Available approaches for increasing the producibility of geothermal wells in natural fracture systems by optimizing their placement, design, and stimulation

Maybe the greatest value of technology in geothermal energy issues can be assessed in<br>terms of its ability to reduce risk. The present contribution only addresses subsurface matters<br>and, even more specifically, how naturally fractured geothermal reservoirs could be more<br>efficiently tapped and developed in the framework of EGS operations. Lastly, among the two<br>aspects which have to be investigated in EGS projects, i.e. temperatures and flow rates, only<br>the latter is considered here, assuming that the isotherm geometry can, for instance, be<br>constrained by MT (magneto-telluric) surveys looking for electrically conductive altered rocks<br>(clay alteration zones) or other techniques.<br>The ability to characterize NFSs (natural fracture systems) in the early field development<br>stage of an EGS project reduces economic risk because it enables the development team to<br>determine optimal well placement and trajectories. Characterizing, tapping and developing a<br>geothermal NFS, as well as predicting the heat and fluid flows in response to hot water<br>extraction and cooled water re-injection, is a challenging task that span multiple disciplines<br>and multiple scales.