Hydroseismic lessons from Oklahoma: Cautionary tale for the Karoo

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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
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In the recent news

• Is there a connection to gas-shale fracking?

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Outline

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

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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)
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Geological setting of natural gas
Why target the depleted source?
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Oil production and price recent history
Hubberts Peak
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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

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Whats up in Oklahoma?

• from B.J. Cardot, 2008

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Arkoma Basin shale-gas play

• from B.J. Cardot, 2008

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Basin stratigraphy
CAPE-KAROO CHRONOSTRAT CORRELATION
ECCA
DWYKA
WITTEBERG
BOKKEVELD
NARDOUW

• from Cardot, 2008

CEDARBERG
PAKHUIS
PENINSULA
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Oklahoma tectonics

• from Cardot, 2008

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USGS epicentres 2009-2011
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Cherokee Platform epicentres
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2010-2011 activity near Wilzetta Fault
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Recent pad developments
1995 Feb 08

• Google Earth change analysis

2008 Apr 15
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Pad details
2005 Nov 03
2008 Apr 15
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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-fiel
d-mystery.html
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Karoo earthquakes!?

• 2011 May 14 1610 SAST
• Local magnitude (ML) 4.1

M6.31969
M7.310.6k BP
M6.21809
Senqu Seismic Belt
USGS
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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
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Conclusions

• Oklahomas 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

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Thank you!
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Shells genius
Acknowledgement

• 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

M. King Hubbert 1903-1989
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Hubberts 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