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Shale Gas – The Energy-Water Nexus
Christopher HartoArgonne National Laboratory
2011 AWRA Spring Specialty Conference Baltimore, MD April 18‐20, 2011
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Acknowledgments
DOE‐ Office of Fossil Energy DOE – Office of Policy and International Affairs NETL‐ Strategic Center for Natural Gas and Oil RPSEA (Research Partnership to Secure Energy for America)
– Environmentally Friendly Drilling Program
John Veil – ANL (retired), Veil Environmental
Intro to Shale Gas
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Source: EIA
Shale Gas Plays The most active U.S. shale plays
to date are:– the Barnett Shale in Texas,– the Fayetteville Shale in
Arkansas, – the Antrim Shale in Michigan, – the Haynesville Shale in
Louisiana, – the Marcellus Shale in
Pennsylvania, New York, and West Virginia, and
– the Woodford Shale in Oklahoma
Two important Canadian shale plays:– the Horn River Shale in British
Columbia, and– the Montney Shale in British
Columbia and Alberta Source: DOE/EIA website
Supply Projections
Source: DOE/EIA Annual Energy Outlook 2011
Steps in the Shale Gas Process
Gaining Access to the Gas (Leasing)
Searching for Natural Gas
Preparing a SiteDrilling the WellPreparing a Well for Production (Hydraulic Fracturing)
Gas Production and Water ManagementMoving Natural Gas to Market
Well Closure and Reclamation
Steps involving water are shaded
Source: Fayetteville Shale Information website
http://lingo.cast.uark.edu/LINGOPUBLIC/index.htm
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Water Issues in Site Preparation
Need to consider stormwater runoff from all land areas disturbed during construction– Follow proper sediment control practices– Stabilize exposed surfaces
Different operators follow different degrees of storm water management practices
Water Issues in Drilling
Water is needed to make up drilling fluids– Ranges from 1 MG in the Haynesville
Shale to 60,000 gallons in the Fayetteville Shale
– Depends on the types of drilling fluids used and the depth and horizontal extent of the wells
Drilling waste is sent to lined pits or into a closed‐loop system employing tanks
Proper drilling practices required when drilling through the drinking water zones
Proper well construction and cementing to prevent migration of fluids around the well bore
Water Needed for Hydraulic Fracturing A single well may require 1 to 5 million gallons
– Individual volume is not critical, but collectively can be important within a region
– Depends on, formation properties, number of stages, length of lateral
Source of water:– Stream, river, or lake– Well– Impoundment created by producer– Public water supply
Piped to site vs. delivery in tank trucks
Frac Job Pumps Large Volume of Water, Sand, and Chemical Additives into the Well in Stages
Controversy over Frac Chemicals
Hydraulic fracturing exempt from EPA regulation under Safe Drinking Water Act Companies do not have to disclose the chemical additives in their frac fluids
– Some states now requiring disclosure and others considering it (WY the first)– Some companies voluntarily providing the information (Range Resources)
Legislation has been introduced in congress to remove exemption and require chemical disclosure
EPA embarking on a multi‐year study to evaluate the potential impacts of hydraulic fracturing on water resources
No known incidents of frac chemicals migrating into drinking water underground Multiple incidents involving surface water contamination due to spills Multiple events of natural gas migration into groundwater due to poorly
cemented wells (NOT due to hydraulic fracturing)– State of PA has updated well construction standards in response
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Management of Frac Flowback Water (1) Large volume of flowback returns to the surface in first few hours to few days
– Typically collect in lined pits/ponds
Management of Frac Flowback Water (2)
Some larger sites collect flowback in brine tanks Filtered and reused in
frac fluid for future well
Over time, smaller volume of produced water flows to surface– Collected in onsite tanks
Management of Frac Flowback Water (3) Collected water must be removed from site Typically is collected by tank trucks and hauled
offsite to:– Commercial UIC injection wells– Wastewater treatment plants– Evaporation ponds– Treatment and reuse facilities (orange tanks on
previous slide)
Producers may install their own injection wells or reuse the flowback water for future frac jobs– Recycling increasingly popular due to high cost
of water management
Potential Water Demand In Marcellus Shale Region
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State Hypothetical Maximum Number of Wells Drilled in a Year
Annual Volume under Scenario 1: 1 MGa of water needed per well
Annual Volume under Scenario 2: 2.8 MG of water needed per well
Annual Volume under Scenario 3: 3.9 MG of water needed per well
Annual Volume under Scenario 4: 5 MG of water needed per well
PA 1,669 1,669 MG 4,673 MG 6,509 MG 8,345 MGWV 293 293 MG 820 MG 1,142 MG 1,465 MGNY 293 293 MG 820 MG 1,142 MG 1,465 MGTotal 2,255 2,255 MG 6,314 MG 8,795 MG 11,275 MG
a MG = million gallons
Volume (Million gallons per day)
Water Required for Shale Gas Production Compared to Total Withdrawal (%)
Water needed for shale gas
6.2 ‐ 31 ‐
Total water withdrawal 24,577 0.03 – 0.13
Comparison of Water Needed for Shale Gas / Total Existing Water Withdrawals
Cumulative Regional Estimate of Water Needs under Hypothetical Maximum Drilling and Different Volume Scenarios
A word on greenhouse gas emissions
Many groups are pushing natural gas as a cleaner bridge fuel to displace coal– Emissions from combustion ~500 g/kWh vs. over 1000 g/kWh for coal
Growing controversy over lifecycle GHG emissions of natural gas due to fugitive methane emissions– Methane 21 to 25 times as potent as CO2
EPA Report ‐ http://www.epa.gov/climatechange/emissions/downloads10/Subpart‐W_TSD.pdf
– Previous work underestimated fugitive methane emissions– Emissions from shale gas higher than conventional gas
Cornell Study ‐ http://www.eeb.cornell.edu/howarth/Howarth%20et%20al%20%202011.pdf
– When fugitive emissions included, natural gas may be worse than coal– Based on limited data– The way data presented may skew conclusions, but fugitives still likely to add
significantly to natural gas GHG footprint
Conclusions– More study needed, better hard data– Engineering solutions available to reduce emissions with proper incentives
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Final Thoughts
Shale gas represents a large potential resource for domestic natural gas It must however be produced in a manner that protects both the environment and
human health Production of shale gas is more challenging than conventional gas
– Requires more Fresh water– Produces more waste water
All risks from hydraulic fracturing are not fully understood– Analysis to date appears to show that risks are manageable– Most incidents to date have been preventable
Industry has a responsibility to continue to actively engage stakeholders and work to improve their environmental performance.
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