A Computer Program for Multicomponent Geothermometry and Geochemical Speciation

geot-flowchartGeoT implements the multicomponent geothermometry method developed by Reed and Spycher (1984, Geochim. Cosmichim. Acta 46 513–528) into a stand-alone computer program (that is available for licensing), to ease the application of this method and to improve the prediction of geothermal reservoir temperatures using full and integrated chemical analyses of geothermal fluids. Reservoir temperatures are estimated from statistical analyses of mineral saturation indices computed as a function of temperature. The reconstruction of the deep geothermal fluid compositions, and geothermometry computations, are all implemented into the same computer program, allowing unknown or poorly constrained input parameters to be estimated by numerical optimization, either automatically using iGeoT (see below), or indirectly using external (separate) parameter estimation software, such as iTOUGH2, PEST, or UCODE. This integrated geothermometry approach presents advantages over classical geothermometers for fluids that have not fully equilibrated with reservoir minerals and/or that have been subject to processes such as dilution and gas loss.

The current GeoT and iGeoT versions allow for the reaction of selected minerals while making temperature estimations, for cases when some minerals (such as carbonates) are suspected to have reequilibrated with thermal fluids ascending to the surface. Another option is the iterative estimation of steam fraction (and correction for lost steam when making temperature estimations) by assuming iso-enthalpic boiling starting at the estimated reservoir temperature.

Most recently released: iGeoT V1.0. This software integrates GeoT with the parameter estimation engine of iTOUGH2. Therefore, with iGeoT, no separate parameter estimation software is required to estimate poorly known parameters necessary to re-construct the composition of deep fluids. The amount of dilution, steam fraction and composition of exsolved gas, and/or concentrations of solutes that may have been affected by re-equilibration can be automatically estimated by numerical optimization. iGeoT uses automatic parameter estimation techniques to estimate these unknown or uncertain input parameters. A nonlinear least-squares problem is solved, where the difference of multiple clustering measures from their optimal value is minimized by automatically adjusting the parameters of interest.

iGeoT can be run in forward mode just as GeoT without parameter estimation, or in two additional modes for parameter estimation, referred to as Automatic and Expert modes. In the automatic mode, the user only needs to identify the parameters that shall be estimated; iGeoT then automatically formulates the related inverse problem and solves it. In expert mode, the user is given the flexibility and power of all the features implemented in the underlying iTOUGH2 optimization toolset.



Ordering Information

GeoT  »  Register and Download – OR – If you have any questions or comments about licensing, please send an e-mail to

(Note: the iGeoT package also includes GeoT v2.1 Standard)

Software (Version) Description Commercial Non-Commercial, Academic U.S. Government, Collaborator
GeoT Standard (2.1) Multicomponent aqueous geochemical speciation and solute geothermometry with deep fluid reconstruction. Optionally allows for the re-equilibration of certain minerals while making reservoir temperature estimations. Up to 50 waters can be processed at the same time.
GeoT User’s Guide (pdf)
$750(a) $200 No Charge
GeoT Limited (2.1) Same functionality as the Standard version, but only two waters can be processed at the same time.
GeoT User’s Guide (pdf)
$150 No Charge No Charge
iGeoT (v1.0) Same functionality as GeoT V2.1 Standard; in addition iGeoT allows for seamless estimation of dilution factor, exsolved gas fraction/composition, and solute concentrations at depth (e.g., Al, Mg) by numerical optimization without the need of separate optimization software. iGeoT incorporates the iTOUGH2 parameter estimation engine into one, stand-alone application.
iGeoT User’s Guide (pdf)
(Note: the iGeoT package also includes GeoT v2.1 Standard)
$950(b) $350(c) No Charge
Each package includes executables for PC 32-bit/64-bit, Linux/Unix, and Mac OSX (command-line executables). Other platforms available upon request.
(a) $650 if upgrading from GeoT Limited
(b) $200 if upgrading from GeoT Standard, $850 if upgrading from GeoT Limited
(c) $150 if upgrading from GeoT Standard

License Information

License Type Distribution Comment License Agreement
Academic These are appropriate for individuals working in academic or not-for-profit research institutions who are using the software for strictly non-commercial purposes. Academic licenses are Department Licenses i.e., the code may only be used by individuals working in the department to which the software was licensed. Academic License Agreement: Executable Code
Commercial These are appropriate for commercial entities. Commercial licenses are Enterprise-wide Licenses. Commercial License Agreement: Executable Code
Government U.S. Government organizations are required to sign a no-cost government use license to obtain a copy of the software. Non-U.S. Government organizations are required to obtain an Academic license. Government License Agreement: Executable Code
Collaborator Certain modules may be distributed at no cost to Academic or Commercial Collaborators identified by the GeoT Developer Team. Collaborator License Agreement: Executable Code


The development of GeoT was supported by the U.S. Department of Energy, Geothermal Technologies Program, Energy Efficiency and Renewable Energy Office