Developments In Geothermal Energy In Mexico-Part Twelve, A Cationic Geothermometer For Prospecting Of Geothermal Resources

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Journal Article: Developments In Geothermal Energy In Mexico-Part Twelve, A Cationic Geothermometer For Prospecting Of Geothermal Resources

Abstract
In order to assess the economic value of a geothermal field, it is important to know the temperature distribution and in particular the temperature in the main part of the reservoir. A description of the development of a chemical geothermometer based on the concentrations of the four main cationic constituents of a ground water, namely Na+, K+, Ca2+, and Mg2+. Chemical composition and underground temperature data for a number of well water samples were assembled. The list includes samples from low-, medium- and high-temperature reservoirs. Assumptions were adopted which permitted the formulation of a simple linear relationship between the reciprocal of the absolute temperature, and the concentration of cation species in the ground water, for any hypothetical rock-solution cation exchange reaction. A systematic, computerised procedure was devised, which analysed a large number of possibilities for the rock-solution cation exchange reaction, and for partitioning of the data into two, three and four subgroups based on the composition parameters √Ca2+/Na+ and √Mg2+/Na+. The problem of the mixing of geothermal and cold shallow waters was considered from a prospecting standpoint. A dilution-intensitive geothermometric expression, to be applied to samples showing 'preliminary signs' of a geothermal origin, was developed and integrated within the geothermometer. The resulting geothermometer is able to predict the reservoir temperature, based on the composition of relatively dilute hot-spring waters. Moreover, the new geothermometer shows a fit to the well water data, superior to that of published geothermometers based on cation composition of natural waters, over the entire temperature range.

Authors 
D. Nieva and R. Nieva








Published Journal 
Heat Recovery Systems and CHP, 1987





DOI 
10.1016/0890-4332(87)90138-4


 

Citation

D. Nieva,R. Nieva. 1987. Developments In Geothermal Energy In Mexico-Part Twelve, A Cationic Geothermometer For Prospecting Of Geothermal Resources. Heat Recovery Systems and CHP. (!) .