Water is an essential component of deep shale gas development during both the drilling and hydraulic fracturing, or fracing, processes. Chesapeake uses water for drilling, where a mixture of clay and water is used to carry rock cuttings to the surface, as well as to cool and lubricate the drillbit. Drilling a typical Chesapeake deep shale gas well requires between 65,000 and 600,000 gallons of water. Water is also used in fracing where a mixture of water and sand is injected into the deep shale at a high pressure to create small cracks in the rock allowing gas to freely flow to the surface. Fracing a typical Chesapeake horizontal deep shale gas well requires an average of 4.5 million gallons per well.
Chesapeake utilizes several sources of water in deep shale gas exploration including rivers, creeks, lakes, discharge water from industrial or city wastewater treatment plants, groundwater and the re-use of fracturing water. The company often works directly with local officials to arrange water purchases from a municipality when drilling inside city limits. This water is typically transported via temporary pipelines or trucked to drilling locations for storage prior to use in tanks or impoundments. The overall mix of water sources used depends on the region and the availability of sources near drilling sites.
The natural gas industry is expected to increase total water usage by less than 1.5% in each shale gas area, and is well within available resources in the region. The largest water users are municipalities (public water supply), power generation, industrial users and agriculture. However, the magnitude of these uses varies widely from region to region. For example, in the Barnett Shale area of Texas, municipal uses account for more than 80% of water use, with agriculture accounting for about 8%. In the Marcellus Shale area of the Appalachian Basin, power generation accounts for more than 70% of water consumption, while agriculture accounts for approximately one tenth of one percent (0.10%). Water used in Chesapeake 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. Other water users typically consume water for years, decades or even longer.
How Much Is Five Million Gallons?
The five million gallons of water needed to drill and fracture a typical deep shale gas well is equivalent to the amount of water consumed by:
- New York City in approximately seven minutes
- A 1,000 megawatt coal-fired power plant in 12 hours
- A golf course in 25 days
- 7.5 acres of corn in a season
While these represent continuing consumption, the water used for a gas well is a one-time use.