Produced water
Produced water is a term used in the oil industry to describe water that is produced along with the oil
Petroleum or crude oil is a naturally occurring, flammable liquid consisting of a complex mixture of hydrocarbons of various molecular weights and other liquid organic compounds, that are found in geologic formations beneath the Earth's surface. Petroleum is recovered mostly through oil drilling...

 and gas
Natural gas
Natural gas is a naturally occurring gas mixture consisting primarily of methane, typically with 0–20% higher hydrocarbons . It is found associated with other hydrocarbon fuel, in coal beds, as methane clathrates, and is an important fuel source and a major feedstock for fertilizers.Most natural...

. Oil and gas reservoirs have a natural water layer (formation water) that lies under the hydrocarbons. 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
Water injection (oil production)
Water injection refers to the method in oil industry where water is injected back into the reservoir, usually to increase pressure and thereby stimulate production. Water injection wells can be found both on- and offshore, to increase oil recovery from an existing reservoir...

 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.

Historically, produced water was disposed of in large evaporation ponds, however this has become an increasingly unacceptable disposal method from both environmental and social perspectives. Produced water is considered an industrial waste and Coal Seam Gas (CSG) producers are now required to employ beneficial re-uses for produced water.

The broad management options for re-use are Direct Injection
Direct injection
Direct injection may refer to:*A music recording technique more commonly referred to as Direct Input*A method of fuel injection for an internal combustion engine, as in a gasoline direct injection petrol engines and most diesel engines...

, Environmentally acceptable direct-use of “untreated” water, or “Treatment” to a standard defined by the Environmental Protection Agency (EPA) before disposal or supply to users.
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