“JustBeneaththeSurfaceWV.com” is a web-site of the natural gas industry which has posted a slide presentation entitled Water Management and Marcellus Gas Development, by Paul Ziemkiewicz, PhD, Director, West Virginia Water Research Institute.  This covers the topics of water management including withdrawals, the management of returned frac water, produced water, disposal options and the effects on streams.

It is reported that the amount of Frac return water is ~10 to 20% of the amount injected. After 7 -10 days flow back is greatly reduced and is considered produced water.  Flow-back rates during first 7 –14 days may average 3,000 -5,000 barrels/day, declining rapidly to a few 100 bbl/day. Further decline is gradual, 10 to 20 b/day, after a few months. 

The total dissolved solids level in frac water is usually under 120,000 parts per million.  This sometimes contains  acrylamide copolymer, also known as polyacrylamide which has been reported to contain small concentrations of acrylamide (which is toxic). Sulfate is normally added to precipitate insoluble BaSO4 and SrSO4.  Radium salts can also be rendered insoluble as radium sulfate.

CONCLUSIONS Regarding Returned Frac Fluid:

Chemistry: Generally neutral to alkaline; Primarily sodium, calcium, chloride (about 95% of TDS); Magnesium, strontium and barium in lesser amounts; Volatile/non-volatile organic compounds in varying concentrations

Environmental/health and safety: Primary environmental issue: salinity; Primary human health issue: organics; ‘You don’t want to drink fracing fluid’

Management: Water managers must keep it out of streams and drinking water supplies; Treatment-STPs, Evaporation, deep well injection; Recycling