Integrated Characterization Applied to a Geothermal System Influenced by Geological Structures

Abstract

Even though geothermal systems can be present both in sedimentary and volcanic rocks, the majority are located inside volcanic type. Volcanic geothermal systems are characterized with high temperature containing high-quality energy, but their distribution is subject to geographical limits. Another characteristic is that magmatic set systems can be found in regions with basaltic volcanism. However, in geothermal volcanic systems it is important to note that geothermal resource is part of a geologic system where geologic factors such as lithology, faults, fractures, rock mechanics, fluid chemistry and geochemistry are influence factors. The discontinuity in the rock formation due to structures is the reason for variety of different characteristics which, influences in a heterogeneous behavior changing from well to well, physical, thermodynamic and mechanical conditions. An example of this behavior can be found in a particular zone of the Los Humeros Mexico geothermal field which is characteristic of a volcanic system highly dominated by its structures distribution. In this study are used both, static and dynamic characterization methodologies with objective for determining the wells performance which, helps to acquire criteria for planning field management. Data used are correlation of the formation lithology, geothermal interest levels, length thicknesses, circulation losses during drilling. Also the measurements temperature-pressure for determining thermodynamic profiles of each well are used. It is a common characteristic that producer wells of this field are of high enthalpy and correspondingly with steam fractions upper 0.75. The mass flow production of field overall wells is no more than 40 t/h, however the study zone involves two of the wells whose mass flow production is over 60 t/h. The behavior found of these different characteristics of this field, leads to assume that this is a compartimented system.