USING THE SHALENETWORK DATABASE TO UNDERSTAND PENNSYLVANIA WATER QUALITY IN AREAS OF HYDRAULIC FRACTURING OF MARCELLUS SHALE

Hydrofracturing is used to increase porosity in gas-containing shale formations at depth. Public controversy has developed in response to the use of hydrofracturing especially in the northeastern states underlain by the Marcellus shale where some citizens and scientists question whether gas recovery will contaminate local waters. Concern centers on contamination due to both the chemicals used in hydrofracking fluids or from solutes in the brines that are brought back to the surface during gas production. Researchers, government agencies, and citizen scientists in Pennsylvania are teaming up to run the ShaleNetwork (www.shalenetwork.org), an NSF-funded research collaboration network that is currently finding, collating, sharing, publishing, and exploring data related to water quality and quantity in areas that are exploiting shale gas. A team of scientists from Penn State, Dickinson College, and Pitt have spearheaded the database which is available through CUAHSI's HydroDesktop (www.shalenetwork.org). At Penn State, we are using the database to understand possible impacts from the shale gas industry. So far, we have discovered no evidence that large-scale regional water quality has been impacted in PA although the database shows the effects of some incidents. One interesting observation has emerged by comparing pristine PA water to well-derived waters. Specifically, the behavior of Sr and Ba are similar among samples from 3 water types: 1) porewaters within soils developed on Marcellus outcrops; 2) salt-containing springs; 3) flowback/production waters for Marcellus gas wells. We hypothesize that, although some components of flowback waters (Na, Ca, Cl) derive from subsurface brines controlled originally by evaporation of seawater, other components (Sr, Ba) may be signatures of ongoing shale-water mineral reactions. The similarities among soil, spring, and flowback waters could be explained if Sr and Ba are dissolved from minerals in the same ratio regardless of temperature. If this is true, then the soils developed on Marcellus shales at low temperature are an analog for some shale-water reactions in the subsurface. We are investigating this idea further by analyzing chemistry (bulk digestion), mineralogy (XRD), and porosity (neutron scattering) of Marcellus shale from the subsurface and outcrop.