Produced water

Produced water refers to effluents that rise to the surface during energy drilling or extraction. This includes water naturally occurring alongside energy deposits, as well as water injected into the ground during hydraulic fracturing. Oil and gas reservoirs have a natural water layer (formation water) that lies under the hydrocarbons. Produced water can contain naturally occurring radioactive materials (NORM) and chemical additives used in drilling.

Background
Oil reservoirs frequently contain large volumes of water, while gas reservoirs tend to have smaller quantities. To achieve maximum oil recovery, additional water is often injected into the reservoirs to help force the oil to the surface. Both the formation water and the injected water are eventually produced along with the oil and therefore as the field becomes depleted the produced water content of the oil increases.

By 2010, the United States was creating 15-20 billion barrels of produced water each year. Worldwide, estimates top 50 billion barrels. According to the U.S. Department of Energy, for every barrel of oil produced globally, an average of three barrels of water are produced. In the United States, the water to oil / gas ratio (WOR) averages seven barrels of water to one of oil. In the worst cases, the WOR reaches 50 to 1. Energy companies pay between $3 – $12 to dispose of each barrel of produced water.

Waste re-use and disposal
Produced water is considered an industrial waste, although since 1988, all material resulting from the oil and gas drilling process is considered non-hazardous, regardless of its content or toxicity, making it subject to less strict regulatory standards.

The broad management options for re-use or disposal are injection into Class II disposal wells, "environmentally acceptable" direct-use of untreated water, or “treatment” to a government-issued standard before disposal or supply to users. In the United States these standards are issued by defined by the U.S. Environmental Protection Agency (EPA) for underground injection and discharges to surface waters.

Traditionally, produced water was evaporated in pits and then the dry dregs were trucked to landfills or designated dumping sites.

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External Articles

 * Lena Groeger, "What the Frack is in That Water?" ProPublica, accessed May 2012.