Caratterizzazione dei parametri di un reservoir geotermico tramite la risoluzione del problema inverso e le simulazioni geostatistiche

Focaccia, Sara (2012) Caratterizzazione dei parametri di un reservoir geotermico tramite la risoluzione del problema inverso e le simulazioni geostatistiche, [Dissertation thesis], Alma Mater Studiorum Università di Bologna. Dottorato di ricerca in Geoingegneria, georisorse e ingegneria geotecnica, 24 Ciclo. DOI 10.6092/unibo/amsdottorato/4330.
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Abstract

BTES (borehole thermal energy storage)systems exchange thermal energy by conduction with the surrounding ground through borehole materials. The spatial variability of the geological properties and the space-time variability of hydrogeological conditions affect the real power rate of heat exchangers and, consequently, the amount of energy extracted from / injected into the ground. For this reason, it is not an easy task to identify the underground thermal properties to use when designing. At the current state of technology, Thermal Response Test (TRT) is the in situ test for the characterization of ground thermal properties with the higher degree of accuracy, but it doesn’t fully solve the problem of characterizing the thermal properties of a shallow geothermal reservoir, simply because it characterizes only the neighborhood of the heat exchanger at hand and only for the test duration. Different analytical and numerical models exist for the characterization of shallow geothermal reservoir, but they are still inadequate and not exhaustive: more sophisticated models must be taken into account and a geostatistical approach is needed to tackle natural variability and estimates uncertainty. The approach adopted for reservoir characterization is the “inverse problem”, typical of oil&gas field analysis. Similarly, we create different realizations of thermal properties by direct sequential simulation and we find the best one fitting real production data (fluid temperature along time). The software used to develop heat production simulation is FEFLOW 5.4 (Finite Element subsurface FLOW system). A geostatistical reservoir model has been set up based on literature thermal properties data and spatial variability hypotheses, and a real TRT has been tested. Then we analyzed and used as well two other codes (SA-Geotherm and FV-Geotherm) which are two implementation of the same numerical model of FEFLOW (Al-Khoury model).

Abstract
Tipologia del documento
Tesi di dottorato
Autore
Focaccia, Sara
Supervisore
Dottorato di ricerca
Scuola di dottorato
Ingegneria civile ed architettura
Ciclo
24
Coordinatore
Settore disciplinare
Settore concorsuale
Parole chiave
geotermia geostatistica simulazione modelli
URN:NBN
DOI
10.6092/unibo/amsdottorato/4330
Data di discussione
4 Maggio 2012
URI

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