Passive temperature tomography experiments to characterize transmissivity and connectivity of preferential flow paths in fractured media

摘要: The detection of preferential flow paths and the characterization their hydraulic properties are major challenges in fractured rock hydrology. In this study, we propose to use temperature as a passive tracer characterize fracture connectivity properties. particular, new tomography field method which borehole profiles measured under different pumping conditions by changing successively observation boreholes. To interpret these temperature- depth profiles, three step inversion-based framework. We consider first an inverse model that allows for automatic permeable from conditions. Then apply borehole-scale produce flowmeter inversion profiles. This second uses relationship between variations with velocities (Klepikova et al., 2011). third step, exploits cross-borehole tests, is aimed at inferring inter-borehole transmissivities. multi-step framework provides means including image connectivity. test proposed approach data obtained Ploemeur (N.W. France) aquifer, where full experiment was carried out 100 m boreholes 10 apart. identified several transmissive fractures correspond known corroborate well independent information, available tests geophysical data. Hence, although indirect, appears be promising characterizing patterns transmissivities main rock.