Produced water

From Wikimarcellus

Produced water is naturally occurring water found in the sedimentary shale beds traversed by the wellbore. It is generally very saline in nature and presents an environmental challenge for Marcellus shale drillers. Produced water requires proper treatment before disposal. It should not be confused with recovered fracturing fluid pumped down a well when it is hydro-fractured.

There is a point where the water that flows up a well shifts from being primarily recovered fracturing fluid to that of produced water. The dividing line can be difficult to discern, yet can be distinguished by comparing the different chemical signatures of the recovered frac fluid to that of the naturally-occurring shale formation water.

Produced water has very high salinity and total dissolved solids (TDS).

It picks up various minerals from the shale formation including barium, calcium, iron, magnesium and sulpher.

There are also dissolved hydrocarbons present in produced water.

Produced water may also include low levels of naturally occurring radioactive substances (NORM) such as radium.