The
Utica and Marcellus Shale Plays in the Appalachian Basin are
the fourth and first largest natural gas producing plays in the United
States, respectively. Hydrocarbon production generates large volumes
of brine (“produced water”) that must be disposed of,
treated, or reused. Though Marcellus brines have been studied extensively,
there are few studies from the Utica Shale Play. This study presents
new brine chemical analyses from 16 Utica Shale Play wells in Ohio
and Pennsylvania. Results from Na–Cl–Br systematics
and stable and radiogenic isotopes suggest that the Utica Shale Play
brines are likely residual pore water concentrated beyond halite saturation
during the formation of the Ordovician Beekmantown evaporative sequence.
The narrow range of chemistry for the Utica Shale Play produced waters
(e.g., total dissolved solids = 214–283 g/L) over both time
and space implies a consistent composition for disposal and reuse
planning. The amount of salt produced annually from the Utica Shale
Play is equivalent to 3.4% of the annual U.S. halite production. Utica
Shale Play brines have radium activities 580 times the EPA maximum
contaminant level and are supersaturated with respect to barite, indicating
the potential for surface and aqueous radium hazards if not properly
disposed of.