Natural Gas Drilling and Natural Gas Drilling and Drinking WaterDrinking Water

By Matt CorteseMentor: 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

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

Source: AAPGN

Broome County: 390 mya and today

Source: Dr. Ron Blakey

U.S. Gas Shale Deposits Source: ALL Consulting

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 of drilling pads on the surface

• Horizontal drilling laterals can extend for up to a mile underground!

Marcellus Shale drill core from West Virginia, 3.5 inches in diameter, containing a calcite-filled vertical natural fracture.Source: Daniel Soeder, USGS

Drilling is oriented vertically until the shale is reached

Then well bore turns at depth of target formation

Source: Geology.com

Vertical natural fractures, called “joints” by

geologists, in Devonian shale. Source: Geology.com

Horizontal (left) and Vertical (right) well completions – note how the horizontal well crosses

more vertical fractures Source: ALL Consulting

Horizontal Vertical

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 gas-

bearing 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

Lined Fresh Water Supply Pit from the Marcellus Shale Development in PASource: ALL Consulting, 2008

Hydraulic Fracturing of a Marcellus Shale Well in West Virginia (notice yellow holding tanks)Source: Chesapeake Energy Corporation, 2008

Pipes for pumping fresh water to a “frac job”Source: AXPC

The Drilling Process: Hydraulic Fracturing

A fluid transport truck – used for transporting water or other additivesSource: FSMF Resources

• 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

The Drilling Process: Hydraulic Fracturing

A pumper truck (above) and acid truck (below) Source: Producers Service Corporation

• 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

• After acid treatment, a “slickwater pad,” of friction-reducing 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

• 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

The Drilling Process: Hydraulic FracturingSource: 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 requires significant amounts of waterwater and is conducted in proximity to valuable surface and ground water” – U.S. Dept. of Energy Shale Gas Primer, 2009

Water Usage:• Hydraulic fracturing: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

• Water treatment of flowback: many management plans call for disposal of fluids in municipal water treatment facilities that can’t handle the brine/radioactivity

Aerial view of the the heavily developed Jonah natural gas field, upper Green River valley, 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

Closed-loop drilling site in ColoradoPhoto credit: Dan Randolph

Water TestingSource: Community Science Institute

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