Transcript The Possible Effects of Natural Gas Drilling Activities

Natural Gas Drilling and
Drinking Water
By Matt Cortese
Mentor: Mr. Ron Brink
Broome County Health Department
Goals and Objectives of the Internship
•
•
•
•
•
Develop an understanding of natural gas drilling technologies, including how they
work and potential consequences for human health in NYS and Broome County
Research hydraulic fracturing, including chemicals used in drilling fluids. This also
includes how they are used in the drilling process and public health implications
Digitize and update baseline data on groundwater quality in Broome County
Develop a comprehensive list of chemicals, from a range of independent sources,
and recommend water testing parameters for private and public water supplies
Review and understand the NYS DEC’s Supplemental Generic Environmental
Impact Statement (sGEIS) Final Draft on Hydraulic Fracturing and Horizontal Drilling
Natural gas well
drilling in Enfield, NY
Presentation Outline
• Natural gas drilling in New York State and
Broome County
• The drilling process in depth
– horizontal drilling and hydraulic
fracturing
• Public health risks and “worst practices”
• Results and Conclusions: Best practices,
data, and recommendations to protect
public health
– Drilling practices
– Baseline database for Broome County
– Water well testing parameter list
A Natural Gas Drilling Pad
Source: ALL Consulting
U.S. Gas Shale Deposits
Source: ALL Consulting
The Marcellus Shale
• The Marcellus shale is a Middle
Devonian-aged black shale deposit
(~390 million years old)
• It lies completely within the NE
United States and ranges from West
Virginia to southern New York State
•The Marcellus may be
the largest reserve of
natural gas in North
America (in its entirety)
• Recently, intense
interest from energy
companies with advent
of new technologies
•Like many shales, it
formed from decaying
organic matter at the
bottom of a shallow
inland sea
Broome County: 390 mya and today
Source: Dr. Ron Blakey
Source: NYS DEC
Gas Wells and the Millennium Pipeline in
Broome County
= Millennium Pipeline
The Drilling Process: Horizontal Drilling
• Horizontal drilling is a drilling technique where the well bore is turned
from a vertical drilling position to horizontal at the depth of the target
formation (such as the Marcellus) in order to improve production
• Hydraulic fracturing is often used with horizontal drilling (see diagram)
• Horizontal drilling increases productivity because the well bore comes
into contact with more natural gas-containing vertical fractures, which
allows more gas to travel to the well (see picture)
•
Horizontal wells require more
water than their vertical
counterparts, but can reduce
the number
Drilling
is oriented of drilling pads on
vertically
until the
the surface
shale is reached
• Horizontal drilling laterals can
Then
well bore
extend
for up to a mile
turns at depth of
underground!
target
formation
Vertical natural fractures, called “joints” by
geologists, in Devonian shale.
Source:
Geology.com
Source: Geology.com
Horizontal
Vertical
Marcellus Shale drill core from
West Virginia, 3.5 inches in
diameter, containing a calcitefilled vertical natural fracture.
Source: Daniel Soeder, USGS
Horizontal (left) and Vertical
(right) well completions – note
how the horizontal well crosses
more vertical fractures
Source: ALL Consulting
The Drilling Process: Hydraulic Fracturing
• Hydraulic fracturing is a drilling
technique where water and additives
are pumped under high pressure into a
completed well
• Used to blast open fractures in fossil
fuel-bearing rock (such as the
Marcellus)
– increases the permeability of the gasbearing rock by creating conductive
passages
– allows more gas to collect and flow to
the well through the fractures
• This process is nicknamed “fracking” or
“well-stimulation,” or a “frac job” by the
energy industry
• Hydraulic fracturing is one of the key
technologies that makes gas extraction
from impermeable shales cost-effective
The Drilling Process: Hydraulic Fracturing
• The hydraulic fracturing process is a complex, multi-stage process, which can be
broken down into several steps
• The first step in the hydraulic fracturing process is bringing in materials, mostly fresh
water, onto the drilling pad – this is done via a pipeline or tanker trucks.
• The water is then held in lined holding ponds or in steel containers for later use in the
multi-stage hydraulic fracturing operation
Pipes Fresh
Lined
for pumping
Water Supply
fresh water
Pit from
to a the
“frac job”
Source:
AXPC Shale Development in PA
Marcellus
Hydraulic Fracturing of a Marcellus Shale Well
in West Virginia (notice yellow holding tanks)
Source: ALL Consulting, 2008
Source: Chesapeake Energy Corporation, 2008
A fluid transport truck – used for
transporting water or other additives
Source: FSMF Resources
The Drilling Process: Hydraulic Fracturing
• While equipment and fluids for hydraulic fracturing are
brought onsite, the well is drilled and pressure tests of
pumping equipment are conducted.
• After tests are complete, an acid treatment is done in
order to clean the well bore of drilling mud and dissolve
certain rocks (like limestone)
– an acid treatment involves pumping concentrated
hydrochloric acid into the well
A pumper truck (above)
and acid truck (below)
Source: Producers Service Corporation
• After acid treatment, a “slickwater pad,” of frictionreducing agents is pumped into the well.
– This allows the “proppant” and other fluids to flow
more easily into fractures and helps to reduce pressure
– Typical friction-reducers are potassium chloride,
petroleum distillates, or polyacrylamide
• Other additives are also added to control “fouling” from
biological or chemical processes
– Biocides/slimicides are used for bacterial/slime
growth that can reduce well conductivity
– Scale inhibitors, corrosion inhibitors, and oxygen
scavengers are used for chemical fouling
A fracturing fluid
trailer Source: Donnan.com
The Drilling Process: Hydraulic Fracturing
•
After the slickwater pad and other additives are injected,
a series of “proppant stages” is initiated
– A proppant is a material used to “prop” open new
fractures to maintain fluid conductivity for the gas
– The proppant mixture is typically water, sand, and a
viscosifier called a “gellant”
•
The proppant stages do most of the rock fracturing
– As hydraulic pressure is increased, proppant and
gellant is forced into the newly formed cracks
•
A typical gellant is a complex carbohydrate that is
polymerized to form a reversibly viscous gel
– Gellants are typically composed of modified guar
gum (CMHPG) or modified cellulose (HEC)
– Can be polymerized in a pH-sensitive complex with
a metal ion (such as borate or zirconium)
– This system is used to help carry proppant further
into the induced fractures, and is useful because the
viscosity of the gellant is easily pH-controlled
– A chemical called a breaker (oxidizer or strong acid)
is used to lower the viscosity of the gel for extraction
Source: ProPublica
Sand truck delivering proppant
Source: Cudd Energy Services
What does natural gas drilling have to
do with
?
•
“Shale gas development both requires significant amounts of
water and is conducted in proximity to valuable surface and
ground water” – U.S. Dept. of Energy Shale Gas Primer, 2009
Water Usage:
• Hydraulic fracturing: requires the most water of any drilling
technique (up to 5 million gallons of fresh water from local
sources) and uses a variety of proprietary chemical additives
• Multi-well drilling pads and minimal pad spacing: heavy activity
(and thus demand for water) concentrated in one area
Water Quality:
• Additives: including acids, surfactants, scale/corrosion inhibitors,
biocides, proppants, gellants, breakers, and others are used in
hydraulic fracturing, many of which may present health hazards
• “Produced” water or “flowback”: water that is retrieved after
fracturing is extremely salty and may be radioactive
• Fluid recovery: it is not uncommon for as little as 10-15% of
injected fluid to be recovered
view of the the heavily
• Water treatment of flowback: many managementAerial
plans
call for
developed Jonah natural gas
disposal of fluids in municipal water treatment facilities
that can’t
field, upper Green River valley,
handle the brine/radioactivity
Wyoming, 2001
“Flowback” and Water Treatment
•
•
•
“Flowback,” also known as “produced water,” is the waste fluid that is returned to the
surface after hydraulic fracturing
Produced water contains fracturing fluids and formation waters (typically brines)
– These present potentially major health hazards if improperly managed or if
there are accidents, such as surface spills, natural disasters, leaks, etc.
– Brines are ubiquitous in flowback because of the marine origins of the shale
– Heavy metals and naturally-occurring radioactive materials (NORMs) may also
be present in flowback, posing further potential health risks
Produced water must be properly disposed of to prevent public health problems
– Many municipal wastewater treatment plants have been designated for disposing
of flowback, but are not equipped or designed to handle these fluids, particularly
because of high Total Dissolved Solids (from brine), NORMs, & other chemicals
– Underground injection is another option for disposal of “produced water,” but may
also create longer-term health risks
Flowback (left) to distilled water (right)
Source: 212 Resources
Copyright, 2008 The New York Times
“Worst Practices”
Public Health Best Practices and
Recommendations
• Baseline testing
– Testing of water wells before drilling begins is
essential for both liability purposes and health
reasons
• “Closed-loop” (pitless) drilling systems
– Flowback goes into steel tanks (not lined pits)
and is purified and recycled onsite
– Is much safer than pits since waste is handled
immediately and only solid waste is shipped
• Setback distances and secondary containment
– Setback distances are a buffer area between drilling sites
and surface water
– Secondary containment and spill detection methods, along
with setbacks, are important to mitigate contamination risk
• NYS DEC regulates drilling operations in NYS
– Supplemental Generic Environmental Impact Statement
sGEIS) in Final Review stages at present
Water Testing
Source: Community
Science Institute
Closed-loop drilling site in Colorado
Photo credit: Dan Randolph
Baseline Database
• I compiled and analyzed private water well data on inorganic contaminants
in water from groundwater tests, then updated GIS database (MapInfo)
• These records were made by groundwater engineers in Broome County,
and many dated as far back as the early 1970s
• This information can be used in the event that no other baseline water
quality data exists in cases of water contamination from gas drilling
• Finding GIS coordinates required extensive “detective work,” since some
places in the records only had a name and date as an identifier
Screen shot of MapInfo, the software
program I used to input chemical data.
Each dot in the map represents a data
point, with different colors representing
a different parameter