Flowback water

From Wikimarcellus

'In the Marcellus shale, flowback water' (aka backflow water) from fracing natgas wells, that is, the fluid which returns to the surface (aka the frac load recovery), can be anywhere from 20-40% percent of the volume that is forced down a well. More than half of the frac water remains in the formation. At a certain point there is a transition between primarily recovering frac fluid to that of produced water. Usually this point is difficult to distinguish, yet may be discerned from the different chemical signatures of the frac water versus the naturally occurring water produced by the formation.

This flowback may be characterized as having high salinity and total dissolved solids (TDS). It is laden with the same fracing chemicals that were pumped into the well, in addition to any unique contaminants that are present in the rock formation water deep below.

The retuning fluid is generally collected in pits that are lined with plastic. The pit is then pumped dry, and the water is usually either recycled for fracing additional wells or else trucked off site to a waste water disposal facility. The Pennsylvania Department of Environmental Protection has formed a partnership with the oil and gas industry to research and develop innovative new methods of recycling and treating flowback water.

Municipal sewage disposal plants were never designed to handle flowback or produced water, yet existing and planned treatment facilities are believed to be adequate at least for the current level of Marcellus shale drilling in Pennsylvania.

A large percentage of flowback water is reused before it is released back into the environment. Roughly 60% gets reused, and this percentage is increasing. Industry leader Range Resources reuses 100% of its flowback water. All flowback water is either reused or treated by the industry.