U.S. Environmental Protection Agency Office of Resear ch and Development 1 

## HYDRAULIC FRACTURING RESEARCH STUDY

Why is EPA Studying Hydraulic Fracturing? Natural gas plays a key role in our nation’s clean energy future and hydraulic fracturing is one way of accessing this vital resource. Over the past few years, the use of h ydraulic fracturing for gas extraction has increased and has expanded over a wider diversity of geographic regions and geologic formations. It is projected that shale gas will comprise over 20% of the total U.S. gas supply by

2020. Given this expansion an d increasing concerns, EPA announced in March 2010 that it will study the potential adverse impact that hydraulic fracturing may have on drinking water.

EPA has sought advice regarding the potential scope of the study plan from EPA ’s Science Advisory Boa rd (SAB) Environmental Engineering Committe e, an independent, external federal advisory committee

. The SAB’s input will help ensure that a sound scientific approach is used to develop the study plan.

During this s ummer , EPA will conduct a series of

meetin gs to receive broad, balanced input on the study plan from stakeholders in key regions affected by hydraulic fracturing.

EPA will use the results from the study to help
evaluate potential risks associated with hydraulic fracturing in an effort to protect Ameri ca’s
communities and resources.

What is Hydraulic Fracturing? Hydraulic fracturing is a well stimulation process
used to maximize the extraction of underground

resources

– oil, natural gas and geothermal energy.
The hydraulic fracturing process inc ludes the acquisition of source water, well construction, well stimulation, and waste disposal. Hydraulic fracturing involves the pressurized injection of fluid s commonly made up of water and
chemical additives into a geologic formation . The

pressure exceeds the rock strength and the fluid opens or enlarges fractures in the rock

. As the formation is fractured, a “propping agent

, ” such as sand or ceramic beads, is pumped into the fractures to keep them from closing as the pumping pressure
is released. The f racturing fluids (water and chemical additives) are then returned back to the
surface . N atural gas will flow from pores and
fractures in the rock into the well for subsequent

extraction.

W ells used for hydraulic fracturing are drilled vertically, ve rtically and horizontally, or directionally (Figure 1 depicts vertical and horizontal drilling ).

W ell s may extend to depths greater than 8000 feet
or less than 1000 feet , and horizontal sections of a
well may extend several thousands of feet away
from th e production pad on the surface

.U.S. Environmental Protection Agency EPA/ 600 / F

- 10 / 002 June 2010 Office of Resear ch and Development 2 W hat is the Connection Between Water and Hydraulic Fracturing?

W ater is needed during the process, and it is a central component of the waste product s. Po tential impacts to drinking water supplies have been suggested from many recent reports.

Fracturing fluids can be up to 99 % water. The volume of water needed for hydraulic fracturing

var ies by site and type of formation. Fifty thousand to 350,000 gallons of water may be required to
fracture one well in a coalbed form ation while two to five million gallons of water may be necessary to
fracture one horizontal well in a shale formation. Water used for fracturing fluids is acquired from
surface water or groundwater in the local area.

Wastewaters from the hydraulic fract uring process may be disposed in several ways. For example, the
f lowback water following fracturing may be returned underground using a permitted underground injection well, discharged to surface waters after

treatment to remove contaminants

, or applied t o land surfaces . Not all fracturing fluids injected into the geologic formation during hydraulic fracturing
are recovered. Estimates of the fluids recovered range from 15

- 80% of the volume injected depending on the site. Some companies reuse
flowback to hydraulically fracture more than one well as a way of conserving water and recycling the
fluids

.

Public concerns have focused recently on the impacts of the hydraulic fracturing process used during natural gas production from shale and
coalbed methane fo rmations.

Potential risks to surface and underground sources of drinking water might occur at various points in the hydraulic fracturing process. The likelihood of those risks causing drinking water contamination will be evaluated during the EPA hydrau lic fracturing study. Contaminants of concern to drinking water include fracturing fluid chemicals and degradation products
and naturally occurring materials in the geologic
formation (e.g. metals, radionuclides) that are
mobilized and brought to the surf ace during the hydraulic fracturing process

.

REFERENCES:
http://www.epa.gov/ogwdw000/uic/wells_hydrofrac.html
http://www.epa.gov/safewater/uic/wells_coalbedmethanestudy.html

EPA is interested in receiving comments on the proposed hydraulic fracturing res earch study. Please submit your comments to EPA at hydraulic.fracturing@epa.gov, or
send written comments to Jill Dean, 1200 Pennsylvania Ave. NW, Mail code 4606M, Washington, DC 20460.