The Utica/Point Pleasant Shale (UPP) in the northeastern United States Appalachian Basin is one of the largest unconventional shale reservoirs in the world. While UPP development is extensive in Ohio and is increasing in Pennsylvania and West Virginia, there are no studies that report the chemistry of produced waters from UPP wells which could have important implications for understanding its origin, developing best management practices for handling and waste disposal, or identifying the fluid in the event of accidental spill events. Here, we document the elemental and isotopic chemistry of UPP produced waters from 26 mature wells (&gt;90 days of production) throughout Ohio, Pennsylvania, and West Virginia. Compared to the Marcellus and other conventional oil and gas (O&G) formations in the Appalachian Basin, UPP produced contained similar major elemental chemistry (i.e., Na, Ca, and Cl) but slightly higher activities of total radium (226Ra + 228Ra). UPP produced waters also had Sr/Ca molar ratios (0.04 to 0.25) and 87Sr/86Sr isotope ratios (0.7096 to 0.7123) that were similar to Marcellus produced waters but were distinct from conventional O&G produced waters. These Sr/Ca and 87Sr/86Sr ratios can be used to fingerprint small fractions (~0.1%) of UPP produced water in freshwater. However, in regions of the play where there is both Marcellus and UPP development, the similarities between the Marcellus and UPP produced waters make it challenging to distinguish these two fluids if they mix with freshwater.

Isotopic fingerprinting of produced water from Utica and Point Pleasant Shale

2019 Spring National Meeting

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