterns • Dynamic model of vertical integrated stress anomaly (VISA) • Karoo within ‘Cape Stress Province’ (CSP) (Hartnady, 1998) bounded on N by ‘Senqu Seismic Belt’ • Reflects high, E-W compressive stresses generated by break-up of Africa between Nubia (NU) and Somalia (SO) plates, forcing convergence in S NU SO CSP from Bird, Liu and Rucker, 2008

20. Conclusions • Oklahoma’s largest earthquake cannot be directly related to fracking operations in the Woodford gas-shale (except …) • Since 2008 there has been a spectacular increase in (micro-) earthquake swarm activity in the west-central Cherokee Platform • Most probably related to ‘retrograde oil cut’ operations in the underlying Hunton limestones, which inherently depend on high-volume saltwater injection-disposal wells • Lessons for the Karoo shale-gas proposal: • Fluid-injection-triggered hydroseismicity is a real techno-hazard (even more so here, because of prevailing crustal stress regime) • Disposal of ‘produced’ (contaminated) waste-water requires stringent regulation, informed by both hydogeological and seismotectonic science

21. Thank you!

22. Shell’s genius Triple-major graduate of University of Chicago (Geology, Physics, Maths) Short academic career at Columbia University, NY Geophysicist heading Shell Research Laboratory in Houston, Texas Adjunct professor at Stanford and UC Berkeley 1955 election to US National Academy of Sciences 1956 paper suggested possibility of 1970 peak in US oil production Acknowledgement M. King Hubbert 1903-1989 22

23. Hubbert’s scientific heritage • Hubbert, M.K. (1937).Theory of scale models as applied to the study of geological structures. Geological Society of America Bulletin 48: 1459-1520. • Hubbert, M.K. (1940).The theory of ground-water motion. Journal of Geology 48: 785-944. • Hubbert, M.K. (1953).Entrapment of petroleum under hydrodynamic conditions. American Association of Petroleum Geologists Bulletin 37: 1954-2026. • Hubbert, M.K. and Rubey, W.W. (1959). Role of fluid pressure in mechanics of overthrust faulting. Geological Society of America Bulletin 70:115-166. Paradigm-shifters