| Abstract |
In an enhanced geothermal system (Egs) The heat energy is usually extracted from deep reservoir by circulating water (Cold water is injected and hot water is pumped). The fractures/Joints in geothermal reservoir play a significant role because they are the main flow conduits where permeability of the rock matrix is very low. Sometime a single fracture or fault extends very long can connect the injection and production wells [rawal and ghassemI, 2014; Pandey et al. 2014 and 2015]. The transmissivity of fracture is sensitive to fracture aperture and spatial heterogeneity in aperture field. During the egs operation the aperture is subjected to alteration due to dissolution/Precipitation of reservoir minerals during. The transmissivity alteration greatly influences the flow impedance and temperature drawdown at production well depending on the type of minerals, range of temperature and injection conditions. So the study of hydrologic evolution of egs is very important for planning of sustainable energy recovery [mroczek et al., 2000; Rabemanana et al., 2003 bachler and kohl, 2005]. We simulated the hydrologic evolution of egs for two types of rocks which very are common in earth's formation namely carbonate and silicate. For the numeral experiment we assumed that carbonate rock was only made of calcite (Caco3) And in silicate reservoir silica was present as amorphous silica (Sio2). We selected these minerals because these are more reactive than others and calcite is retrograde soluble while amorphous silica is prograde soluble (See fig. 1). Figure (1) Also shows that reaction rate increases with temperature for both calcite and amorphous silica. We also simulated for heterogeneous aperture field and compared the effect of heterogeneity on the evolution of reservoirs of two types of minerals. |