Utica Shale Play Oil and Gas Brines: Geochemistry and Factors Influencing Wastewater Management

Abstract

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.

Kerogen nanoscale structure and CO2 adsorption in shale micropores

“…The Barnett shale produces both oil as well as dry gas while the Marcellus is primarily a dry gas play. The Utica shale is considered the major source rock in the Appalachian basin 35 and produces both oil and dry gas.…”

Machine Learning Can Assign Geologic Basin to Produced Water Samples Using Major Ion Geochemistry

“…In addition to developing training sets with data in the USGS PWGD, we also used recently published data (Blondes et al, 2020;Engle, 2019;Engle et al, 2020) that is not currently included in the USGS PWGD as additional testing data for the models. The data are produced waters from the Eagle Ford (n = 39; Engle, 2019;Engle et al, 2020) and the Appalachian Basin, specifically the Utica Shale and Clinton sandstone (n = 52; Blondes et al, 2020).…”

“…In addition to developing training sets with data in the USGS PWGD, we also used recently published data (Blondes et al, 2020;Engle, 2019;Engle et al, 2020) that is not currently included in the USGS PWGD as additional testing data for the models. The data are produced waters from the Eagle Ford (n = 39; Engle, 2019;Engle et al, 2020) and the Appalachian Basin, specifically the Utica Shale and Clinton sandstone (n = 52; Blondes et al, 2020). Because the data used in the validation sets may have originated from the same sampling campaigns as those data used in the training sets, i.e., both were from the same database, this may introduce bias into the TestPWGD7 and TestPWGD9 results.…”

“…The Random Forest ''extratrees'' model used on the unknown data (SI Table S4) predicted at 97% accuracy for the new Eagle Ford data, but only correctly classified 1.9% of the Appalachian produced water samples (see Supporting Information). Fifty-one of the 52 produced water samples that originated from the Appalachian basin (Blondes et al, 2020) were classified as Arkla waters. Only one sample from this 52 sample dataset was predicted to be from the Appalachian basin.…”

“…Many producing formations or basins across the continental USA produce waters that have been previously well characterized, such as the Appalachian Basin (Blondes et al, 2020;McDevitt et al, 2020;Osborn et al, 2012;Tasker et al, 2020), the Permian Basin (Engle et al, 2016;Nicot et al, 2020), the Denver Basin (Rosenblum et al, 2017), the Williston Basin (Iampen & Rostron, 2000;McMahon et al, 2020;Varonka et al, 2020), and the Gulf Coast (Engle et al, 2020;McIntosh et al, 2010;Nicot et al, 2018). Although these regions produce waters that are geochemically well understood, few studies have analyzed trends in produced water chemistry across multiple basins or the continental USA (Birkle et al, 2019;Kharaka et al, 2019;Scanlon et al, 2020).…”