Capillary tension and imbibition sequester frack fluid in Marcellus gas shale

In a recent issue of PNAS, Warner et al. (1) interpreted local ground water chemistry in the Appalachian Basin as a signal for cross-formational pathways where natural migration of brine from the deep formations may be ongoing today. The implication of this paper is that the Marcellus is leaking now naturally, without any human assistance, and that if water-based fluid is injected into these cross-formational pathways, that leakage, which is already “contaminating” the aquifers with salt, could be made much worse.