I'm glad the NYT ran the article since it expresses several concerns that I have. My background is hydrogeology/engineering geology and not necessarily petroleum geology, however I deal with the same rock properties and characterization issues likely to be faced by the gas reservoir engineers working on these formations.
The key factor is the effective porosity or the interconnected porosity. Shales may have a total porosity in excess or 50% however much of this porosity is totally isolated such that gas and liquids locked up in the clay matrix (shale is composed of clay minerals)is totally inextractable. The effective porosity may range from 0.5% to maybe 9%. From what I have read, the Marcellus shale eff. porosity tends to range around 4 to 5%. In my opinion, this is probably sufficient to maintain decent long term gas flow toward the fracture which was created by fracing if the reservoir pressures are maintained. Other formations might not possess as high of a effective porosity leading to high initial gas production but relatively rapid depletion.
The Marcellus is lower Devonian in age so it was subject to several orogenies (episodes of mtn building). This subjected the rock to considerable stress which likely caused microfractures which increased the effective porosity of the bedrock. the good news is that the stresses primarily propagate horizontally along planes of weakness in the shale. If they were to have propagated vertically, much of the gas would have been lost from the reservoir.
My guess is that the NYT concerns probably relate to formations where the effective porosity is low. Knowing human nature, I'm certain that some firms are overstating the reserves by overestimating the effective porosity. Wells in low eff porosity shale might produce well during the short run but the yield will taper off if the pores are not interconnected. Effective porosity less than 1% would probably result in rapid gas depletion since the gas migrating out of the rock matrix pores via molecular diffusion would be insufficient to support gas extraction. This would result in a well which would probably not be economically viable over the long term.
I'm certain that some of the recent surge in small drilling and exploration companies are under pressure to secure financing. The temptation to overstate effective porosity by a couple percent is probably too great to resist.
My advise is to follow the big players XOM, Chevron, COP since they have the reservoir engineers that are trained to look at this issue in depth.
FL
News 
Market Data 
Discover 
