Presentation on theme: "Environmental implications of hydraulic fracturing and shale gas drilling in the United States Avner Vengosh Nicholas School of the Environment, Duke University."— Presentation transcript:
Environmental implications of hydraulic fracturing and shale gas drilling in the United States Avner Vengosh Nicholas School of the Environment, Duke University
Rob B. Jackson Nathaniel R. Warner* Stephen Osborn, Adrian Down Nicholas School of Environment Duke University
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, so far, for groundwater contamination from produced/flowback water. Disposal of produced water from shale gas wells 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.
Energy production in the USA (2009) EIA- US Energy Information Administration Total production= 73 quadrillion Btu
What is hydraulic fracturing (fracking)?
The critical role of shale gas production in the U.S.
Estimates of undeveloped technically recoverable shale gas and shale oil resources (total 750 trillion cubic feet) Source: IEA (2011)
Global shale gas basins
North America* Europe OECD Asia Pacific Latin America Africa Middle East 1000 TCF Conventional Unconventional Global Gas Resource Source: IEA; * Includes Europe Non OECD World: ~250 years coverage at current demand Large unconventional gains anticipated World Russia/Caspian*
Montrose, Susquehanna, Pennsylvania (June, 2011) Shale-gas drilling and hydro-fracturing
The Marcellus Shale, Appalachian Basin
Map Map of The Marcellus (red) and none-Marcellus (blue) wells drilled in Pennsylvania in 2010 (PA DEP) 1,386 gas and oil wells were drilled in PA in 2010
Major stages in shale gas production: Pad, impoundment and road construction; heavy truck traffic and heavy equipment; Drilling – drilling rigs require power from diesel engines; noise… Fracturing – during this stage, large amounts of water and fracturing fluid are pumped into the well to create fractures for the gas to escape from the shale; A portion of the fluid (30-40%; flowback) is returned into a wastewater impoundment where it is trucked for disposal/ treatment; once the well in operation – generation of produced water that need to be disposed; (from PA_DEP report on potential gas emission)
Major stages in shale gas production: Flaring –testing the gas well before production. Emissions are created from the burning of gas and atmospheric venting of non- combusted gas; Condensate Tanks – gas pumped from the well may contain brine and other volatile organic compounds that condense into collection tanks; Compressor stations – waw gas is piped from wells to compressor stations where the gas is pre-treated and compressed; building a network of gas pipes through the region. (from PA_DEP report on potential gas emission)
Key environmental risks associated with shale gas drilling and hydro-fracturing Methane contamination of drinking water wells Fugitive emissions of methane to the atmosphere Contamination by fracturing fluid (transportation, spills, disposal) Air pollution associated with different stages of gas production Disposal of fracturing fluids/produced water Health implications, quality of life (traffic, noise) Water use, lost (7-15 million liter per well) Water use, lost (7-15 million liter per well) Release of of fracturing fluid chemicals (spills, transportation)
What are the environmental risks associated with shale gas drilling and hydro-fracturing? Water Do we have enough 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?
Do we have enough water? Drilling – 230,000 to 3,780,000 liter per well; Fracking – 7.6 to 15.1 million liter per well 1400 wells per year, like in the Marcellus Shale, means million cubic meter per year (Durham, NC consumes MCM/year)
Figure from Scientific American Magazine, November 2011 Does shale gas drilling and hydro-fracking cause contamination of drinking water wells?
Duke Research activities (updated to August 2011): 1.Sampling over 200 shallow private wells in eastern PA, NY; 2. Sampling produced waters from several gas wells in PA and NY; 3. Analysis of methane in private wells – concentrations, isotopes ( 13 C CH4, 2 H CH4 ) 4. Analysis of the chemistry and isotopes of groundwater associated and not associated with gas wells in PA. 5. Analysis of the Marcellus Shale brines 6. Chemical (major and trace elements) and isotopic ( 87 Sr/ 86 Sr, 11 B/ 10 B, 18 O/ 16 O, 2 H/H) measurements. 7. Measurements of naturally occurring radium ( 226 Ra, 228 Ra) nuclides The research methods:
CH 4 13 C – 13 C/ 12 C 2 H – 2 H/H Isotopic fingerprinting of methane source
Proceedings of National Academy of Sciences, May 17, 2011
Duke research in Pennsylvania and New York
Hydro-geological cross section
Definition of active versus non-active wells: Private wells located <1km from a shale gas had typically higher methane (based on about 60 wells)
Definition of active versus non-active wells: Private wells located <1km from a shale gas had typically higher methane (based on 91 wells) Lockheaven Fm Catskill Fm
Methane sources? Active Non-active A distinction between active wells with a thermogenic isotopic fingerprint and non- active wells with a mixed composition
Thermogenic Biogenic Methane sources ?
Biogenic Dry thermogenic gas Methane sources ?
Possible mechanisms for leakage of stay gas to water resources Figure from Scientific American Magazine, Nov 2011
From Penoyer, (2011), Natural Resource Stewardship & Science Possible mechanisms for leakage of stay gas to water resources
No apparent chemical contamination: no differences between active to non active wells
No apparent isotopic differences between active to non active wells
Strontium isotopes: a sensitive tracer for mixing with produced/flowback water A lower 87 Sr/ 87 Sr for non-mixed fracturing fluids
The sensitivity of strontium isotopes to mixing with fracturing fluids and backflow brines Fracturing fluids-formation water mix
Boron isotopes: differentiation from other contaminant sources
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)
Possible hydraulic connectivity between deep Marcellus-like brine to shallow aquifers
Deep water displacement Can deep gas and brine in northeastern PA flow to the surface? Is it related to fracking ?
Results of the study indicate: 1.High methane concentration in active wells ( 1 km had lower methane and different composition; 2.Active wells were not contaminated by chemicals derived from contamination of produced waters.
Does produced water disposal cause long- term ecological effects and health risks ?
Whats in produced water? Salinity (Marcellus brine – 250,000 mg/L (10 fold seawater); High bromide, bromide presence in water enhances the formation of carcinogenic disinfection by-products (e.g., trihalomethane) upon chlorination of downstream potable water; High concentrations of toxic elements (barium, arsenic, selenium, lead); High concentrations of naturally occurring radioactive materials (NORMs); (5000 pCi/L, drinking water standard=5 pCi/L) Hydrocarbon residuals, oil, organics
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. Management of produced water
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) Deep well injection
Source: Cidney Christie, Duke
background High salinity in the river water (up to 500m downstream) The effects of brine disposal: (preliminary results) background
The effects of brine disposal: (preliminary results) High bromide in the river water (up to 500 m downstream) background 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, bromodichloromethane) in potable water.
The effects of brine disposal: (preliminary results) High barium in the river water (up to 500 m downstream) background
The effects of brine disposal: (preliminary results) background Accumulation of radionuclides in river sediments (up to 300m downstream); implications for long- term radium bioaccumulation.
A roadmap to clean energy Mountaintop coal mining streams contamination Installation of scrubbers to prevent air pollution (clean coal) enhances contaminants accumulation in coal combustion products water contamination Shale gas drilling and hydro-fracturing stray gas emission, methane contamination of shallow aquifers, produced water disposal
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, Acknowledgements: Frank Stanback, North Carolina National Science Foundation, Geobiology & Low-Temperature Geochemistry Program Nicholas School of Environment, Duke University
Further information: 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 workshop