Spreadsheets for Geothermal Water and Gas Geochemistry

Two Excel spreadsheets released with this paper support many of the common graphical analyses of water and gas chemistry used to interpret hot spring, fumarole and well samples in geothermal exploration and development. Cross-plots and ternary diagrams are generated from measured concentrations of chemical species using formulas based on equilibrium reactions and empirical relationships. Typical applications include geothermometry, fluid and gas space and time trend characterization, and data quality assessment. The spreadsheets provide charting capability compatible with all versions of Excel from 1997 to 2007. Liquid_Analysis_v1_Powell-2010-StanfordGW.xls takes tabulated water chemistry data input in ppm weight and stable isotope data in per mil and tabulates geothermometers and quality assurance parameters. Explanations for the calculations are referenced. Charts include the ubiquitous Giggenbach Na-K-Mg geothermometer ternary, three temperature "geoindicator" cross-plots, δO-δD, Cl-enthalpy, and four commonly used trace element ternary plots. Brief outlines of applications reference publications that provide more detailed case histories. Gas_Analysis_v1_Powell-2010-StanfordGW.xls takes gas analyses from steam samples in a variety of commonly reported units, makes an air correction (if needed) and plots four common ternaries, three3 “YT” gas geothermometer grids and two gas ratio geothermometer grids, mainly derived from the work of Werner Giggenbach. Typical applications of the graphical analyses provided in this gas spreadsheet are briefly summarized based on an earlier paper. These spreadsheets are offered as freeware, without warranty of fitness for any purpose under the GNU General Public License 3, subject to users’ reference to this paper in initial publications of work based on these spreadsheets.