Numerical solution of type problems in two and three dimensional anisotropic geothermal domains with sources and sinks of fluid flow.application to flegrea area reservoir

Resumen

Resumen de la tesis: This Dissertation presents the most advanced numerical analysis methods used for the sustainable use of geothermal energy in high enthalpy domains. The research work introduces and develops the techniques for a correct assessment of geothermal potential through the development and implementation of an advanced software. The thesis includes 5 chapters. In the first chapter, the methods of exploitation of geothermal energy for the different types of domains are introduced based on geothermal potential and enthalpy. For the high enthalpy domains, the characteristic physical parameters used to estimate the the exploitation potential of the geothermal domain and the productivity of the plants are described, such as the characteristics of the soil, the flow of fluid and the thermal source. At the end, the main types of plant and the methods of exploitation of the domain are introduced, these are the heat extraction wells and the extraction or re-injection of the fluid wells. The second chapter presents the theoretical foundations of the physical problem studied. The physical governing equations of the problem are based on the laws of conservation of mass, energy and momentum applied to porous media. Depending on the characteristics of the porous medium, composed of a solid matrix and the fluid, the system can be studied as incompressible or compressible and saturated or not. Well-known approaches such as Oberberk-Buossinesq are applied in the work. The solution of the physical model, composed of a system of partial differential equations, is solved and discretized using the discontinuous Galerkin method (DGM). Chapter 3 introduces the various resolution techniques for this type of highly non-linear systems based on differential operators. Finally, the various types of elements implemented through the weight functions (shape functions) are presented for the 2D and 3D systems. In the chapter 4 the structure and the implementation methods of the developed software, ”Geothermal Software”, are presented, which allows the numerical study of two-dimensional geothermal domains. In the chapter 5, using the developed software, complex theoretical and real problems are studied. Among the theoretical problems studied there are the Bénard, Elder and Yusa problems. For these the temperature field, stream function and components of the velocity vector results are presented. http://repositorio.bib.upct.es/dspace/