Thermal prospection of geothermal reservoirs by using thermoluminescence of quartz

The Kakkonda shallow reservoir, NE Japan; was evaluated in an initial hypothetical stage of the exploration condition in order to validate a new methodology based on 2 complementary models: (1) A new experimentally kinetic of quartz TL decay equation as a function of time and temperature, (2) A basic reservoir model governed by geothermal equations that consider the geothermal system as a control volume subdivided in vertical rectangular prisms that transport heat from the bottom to the surface where TL property of quartz is gradually decayed due to this ancestral heating flow. This model uses the following equation coupling: the Fourier equation as the heat flux bottom source simulator, the vertical unsteady state heat conduction equation as the geothermal gradient profiles simulator, the volumetric balance of heat reservoir equation as the global parametric calibrator of the system conditions, and the surface answer of geoprocessing samples simulated by the kinetic equation as the heat sensor. The strategy of system solution involved the following steps: the equations development by experimental data validation, parameterization, iterative numerical evaluation process by using the same size of the grid, vectors, and matrixes; and finally, validation, until reservoir parameters convergence. This new methodology was tested in the shallow reservoir of the Kakkonda geothermal field, from 0 m. to 1500 m. The main products of this new methodology evaluation are profiles of temperatures vs. depth simulation, as a new geothermometer of quartz TL; and new geothermal potential map estimation in Megawatts. Thermoluminescence of quartz is an effective technique to evaluate geothermal activity. The Kakkonda shallow reservoir has been effectively modeled with this methodology. This simulation gives to geoscientist the opportunity to upgrade classic conceptual model in a simple, quick, low cost and useful numerical model for geothermal prospecting, optimizing detection of geothermal systems in an early stage of exploration condition.