| In the first part of this thesis, a steady-state temperature field coupling convection and conduction is solved for a circular borehole. The solution is compared to two kinds of temperature field, caused by either convective or conductive heat transport.; Then, the transient temperature field is solved separately for the fluid and the rock, and has been achieved from energy conservation by coupling convective heat flow carried by an injected fluid from a borehole, and local heat conduction between a fluid boundary layer and a solid grain. Finally, the thermo-poro-elastic stress field around the borehole is calculated by using thermal and pore pressure "expansion potential".; Thermoelastic stresses induced by temperature changes in a solid are higher in a region filled by a hot fluid. This implies radical increase of {dollar}sigmasbtheta{dollar} at a borehole wall during hot fluid injection, which may trigger shear failure. Conversely, during cold fluid injection, radical {dollar}sigmasbtheta{dollar} reduction at a wall may cause hydraulic fracture initiation. (Abstract shortened by UMI.)... |
