Production
from the Marcellus gas shale generated international interest when methane
accumulated in the surface housing of a water well pump and exploded. The Pennsylvania Department of Environmental
Protection (PA-DEP) immediately investigated and determined the cement had
insufficiently isolated shallow methane-bearing sands (not the Marcellus gas
shale) and methane from these sands was leaking into ground water.
Production
from the Marcellus gas shale generated international interest when methane
accumulated in the surface housing of a water well pump and exploded. The Pennsylvania Department of Environmental
Protection (PA-DEP) immediately investigated and determined the cement had
insufficiently isolated shallow methane-bearing sands (not the Marcellus gas
shale) and methane from these sands was leaking into ground water. The media immediately seized upon the story
and painted a picture of an industry unable to manage risk. The reputation of gas shale was further
darkened by a Hollywood polemic called, Gasland, a documentary based loosely on
facts. Later there were two highly
publicized blowouts from Marcellus wells and some surface spills that added
strength to those who argued against industry.
The biggest public fear was the frack fluid could, somehow, flow uphill
more than 2000 meters to contaminate groundwater. Of course, there are a number of physical
laws such as the law of gravity and the law of buoyancy that prevent this from
happening. Since the initial hype by the
media, studies by both the US Environmental Protection Agency (EPA) and PA-DEP
have shown beyond a shadow of a doubt that no frack fluids have contaminated
groundwater in the vicinity of the methane leaking from casing. Microseismic surveys have since shown that
fracture stimulations travel laterally as much 300 m but are generally
restricted in vertical growth to 100 m.
The
focus of the fracking debate has since shifted to overlap with the climate
debate. The debate was further sharpened
by academic studies claiming such a high rate of methane leakage during
completion that the effect on global warming would be substantial even though
burning methane releases about half the CO2 relative to that released by coal
on a BTU basis.