AskChesapeake

How much water does the natural gas industry use in the Marcellus Shale?

Water is an essential component of Chesapeake’s deep shale gas development. Chesapeake uses water for drilling, where a mixture of clay and water is used to carry rock cuttings to the surface and to cool and lubricate the drillbit. Drilling a typical Chesapeake Marcellus Shale gas well requires approximately 100,000 gallons of water.

Water is also used in hydraulic fracturing, where a mixture of water, sand and other additives are pumped under high pressure into the deep shale to create small fissures, or fractures, in the rock which allow natural gas to flow. Hydraulically fracturing a typical Chesapeake Marcellus horizontal deep shale gas well requires an average of four million gallons. Normally, a hydraulic fracturing operation is only performed once during the life of a well. In comparison, New York City uses on average four million gallons of water every five minutes¹.

The volume of water necessary to drill and fracture Marcellus Shale wells represents a very small percentage of the total water resources used in the region. This region generally includes central and western Pennsylvania, southern New York and northern West Virginia. The total water used for all commercial and residential purposes in the Marcellus Shale area in 2000 was approximately 3.6 trillion gallons. The natural gas industry is expected to increase the amount used by less than 0.1%, which is well within the available resources in the region.* Again, this volume is very small in terms of the overall water budget for the region. The largest water users in the Marcellus Shale area are power generation (approximately 72%), industry and mining (approximately 16%) and municipal/public water supply (approximately 12%). Agricultural water use accounts for only one-tenth of one percent (0.10%) in this area. Water used in Chesapeake Marcellus deep shale gas differs most notably from all other uses because it is temporary, occurring only during the drilling and completion phases of each well. Use of this water does not represent a long-term commitment of the resource in the Marcellus Shale area.

* USGS Estimated Use of Water in US, County Level Data for 2000

Where does this water come from?

Chesapeake works collaboratively with regional, state and local agencies to ensure that water use for deep shale gas development is consistent with water use plans and does not adversely affect other users. Chesapeake utilizes a variety of water sources during Marcellus Shale gas exploration, including rivers, creeks and lakes. Chesapeake is reviewing the use of a variety of other water resources, such as treated discharge water from industrial or city wastewater treatment plants, groundwater and the re-use of fracturing water. When drilling inside city limits, Chesapeake often works directly with local officials to arrange water purchases from a municipality.

What is hydraulic fracturing?

Hydraulic fracturing, commonly referred to as fracing, is the process of creating small fissures, or fractures, in underground formations to allow natural gas to flow. Variables such as the surrounding rock formations and thickness of the targeted shale formation are studied by scientists before fracing is conducted. The result is a process that optimizes the network of fractures and keeps them safely contained within the boundaries of the deep shale gas formation.

In Chesapeake’s deep shale gas plays, water, sand and other additives are pumped under a high pressure into the formation to create small fractures. The fluid is over 99% water and sand, along with a small amount of special-purpose additives². The newly created fractures are “propped” open by the sand, which allows the natural gas to flow into the wellbore and be collected at the surface. Normally a fracing operation is only performed once in the life of a deep shale gas well.

What chemicals are used in fracing?

Approximately 99.5% or more of the fluid used during fracing consists of water and sand. Other typical ingredients and their corresponding concentrations include a friction reducer - -0.088%, gelling agent - 0.056%, and anti-bacterial agents - 0.001%. A list of a typical deep shale fracturing mixture is below³:

Fracturing Fluid Additives, Main Compounds and Common Uses

Additive Type	Main Compound	Purpose	Common Use of Main Compound
Acid	Hydrochloric acid or muriatic acid	Helps dissolve minerals and initiate cracks in the rock	Swimming pool chemical and cleaner
Antibacterial agent	Glutaraldehyde	Eliminates bacteria in the water that produce corrosive by-products	Disinfectant; Sterilizer for medical and dental equipment
Breaker	Ammonium persulfate	Allows a delayed break down of the gel	Used in haircoloring, as a disinfectant, and in the manufacture of common household plastics
Corrosion inhibitor	n,n-dimethyl formamide	Prevents the corrosion of the pipe	Used in pharmaceuticals, acrylic fibers and plastics
Crosslinker	Borate salts	Maintains fluid viscosity as temperature increases	Used in laundry detergents, hand soaps and cosmetics
Friction reducer	Petroleum distillate	“Slicks” the water to minimize friction	Used in cosmetics including hair, make-up, nail and skin products
Gel	Guar gum or hydroxyethyl cellulose	Thickens the water in order to suspend the sand	Thickener used in cosmetics, baked goods, ice cream, toothpaste, sauces, and salad dressings
Iron control	Citric acid	Prevents precipitation of metal oxides	Food additive; food and beverages; lemon juice ~7% citric acid
Clay stabilizer	Potassium chloride	Creates a brine carrier fluid	Used in low-sodium table salt substitute, medicines and IV fluids
Oxygen scavenger	Ammonium bisulfite	Removes oxygen from the water to protect the pipe from corrosion	Used in cosmetics, food and beverage processing and water treatment
pH adjusting agent	Sodium or potassium carbonate	Maintains the effectiveness of other components, such as crosslinkers	Used in laundry detergents, soap, water softener and dish washer detergents
Proppant	Silica, quartz sand	Allows the fractures to remain open so the gas can escape	Drinking water filtration, play sand, concrete and brick mortar
Scale inhibitor	Ethylene glycol	Prevents scale deposits in the pipe	Used in household cleansers, de-icer, paints and caulk
Surfactant	Isopropanol	Used to increase the viscosity of the fracture fluid	Used in glass cleaner, multi-surface cleansers, antiperspirant, deodorants and hair color

What is produced water?

Water naturally exists within the Marcellus Shale formation. Water that comes to the surface during flowback operations (frac fluid recovery) and with the natural gas during production operations is called “produced water.” Containing naturally occurring compounds such as salt, produced water can have more than five times the salt content of seawater and continues to flow throughout the life of the well. The flow of produced water diminishes significantly over time, with water output dropping to only a few barrels per day after the first month.

Sourcing Reference:

¹ New York Department of Environmental Protection - They list the average daily water consumption by year – “yesterday NYC “consumed” 1.03 billion gallons” – break this down as it relates to using approximately 3.5 million gallons in 5 minutes.

² US Department of Energy- “Modern Shale Gas Development in the United States. A Primer” – Page 61

³ US Department of Energy - “Modern Shale Gas Development in the United States. A Primer” – Page 63