Abstract

Chemical and isotopic characteristics of selected inorganic constituents are reported for brines from the Berea Sandstone of Mississippian age, the "Clinton" sandstone (drillers term) in the Albion Sandstone of Silurian age, and the Rose Run sandstone (informal term) in the equivalent of the Knox Dolomite of Cambrian and Ordovician age in 24 counties in eastern Ohio.

Ionic concentrations of dissolved constituents in brine from the three sandstones generally fall in the following ranges: (in millimoles per kilogram of brine): Na, Cl > 1,000; 100 > Ca, Mg <1,000; 1 > K, Br, Sr, Li, Fe, SO₄ <100; Mn, Zn, Al, I, HCO₃, SiO₂ <1. Mean ionic concentrations of Ca, Mg, Na, Cl, K, S0₄, and Br, and mean values of density and dissolved solids are significantly different at the 95-percent confidence level in each sandstone. Only potassium has a unique concentration range in each sandstone (millimoles per kilogram): 0.3 - 12 (Berea), 13 - 57 ("Clinton"), and 81 - 92 (Rose Run).

For applications involving brine contamination, selected concentration ratios are identified as potential indicators for geochemical tracing of brines having some history of dilution. The K:Na ratios work best for identifying the source sandstone of an unidentified brine. These ranges are K:Na, 0.0002 - 0.0185 (Berea); 0.0073 - 0.0238 ("Clinton"); 0.0230 - 0.0462 (Rose Run). Other constituent ratios may prove useful for differentiating one brine from the other two. "Clinton" and Rose Run brines have no statistical difference in mean values for Ca:Mg, Na:Ca, Na:Cl, Mg:K, Ca:K, Cl:Ca, Mg:Br, and Na:Br. These ratios, in combination with K:Br and Cl:Br, may be used to identify Berea brines.

With respect to isotopic characteristics of hydrogen, oxygen, and sulfate sulfur, a moderate range of _δD (-48.0 to -13.5 permil) and _δ¹⁸O (-5.45 to -1.25 permil) indicate a meteoric water origin for the water matrix in Ohio brines. _δD and _δ¹⁸O values are not useful for differentiating brines from the three formations. The _δ³⁴S (SO₄^2-) values for Ohio brines range between +4.6 to +28.4 permil. The heaviest sulfate sulfur is in brine from the Cambrian and Ordovician Rose Run sandstone. A single Berea brine sample was determined to have the lightest _δ³⁴S (SO₄^2-) value. "Clinton" brines have _δ³⁴S (SO₄^2-) intermediate between those of the Rose Run and Berea sandstones. Sulfur isotopes may have utility for differentiating the isotopically heavy sulfate found in brines from the isotopically light sulfate found in oxidizing ground water.

First posted December 10, 2010

Revised September 18, 2013