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High enthalpy - Low enthalpy geothermal reservoir

Keywords: geothermal numerical model, simulation, GIS, thermal response test, borehole heat exchangers
Fig. 1. Three-dimensional numerical model as plotted by TOUGH2Viewer. Different colors indicate different geological layers (picture by S. Bonduà).
Fig. 2. Discretization of the simulation domain through Voronoi 3D as plotted by TOUGH2Viewer (picture by S. Bonduà).
Fig. 3. Hydraulic circuit of a borehole heat exchanger field and extract from the numerical simulation (picture by F. Tinti).

The best practice to exploit high enthalpy geothermal reservoirs also entails the design, development and use of numerical codes for simulation works. Usually, the geothermal reservoir is fractured and a non-isothermal flow of multicomponent, multiphase fluids with in case mass exchange is present. At present, we use iTOUGH2 (a flexible and robust numerical geothermal simulator extensively used all over the world) for research and commercial activities. Nowadays, there are much commercial and non-commercial software that manage and display the input-output data of iTOUGH2, but in general, there are severe limitations on the use of unstructured grids. The research group has therefore developed an integrated software system to facilitate the mesh creation and population of irregular grids based on the customization of the open source GRASS GIS and an in-house 3D viewer written in JAVA called TOUGH2Viewer.

The research group collaborates with the Lawrence Berkeley National Laboratory (California, USA) and with SAIPEM SpA for the use of a software code dedicate to the coupled modelling of well flow and reservoir, for the study of geothermal resources (T2WELL-EWASG).

The exploitation of shallow underground, as geothermal reservoir where storing and retrieving thermal energy, concerns the low-enthalpy geothermal energy. The main contributions of the research team concern the modelling of petro-physical properties of the reservoir and its interaction with the many alternatives of geoexchanger systems, by the use of geostatistics and numerical modelling. A top application concerns Thermal Response Test (TRT), for the on-site characterization of the underground properties to improve the simulation of geo-exchanger behaviour in working phases. The team adheres to the Committee for Energy Conservation through Energy Storage of the International Energy Agency (IEA-ECES) and it collaborated in the drafting of the final document of Annex 21, Subcommittee for TRT.

Main publications

Berry, P., Bonduà, S., Bortolotti, V., Cormio, C., Vasini, E.M. A GIS-based open source pre-processor for georesources numerical modeling, Environmental Modelling and Software, 62, 2014, pp. 52-64.

Bonduá, S., Berry, P., Bortolotti, V., Cormio, C. TOUGH2Viewer: A post-processing tool for interactive 3D visualization of locally refined unstructured grids for TOUGH2, Computers and Geosciences, 46, 2012, pp. 107-118.

Cormio, C., Berry, P., Bonduà, S., Bortolotti, V., Innovative tools for continuum discretization, better management of TOUGH2 input data and analysis of the numerical simulation results. Proceedings of TOUGH Symposium 2012, Lawrence Berkeley National Laboratory, Berkeley, California, September 17-19, 2012.

Focaccia, S., Tinti, F., Monti, F., Amidei, S., Bruno, R., Shallow geothermal energy for industrial applications: a case study, Sustainable Energy Technologies and Assessments, 16, 2016, pp. 93-105.

Bruno, R., Tinti, F., Focaccia, S., Estimating Thermal Response Test Coefficients: Choosing Coordinate Space of the Random Function, Mathematical Geosciences, 48(1), 2016, pp. 3-23.

Tinti, F., Pangallo, A., Berneschi, M, (..), Meggiolaro M., How to boost shallow geothermal en-ergy exploitation in the Adriatic area: the LEG-END Project approach, Energy Policy, 92, 2016, pp. 190-204.

Tinti, F., Bruno, R., Focaccia, S., Thermal re-sponse test for shallow geothermal applications: a probabilistic analysis approach, Geothermal Ener-gy, 3(1), 2015, 20 pp.

Tinti, F., Barbaresi, A., Benni, S., Torreggiani, D., Bruno, R., Tassinari, P., Experimental analysis of thermal interaction between wine cellar and un-derground, Energy and Buildings, 104, 2015, pp. 275-286.

Rajver, D., Prestor, J., Tinti, F., Comparison of Geological and Shallow Geothermal Characteris-tics of some Adriatic Regions in the Circum–Adriatic Countries (LEGEND project), in: Proc. World Geothermal Congress 2015, 2015, pp. 1 – 15.

Tinti, F., Barbaresi, A., Benni, S., Torreggiani, D., Bruno, R., Tassinari, P., Experimental Analysis of shallow underground temperature for the assessment of energy efficiency potential of under-ground wine cellars, Energy and Buildings, 80, 2014, pp. 451-460.

Bruno, R., Mercuri, S., Tinti, F., Witte, H., Probabilistic approach to TRT analysis: evaluation of groundwater flow effects and machine - borehole interaction, Proceeding of European Geothermal Congress 2013, Pisa, Italy, 3-7 June 2013 – 5 pp.

Focaccia, S., Tinti, F., An innovative Borehole Heat Exchanger configuration with improved heat transfer, Geothermics, 48, 2013, pp. 163-170.

Bruno, R., Focaccia, S., Tinti, F., A software tool for Geostatistical Analysis of Thermal Response Test data: GA-TRT, Computers & Geosciences, 59, 2013, pp. 163-170.

Research projects

Low-Enthalpy Geothermal Reservoir
H2020 European Project GEOTeCH – Geothermal Technology for Economic Cooling and Heating. Grant Agreement n.: 656889.
Characterization of underground thermal properties for geothermal applications in rural context – Collaboration with Agronomics School, UNIBO.

High-Enthalpy Geothermal Reservoir
Agreement DICAM – SAIPEM n°5000018160 for Studies and Research on Reservoir Engineering (2013 – 2014)

MAC – GEO Project financed By Tuscany Region “Modellazione matematica di sistemi geotermici per la definizione di strumenti di decisione da utilizzarsi nelle procedure di controllo di concessioni geotermiche”, in collaboration with University of Florence, CINIgeo and CNR.

Characterization of high enthalpy geothermal reservoir of Torre Alfina – Research Agreement with Umbria Region.