No description available.

No description available.

No description available.

No description available.

No description available.

The hydro-mechanical effects of high pressure fluid injections into jointed rock are considered mostly in the context of Hot Dry Rock (HDR) geothermal energy systems. In Part I, the mai n aspects ari sing from the HDR research at the "Camborne School of Mines (CSM) and Los Alamos Nat iana 1 Laboratory (LANL) projects are reviewed. Previous approaches to fluid-rock interacti ons at these projects and important observed phenomena are highlighted. Fundamental aspects of rock joint geometry, mechanical behaviour and flow regimes within jointed rock are also reviewed. These aspects are then related to possible conditions in HDR systems. The role of in situ stress conditions is of great significance in this study and is reviewed theoretically and in detail for both the CSM and LANL project sites. The revi ew incl udes a comprehensi ve seri es of measurements, by different techniques, organised and interpreted by the author at the CSM project. In Part II, model development, the emphasis is on intermediate fluid pressures which are too high for simple diffusion alone and too low for tensile hydraulic fracturing. The dominant mechanical activity is one of joint shear. Strike-slip shearing due to fluid injection is examined in two dimensions with the numerical model FRIP, which has been extended by the author. Similar behaviour is examined in three dimensions with an analytical model which is linked to microseismic observations. This model explains the observed phenomenon of downward shear growth. Joint distribution and mechanical properties, and their effect on fluid diffusivity, are examined and used in analytical models of fluid pressure pulse propagation, tracer transport, and rock stress increment transfer. All models are used to help interpret field data, mainly from the CSM project. The models are also of potential application to hydrocarbon reservoir stimulation, liquid waste disposal and leakage from high pressure water tunnels.

The requirements for power generation systems have been reviewed together with the various energy sources available for them. Geothermal energy has been examined in more detail and the principal methods of recovering power from it which are currently employed are discussed. A novel method for improved power recovery from geothermal sources called the Trilateral Flash Cycle (TFC) system is described which has the special requirement of an efficient two-phase expander. Optimum results are obtained from this cycle if a working fluid is used which leaves the expander as dry saturated vapour. A binary mixture of hydrocarbons was therefore sought which by variation of the constituent proportions, would satisfy this requirement for a range of inlet temperatures when the condensing temperature is constant. Methods of estimating mixture properties are reviewed and the chosen thermodynamic model, as well as a computational procedure for evaluation of vapour-liquid equilibria of organic binary mixtures at high pressures, are described. This is based on the Redlich-Kwong- Soave cubic equation of state. By this means a mixture of n-pentane and 2,2-dimethylpropane (neopentane) was found to be the most suitable for the TFC system for expander inlet temperatures between 150-180'C. Temperature-entropy (T-S) diagrams of this organic binary mixture were obtained for several compositions. Bubble and dew pressures of (n-pentane + 2,2-dimethylpropane) have been determined experimentally for five different compositions at six different temperatures, (333.15 K, 353.15 K, 373.15 K, 393.15 K, 413.15 K, and 433.15 K). Vapour pressures of pure n-pentane and pure neo-pentane were also determined at these temperatures. The critical point of neo-pentane was measured to assess the accuracy of the isothermal compression apparatus used. Theoretical predictions were found to be in good agreement with experimental measurements.

Im Freistaat Sachsen werden ca. 11.000 Gebäude mit Erdwärme klimatisiert. Genutzt wird die Wärme aus der Tiefe vor allem bei Ein- und Mehrfamilienhäusern zur Heizung und Warmwasserbereitung. Bei Planung und Bau von Erdwärmeanlagen sind Aspekte der Qualitätssicherung und rechtliche Vorgaben zu beachten. Interessierten Bürgern, Planern und Bohrfirmen werden u. a. folgende Fragen beantwortet: Welche Nutzungsformen der Erdwärme gibt es? Welche Qualitätsanforderungen, Richtlinien und Gesetze sind einzuhalten? Wie wird eine Anlage richtig geplant? Wo und wie werden Bohrungen bei Behörden beantragt?

Η γεωθερμική ενέργεια είναι μία ήπια, εναλλακτική και ανανεώσιμη πηγή ενέργειας. Η παρούσα εργασία έχει ως αντικείμενο μελέτης τα δύο από τα πέντε γεωθερμικά πεδία του Νομού Ξάνθης, αυτά της Νέας Κεσσάνης και του Νέου Ερασμίου-Μαγγάνων. Στόχος της εργασίας είναι να χαρακτηριστούν τα γεωθερμικά πεδία αυτά και να προταθούν πιθανοί τρόποι αξιοποίησής τους. / Geothermal energy is a clean and renewable source of energy. This project has to do with two out of five geothermal fields of Xanthi, those of Nea Kessani and Neo Erasmio-Maggana. The purpose of this project is for those geothermal fields to be characterized and to propose possible ways to be exploited.

Im Freistaat Sachsen werden ca. 11.000 Gebäude mit Erdwärme klimatisiert. Genutzt wird die Wärme aus der Tiefe vor allem bei Ein- und Mehrfamilienhäusern zur Heizung und Warmwasserbereitung. Bei Planung und Bau von Erdwärmeanlagen sind Aspekte der Qualitätssicherung und rechtliche Vorgaben zu beachten. Interessierten Bürgern, Planern und Bohrfirmen werden u. a. folgende Fragen beantwortet: Welche Nutzungsformen der Erdwärme gibt es? Welche Qualitätsanforderungen, Richtlinien und Gesetze sind einzuhalten? Wie wird eine Anlage richtig geplant? Wo und wie werden Bohrungen bei Behörden beantragt?