Water Quality Issues Associated
with Shale-Gas Development
Jim Saiers
Professor of Hydrology and Associate Dean of Academic Affairs
Yale School of Forestry & Environmental Studies
Resources for the Future Conference on Managing the Risks of Shale Gas
14 November 2011
Stages of Shale-Gas Development
Mineral Leasing
Permitting
Site Preparation
Gas-Well Drilling and Casing
Hydraulic Fracturing
Gas-Well Production
Gas-Well Plugging and Abandonment
How might these
processes affect
freshwater quality?
Stages of Shale-Gas Development
Mineral Leasing
Permitting
Site Preparation
Gas-Well Drilling and Casing
Hydraulic Fracturing
Gas-Well Production
Gas-Well Plugging and Abandonment
Site Preparation and Land Disturbance
Michaels et at., 2010
www.ithacajournal.com
Average Spatial Disturbance
for Site Preparation1
Well-pad areas
3.1 acres
Associated infrastructure
5.7 acres
Total
8.8 acres
www.democracyinaction.org
1Johnson,
2010
Land-Cover Classes Disturbed
Through Shale-Gas Site Preparation
Cucura et al., 2011
Site Preparation, Land Disturbance, and
Stream-Water Quality
 Forest clearing and excavation for site
preparation leaves soils unprotected
leading to land-surface erosion
 Eroded soil and soil-bound contaminants
are carried to streams and impair water
quality
Soil Erosion and Stream-Water Quality:
Considerations and Mitigative Measures
 Landscape recovery from erosion-inducing disturbances can be rapid
 Erosion control is part of regulatory requirements for site preparation
Stages of Shale-Gas Development
Mineral Leasing
Permitting
Site Preparation
Gas-Well Drilling and Casing
Hydraulic Fracturing
Gas-Well Production
Gas-Well Plugging and Abandonment
A Shale-Gas Well
Al Granberg
Gas-Well Drilling and Casing
“Top-Hole” Drilling with Air-Rotary Rig
Setting the Surface Casing
“Big Rig” for Horizontal Drilling
Big Rig for
Horizontal Drilling
“top holes” yet to be completed
Gas-Well Drilling and Potential Mechanisms of
Groundwater Contamination
 Drilling fluids are used during gas-well
drilling
Drilling-fluid additives have, in at least one
case, entered shallow groundwaters
 AirFoam HB, a surfactant, migrated via groundwater
pathways from a Marcellus wellbore to a nearby spring
 Post-drilling increases in bromide levels within 5 of 16
drinking-water wells (Boyer et al., 2011)
 Instances of groundwater contamination caused
by the gas-well drilling process appear to be rare
SunGazette.com
Stages of Shale-Gas Development
Mineral Leasing
Permitting
Site Preparation
Gas-Well Drilling and Casing
Hydraulic Fracturing
Gas-Well Production
Gas-Well Plugging and Abandonment
The Marcellus Shale Close Up
Photo by M. Wirtz
1 mile
Occurrence of the Marcellus Shale
drinking-water
wells
Hydraulic Fracturing
Al Granberg
Hydraulic Fracturing Operations
near Mansfield, PA
Plumbing for Frac-Water
Injection
12
Freshwater Storage for Hydraulic Fracturing
Frac-Water: From Cradle to Grave
Stream water
Water tanker trucks
Surface storage at
gas-well site
Add:
sand, biocides,
scale inhibitors,
acids, surfactants
Flowback treatment
“flowback”
water
Deep-well
Injection
brine
Potential Mechanisms of Freshwater Contamination
by Hydraulic Fracturing
 Surface spills of frac water & flow-back
 during tanker-truck transport
 accidental releases at drill sites
fractures
migration path
 natural fractures as conduits
old gas well
 abandoned gas wells as conduits
≈1 mile
 Chemical migration from frac zone
aquifer
Marcellus
Stages of Shale-Gas Development
Mineral Leasing
Permitting
Site Preparation
Gas-Well Drilling and Casing
Hydraulic Fracturing
Gas-Well Production
Gas-Well Plugging and Abandonment
 Improperly cased/cemented shale-gas wells
allow methane (CH4) escape into aquifers
drinking-water
aquifer
Gas-Well Production and Methane
Contamination of Groundwater
CH4
 The likelihood of CH4 leakage is poorly quantified
 Standard methods for well construction are
intended to minimize probability of methane release
Marcellus
Methane in Drinking Water
and Underground
 Is methane harmful?
 Methane is non-toxic and non-caustic
 Accumulation of methane gas in enclosed spaces
(e.g., water-well casings) can lead to explosion
Methane in Drinking-Water Aquifers
of the Marcellus Region
 Methane was present in drinking-water aquifers prior to
shale-gas development:
 49 of 91 water wells sampled within Tioga County in 2004-20051
 24% of 189 water wells sampled in northeast and southeast PA2
 Methane contamination of drinking-water aquifers can also occur from
 abandoned gas wells from old drilling operations
 underground coal mining
 subsurface gas-storage reservoirs
 native shallow gas
unrelated to
shale-gas
development
1Breen
et al., 2005
2Boyer et al., 2011
Site Preparation
Gas-Well Drilling and Casing
Hydraulic Fracturing
Gas-Well Production