Developments in geothermal energy in Mexico—part twenty-eight: The role of petrophysical studies in the development of the Mexican geothermal resources

Abstract

The host rocks of geothermal reservoirs perform important functions as structural elements and storage media for the hot reservoir fluids. They also provide the transport medium of the fluids. Characterizing the ability of geological formations to perform these functions is a fundamental requirement for both feasibility studies and the development and exploitation of geothermal resources. The heat content of the system, the fraction of recoverable heat, and the rate at which this fraction can be extracted are important factors in the technical and economic viability of a geothermal project. They depend greatly on the characteristics of the bearing rocks. Only a limited amount of appropriate rock property data is available. This restricts geothermal energy development. Laboratory measurements under simulated geothermal reservoir conditions in rock samples from drill cores have proved to be the most powerful tool to generate the necessary rock property information. Typical results of a number of petrophysical properties which have been determined using this technique on rocks from four Mexican geothermal fields are presented and discussed. These results illustrate the potential and importance of petrophysical research programmes as a tool to generate data and understand the properties and behaviour of reservoir rocks.