Methods for exploration of thermal waters and a geological-commercial assessment of their deposits

Abstract

The concepts of the regularities of thermal water occurrence, the conditions of their occurrence and circulation and hydrogeothermal indices of thermal water deposits are the basis of the methods of thermal water exploration. According to the conditions of occurrence and circulation all thermal waters are divided into two types: stratal and fissure-veined waters. Stratal thermal waters occur in platform regions, foredeeps and intermontane areas, and extend to most large areas (tens and hundreds of thousands of square kilometers). The fissure-veined thermal waters occur in folded areas and have a local nature of outlet and extend to small areas (from portions to units of square kilometers). The methods of exploration and determination of the exploitation resources of thermal water deposits of stratal and fissure veined type are different. Based on the analysis of the available geological, hydrogeological and geothermal data on the basins in which stratal thermal water deposits are found, the principal aquifers and complexes with thermal water of usable quality for heat supply are determined and distinguished. Exploration of these aquifers, and complexes distinguished, is conducted for determination of calculating parameters required for calculation of exploitation resources. These resources are determined by means of hydrodynamic computation, taking into account the boundary conditions (infinite bed, semi-finite bed, bed-strip, etc.). Exploration of the fissure-veined thermal water deposits is carried out in previously established thermal anomalies using the ground geophysical methods and the complex hydrogeothermal survey at a large scale, by means of which the structure and sizes of a deposit, composition and temperature of thermal waters (superheated waters) and the approximate possible heat quantity of a deposit are determined. The preliminary data obtained are made more precise by drilling of exploration wells, and the deposit resources are estimated by the method of pumping tests of thermal waters from a group of wells. The hydraulic method is the principal one for determining exploitation resources of the fissure-veined thermal waters. In conducting exploration works at the thermal water deposits (and superheated waters) the main technical-economical indices are defined. The question of industrial estimation of the thermal water deposits arises before the hydrogeologists at all stages of their exploration, from the stage of prospecting works to their exploitation for industrial purposes. The economic significance of thermal water deposits, and economic efficiency in their exploitation are established on the basis of geological-economic estimation. The above methods enable the researcher to plan the succession of development of thermal water deposits.