Elsevier

Geothermics

Volume 37, Issue 6, December 2008, Pages 597-621
Geothermics

SolGeo: A new computer program for solute geothermometers and its application to Mexican geothermal fields

https://doi.org/10.1016/j.geothermics.2008.07.004Get rights and content

Abstract

The freely available computer program Solute Geothermometers (SolGeo) was written and tested using geochemical data and reported geothermometric temperatures from several geothermal wells from around the world. Subsurface temperatures for the Mexican geothermal fields of Cerro Prieto, Las Tres Vírgenes, Los Azufres, and Los Humeros were estimated based on different solute geothermometers and found to be generally in close agreement with measured well temperatures when considering errors in the calculations and measurements. For Los Humeros wells it was concluded that a better agreement of chemical geothermometric temperatures is observed with static formation than with bottom-hole temperatures (BHTs). It was also found that the widely used Na–K geothermometric equations generally give more consistent and more reliable temperature estimates than the other geothermometers, which should therefore be applied with caution.

Introduction

A plethora of geothermometric equations put forth for estimating subsurface temperatures from solute concentrations in geothermal waters are difficult to use without suitable computer software. In the 1970s, Truesdell (1976) reported computer program GEOTHERM, which was capable of calculating temperatures from seven geothermometric equations (see also Henley et al., 1984). Since then, numerous new equations have been proposed and used in geothermometric temperature calculations (see D’Amore and Arnórsson, 2000, or Verma, 2002, for relatively recent compilations of such equations).

Commercial program AquaChem (Version 5.1.33; http://www.swstechnology.com/software_product.php?tab=3&ID=1#index) contains 18 geothermometric equations (four for Na–K; one for K–Mg; one for Mg–Li; three for Na–Li; two for Na–K–Ca; four for quartz; three for sulfate-waters) and provides for modifying regression coefficients corresponding to most of the programmed equations, but does not allow changes to the sign (+ or −) of the coefficients. More recent equations such as those proposed by Nieva and Nieva (1987), Fournier (1991), Verma and Santoyo (1997), and Can (2002) are absent from AquaChem. El-Naqa and Zeid (1993) presented a computer program (GEOTHERM) for applying Na–K, Na–K–Ca, and silica (or quartz) geothermometers, but so far temperatures computed using this program have not been reported in the published literature.

Most geochemists use some kind of spreadsheets or hand calculators that probably lead to frequent errors, as discussed below. Therefore, there is a special need for developing freely available software that could facilitate these computations in an easy, friendly, efficient, and reliable way. With this need in mind, we developed computer program Solute Geothermometers (i.e., SolGeo) that includes 35 geothermometric equations for solute geothermometers (Table 1). A salient feature of the program is that the concentration of each chemical variable is converted to the measurement units required by each geothermometric equation (see Table 1 for these requirements) using updated values of atomic weights (e.g. Vocke, Jr., 1999; Verma et al., 2003, Wieser, 2006) and proper geothermal water density calculations and corrections (McCutcheon et al., 1993, Nicholson, 1993). Here, we present validation of SolGeo from a worldwide geothermal database and results from application to four Mexican geothermal fields.

Section snippets

SolGeo: a new computer program

Computer program SolGeo (for Solute Geothermometers) was written in Visual Basic 6.0; the main functions of the code are summarized in Fig. 1. It accepts input data as an Excel (*.xls) or a Statistica (*.sta; Version 5) file (example files are available from any of the authors on request). Thirty-five geothermometric equations and their respective applicability constraints used in SolGeo are listed in Table 1.

For each sample, the chemical variables Cl, HCO3, SO4, Na, K, Li, Ca, Mg, and SiO2

Geochemical databases for program validation and application

Geochemical data on well waters and measured bottom-hole temperatures (BHTs) were compiled from the following geothermal fields: (1) Berlin, El Salvador (D’Amore and Mejia, 1999); (2) Fushime, Japan (Okada et al., 2000); (3) Geysir, Iceland (Pasvanoglu, 1998); (4) Kizildere, Turkey (Gôkgôz, 1998); (5) Miravalles, Costa Rica (Fung, 1998); (6) Salihli, Turkey (Tarcan et al., 2000); (7) Seferihisar, Turkey (Tarcan and Gemici, 2003); (8) Takigami, Japan (Furuya et al., 2000); (9) Xiaotangshang,

Results and discussion

We processed both the worldwide and the Mexican databases with SolGeo. The information from the worldwide database was used for performance validation by comparing geothermometric temperatures given in the literature (tlit) against SolGeo computed temperatures (tSolGeo); the results are shown in Fig. 2 in the form of “Difference” values (see the figure caption for explanation). In Table 3 are listed the miscalculated samples showing greater than ±4 °C difference between tlit and tSolGeo.

Conclusions

In order to recognize and reduce errors when estimating subsurface temperatures in geothermal systems we developed computer program SolGeo. Here we discuss and illustrate its application to geothermal well waters from around the world, including Mexico.

It was concluded that static formation temperatures in geothermal wells should always be reported, which could be of significance when developing more reliable geothermometric equations. We suggest that K–Mg, Na–Li, Na–K–Ca, Na–K–Mg, and

Acknowledgements

We are grateful to Alfredo Quiroz Ruiz for the efficient computer maintenance. The second and third authors thank DGAPA-UNAM for providing financial support through the PAPIIT project IN-108408. We thank Mark Reed, an anonymous reviewer and the editors Sabodh K. Garg and Marcelo J. Lippmann for the numerous suggestions to improve the manuscript.

References (80)

  • R.O. Fournier et al.

    An empirical Na–K–Ca geothermometer for natural waters

    Geochim. Cosmochim. Acta

    (1973)
  • S. Furuya et al.

    Takigami geothermal system, northeastern Kyushu, Japan

    Geothermics

    (2000)
  • W.F. Giggenbach

    Geothermal solute equilibria. Derivation of Na–K–Mg–Ca geoindicators

    Geochim. Cosmochim. Acta

    (1988)
  • E. González-Partida et al.

    Evolution of the hydrothermal system at the geothermal field of Los Azufres, Mexico, based on fluid inclusion, isotopic and petrologic data

    J. Volcanol. Geotherm. Res.

    (2000)
  • E. González-Partida et al.

    Hydro-geochemical and isotopic fluid evolution of the Los Azufres geothermal field, Central Mexico

    Appl. Geochem.

    (2005)
  • R. Hurtado

    Developments in geothermal energy in Mexico. Part twenty-nine: scaling studies at the Cerro Prieto geothermal field

    Heat Recov. Syst.

    (1990)
  • L.S. Land et al.

    Geothermometry from brine analyses: lessons from the Gulf Coast, USA

    Appl. Geochem.

    (1992)
  • G. Manetti

    Attainment of temperature equilibrium in holes during drilling

    Geothermics

    (1973)
  • A. Mañon et al.

    Developments in geothermal energy in Mexico. Part thirteen: the operation of surface equipment for geothermal fluid conduction at Cerro Prieto I

    Heat Recov. Syst.

    (1987)
  • D. Nieva et al.

    Developments in geothermal energy in Mexico. Part twelve: a cationic geothermometer for prospecting of geothermal resources

    Heat Recov. Syst.

    (1987)
  • J.L. Palandri et al.

    Reconstruction of in situ composition of sedimentary formation waters

    Geochim. Cosmochim. Acta

    (2001)
  • Z.-H. Pang et al.

    Theoretical chemical thermometry on geothermal waters: problems and methods

    Geochim. Cosmochim. Acta

    (1998)
  • L.A. Pope et al.

    An experimental investigation of the quartz, Na–K, Na–K–Ca geothermometers and the effects of fluid composition

    J. Volcanol. Geotherm. Res.

    (1987)
  • R.M. Prol-Ledesma

    Pre- and post-exploitation variations in hydrothermal activity in Los Humeros geothermal field, Mexico

    J. Volcanol. Geotherm. Res.

    (1998)
  • J.A. Sampedro et al.

    Developments in geothermal energy in Mexico. Part thirty: conclusion of the corrosion in Mexican geothermal wells project

    Heat Recov. Syst.

    (1990)
  • E. Santoyo et al.

    Evaluation of capillary electrophoresis for determining the concentration of dissolved silica in geothermal brines

    J. Chromatogr. A

    (2005)
  • E. Santoyo et al.

    Determination of lanthanides in international geochemical reference materials by reversed-phase high performance liquid chromatography: an application of error propagation theory to estimate total analysis uncertainties

    J. Chromatogr. A

    (2006)
  • G. Tarcan et al.

    Water geochemistry of the Seferihisar geothermal area, Izmir, Turkey

    J. Volcanol. Geotherm. Res.

    (2003)
  • S.P. Verma et al.

    New improved equations for Na/K, Na/Li and SiO2 geothermometers by outlier detection and rejection

    J. Volcanol. Geotherm. Res.

    (1997)
  • S.P. Verma et al.

    Fluid chemistry and temperature prior to exploitation at the Las Tres Vírgenes geothermal field, Mexico

    Geothermics

    (2006)
  • S.P. Verma et al.

    Statistical evaluation of methods for the calculation of static formation temperatures in geothermal and oil wells using an extension of the error propagation theory

    J. Geochem. Explor.

    (2006)
  • S.P. Verma et al.

    Application of the error propagation theory in estimates of static formation temperatures in geothermal and petroleum boreholes

    Energy. Conv. Manage.

    (2006)
  • J. Andaverde et al.

    Uncertainty estimates of static formation temperatures in boreholes and evaluation of regression models

    Geophys. J. Int.

    (2005)
  • S. Arnórsson

    Geochemistry and geothermal resources in Iceland

  • A.G. Asuero et al.

    Fitting straight lines with replicated observations by linear regression. III. Weighting data

    Crit. Rev. Anal. Chem.

    (2007)
  • V. Barnett et al.

    Outliers in Statistical Data

    (1994)
  • P.R. Bevington et al.

    Data Reduction and Error Analysis for the Physical Sciences

    (2003)
  • F. D’Amore et al.

    Geothermometry

  • Díaz-González, L., Santoyo, E., Reyes-Reyes, J., in press, Tres nuevos geotermómetros mejorados de Na/K usando...
  • Cited by (67)

    • Equivalent imputation methodology for handling missing data in compositional geochemical databases of geothermal fluids

      2022, Geothermics
      Citation Excerpt :

      To plot the Schoeller diagrams, the Statistica software was also executed. Finally, to estimate the geothermometric temperatures, the SolGeo software (Verma et al., 2008) was applied. This section presents the modeling results obtained after applying the EI methodology developed.

    View all citing articles on Scopus
    View full text