It goes back to huge task that the scientists have in trying to simplify complicated theories and Dr. Terry Engelder takes a good stab at it. In this case he uses Darcy’s Law to explain why Frac fluid will not migrate to the surface from the formation. I believe this issue was addressed in a previous post. I have yet to hear an anti-driller challenge Darcy’s Law and the imbibition of frac fluid in the Marcellus formation, yet I still hear about stray frac fluid working its way from below the surface through random cracks and fractures in the mile or so ground between the Marcellus and the groundwater. Darcy’s Law is also mentioned the NYSDEC sGEIS Page 6-53.
He then introduces another term: Meth-mud (short for methane mud). Meth-mud does not follow Darcy’s law so meth-mud can find its way into drinking water aquifers. Drilling releases meth-mud from shallower formations. This has happened once out of every 150 Marcellus wells drilled between 1/2008 and 8/2010. Not perfect, could be better. The NYSDEC in their study for the sGEIS introduced specific well designs and cementing expectations to avoid meth-mud impacts.
The act of hydraulic fracturing a well has NOT impacted groundwater from below. Meth-mud from the actual drilling of the well has impacted water.