1. The study found high methane concentrations in drinking water wells located within 1 km of active shale gas wells, which had a thermogenic isotopic fingerprint matching the Marcellus gas. Wells further than 1 km had lower methane concentrations and different isotopic compositions. 2. No evidence was found of chemical contamination of drinking water from shale gas operations. However, some data showed possible hydraulic connectivity between deep Marcellus formations and shallow aquifers in Pennsylvania. 3. Disposal of produced water into surface water poses significant risks of salinization, accumulation of toxins like barium and radionuclides, with impacts extending hundreds of meters downstream. Sustainable shale gas development needs to address environmental issues from

1. Methane and Water Contamination
Associated with Shale Gas Development
and Hydrofracking
Avner Vengosh
Nicholas School of the Environment,
Duke University

3. What are the environmental risks
associated with shale gas drilling and
hydro-fracturing?
Water
• Does shale gas drilling and hydro-fracking cause
contamination of drinking water wells?
• Does produced water disposal cause long-term ecological
effects and health risks?

4. Does shale gas drilling and hydro-fracking
cause contamination of drinking water wells?
Figure from Scientific American Magazine, November 2011

5. Isotopic fingerprinting of methane source
13C – 13C/12C
CH4
2H – 2H/H

6. Proceedings of National
Academy of Sciences,
May 17, 2011

7. Duke research in Pennsylvania and New York

8. Definition of active versus non-active wells:
Private wells located <1km from a shale gas had typically higher
methane
(based on about 60 wells)

9. Definition of active versus non-active wells:
Private wells located <1 km from a shale gas had typically higher
methane
Lockheaven Fm
Catskill Fm
(based on 91 wells)

10. Methane sources?
Non-active
A distinction between active
Active wells with a thermogenic
isotopic fingerprint and non-
active wells with a mixed
composition
Non-active
Active

11. Methane sources ?
Biogenic
Thermogenic

12. Methane sources?
Thermogenic
source

13. Possible mechanisms for leakage of stay gas to
water resources
Leakage of pressurized gas
through uncompleted casing to
shallow fracture systems
Migration from target formation via
fracture system (could be enhanced
by fracturing)
Figure from Scientific American Magazine, Nov 2011

14. Possible mechanisms for leakage of stay
gas to water resources
From Penoyer, (2011), Natural Resource Stewardship & Science

15. No apparent chemical contamination: no differences between
active to non active wells

16. No apparent isotopic differences between active to non active
wells

17. Results of the study indicate:
1. High methane concentration in active wells (<1 km from gas
well) are associated with a distinguish chemical and isotopic
composition identical to the Marcellus gas in production wells
while wells located >1 km had lower methane and different
composition;
2. Active wells were not contaminated by chemicals derived
from contamination of produced waters.

18. Occurrence of saline groundwater enriched in
barium in shallow aquifers
Warner, et al., Geochemical evidence for natural migration of Marcellus-like brine to shallow
drinking water in Pennsylvania, submitted to PNAS)

19. 100000 10,000.00
Appalachian Brines Appalachian (Ordovician
(Ordovician Silurian and Silurian and Devonian)
1,000.00
10000 Devonian) Brines
100.00 Type D Water
1000
Na (mg/L)
Br (mg/L)
10.00 Mixing Line
Mixing Line 1.00
100
0.10
10
0.01
Type C Water
1 0.00
1 10 100 1000 10000 1000001000000 1 10 100 1,000 10,000 100,000
1,000,000
Cl (mg/L) Cl (mg/L)
100,000,000 10,000,000
Marcellus Marcellus
10,000,000 Brines 1,000,000 Brines
1,000,000 Mixing Line
100,000
100,000 Mixing Line
Ba (ug/L)
Sr (ug/L)
10,000
10,000
Upper
Upper 1,000 Devonian
1,000 Devonian Brines
Brines
100 100
10 10
1
1
1 10 100 1,000 10,000 100,000 1,000,000
1 10 100 1,000 10,000 100,000 1,000,000
Cl (mg/L)
Cl (mg/L)

20. The strontium isotope fingerprint of the Appalachian brines

21. The strontium isotope fingerprint of the Marcellus brines

22. Hydrological connectivity between shallow
aquifers and deep Marcellus brine
Deep water displacement

23. Does produced water disposal cause long-
term ecological effects and health risks ?

24. Flowback from the Marcellus gas well: formation water
Frack water
Frack water
Days (after fracking)

25. Management of produced water
• Inject underground through a disposal well (onsite or
offsite),
• Discharge to a nearby surface water body,
• Haul to a municipal wastewater treatment plant,
• Haul to a commercial industrial wastewater treatment
facility,
• Reuse for a future fracking job either with or without
treatment.

26. Deep well injection
In 2009 about 140 million gallon were injected in Ohio;
In 2011 a significant increase; nearly 50% is coming from PA
where PA last May banned shipment of drilling waste to its sewage
treatment plants. Ohio 181 injection wells were in full capacity.
Trigger for earthquakes ? (Oklahoma, 5.6R; Arkansas
4.7R;Youngstown, Ohio 2.7R; 4.0R (12/31/2011)

28. Source: Cidney Christie, Duke

29. The effects of brine disposal: (preliminary results)
High salinity in the river water
(up to 500m downstream)
background
background

30. The effects of brine disposal: (preliminary results)
High bromide in the river water
(up to 500 m downstream)
•Long-term salinization of fresh water
resources: high chloride and bromide in
surface water enhance the formation of
carcinogenic disinfection by-products
(e.g., trihalomethane, bromodichloromethan
e) in potable water.
background
background

31. The effects of brine disposal: (preliminary results)
High barium in the river water
(up to 500 m downstream)
background

32. The effects of brine disposal: (preliminary results)
Accumulation of radionuclides in
river sediments (up to 300m
downstream); implications for long-
term radium bioaccumulation.
background

33. The take-home messages of this talk:
• Shale gas exploitation through hydro-fracturing may save America
from foreign oil but seems to cause methane contamination in shallow
drinking water wells in the Appalachian Basin.
•No evidence has shown, so far, for direct groundwater contamination
from produced/flowback water; yet new data show possible hydraulic
connectivity between the Marcellus and shallow aquifers in PA.
• Disposal of produced water from gas exploration directly into surface
water poses a significant risks to the ecological systems and waterways
in Pennsylvania.
• Sustainable and long-term shale gas developments will need to
accommodate the environmental issues associated with shale gas
drilling and hydro-fracturing.

34. Further reading:
Osborn, S., Vengosh, A. Warner, N. Jackson, R. (2011). Methane
contamination of drinking water accompanying gas drilling and
hydro-fracking. Proceedings of the National Academy of
Sciences, 108, 8172-8176.
Acknowledgements:
• FrankStanback, North Carolina
• National Science Foundation, Geobiology & Low-Temperature
Geochemistry Program
• Nicholas School of Environment, Duke University

35. Further information:
http://sites.nicholas.duke.edu/avnervengosh/
NSF Workshop at Duke (January 9, 2011): Environmental
and Social Implications of Hydraulic Fracturing and Gas
Drilling in the United States: An Integrative Workshop for the
Evaluation of the State of Science and Policy
http://www.nicholas.duke.edu/hydrofrackingworkshop2012/
workshop