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.

Multistage hydraulic fracturing of horizontal wells continues to be a major technological tool in the oil and gas industry. Creation of multiple transverse fractures in shale gas has enabled production from very low permeability. The strategy entails the development of a Stimulated Reservoir Volume (SRV), defined as the volume of reservoir, which is effectively stimulated to increase the well performance. An ideal model for a shale gas SRV is a rectangle of length equal to horizontal well length and width equal to twice the half length of the created hydraulic fractures. This project focused on using the Multistage Transverse Fractured Horizontal Wells (MTFHW) for two novel applications. The first application considers using the SRV of a shale gas well, after the gas production rate drops below the economic limit, for low grade geothermal heat extraction. Cold water is pumped into the fracture network through one horizontal well drilled at the fracture tips. Heat is transferred to the water through the fracture surface. The hot water is then recovered through a second horizontal well drilled at the other end of the fracture network. The basis of this concept is to use the already created stimulated reservoir volume for heat transfer purposes. This technique was applied to the SRV of Haynesville Shale and the results were discussed in light of the economics of the project. For the second application, we considered the use of a similarly created SRV for producing hydrocarbon products from oil shale. Thermal decomposition of kerogen to oil and gas requires heating the oil shale to 700 degrees F. High quality saturated steam generated using a small scale nuclear plant was used for heating the formation to the necessary temperature. Analytical and numerical models are developed for modeling heat transfer in a single fracture unit of MTFHW. These models suggest that successful reuse of Haynesville Shale gas production wells for low grade geothermal heat extraction and the project appears feasible both technically and economically. The economics of the project is greatly aided by eliminating well drilling and completion costs. The models also demonstrate the success of using MTFHW array for heating oil shale using SMR technology.

The aim of this master's thesis is to create a project of a small power plant in the Czech republic, which would be powered by geothermal energy as a renewable energy source. Followed by evaluation of economic effectiveness and return of that investment. For which I use known methods for evaluation and investment decision making.