Characterizing flow in the first hundred-meter depth of a fractured aquifer using hybrid seismic methods, acoustic logging, and flow-log measurements

Understanding subsurface flow, especially in fractured rocks only housing water through a few preferential pathways, is still challenging. The point mainly associated with the poor accessibility of and lack accurate representations for both heterogeneity spatial distribution bearing bodies. This notwithstanding, highly-resolved geophysical investigations bring new images subsurface. exemplified over limestone aquifer at site scale (for example, that radius influence an extraction well). On experimental site, situated Cher region (France), two boreholes have been drilled field experiments. Full Waveform Acoustic Logging (FWAL) seismic experiments were conducted. Hybrid imaging, which consists combining refraction reflection results, has carried out. Based on four-step procedure, processing refracted reflected waves provided sections. After assemblage, these sections produced first step extended time reflectivity section starting from surface and, second step, depth after calibration Vertical Seismic Profile (VSP) acoustic data. However, even Very High Resolution (VHR) methods do not sufficient vertical resolution to describe accurately geological formation. processed separate different wave fields, extract criss-cross events build index log. A log fracturation index, based P-wave velocity measurements, was computed detect presence fractures. calibration, under assumption slower velocity, higher permeability – porosity, 3D block can inform areas where flow should occur. At open wellbore, loggings measure velocities short distance within well also features crosscut by well. Finally, measurements confirm occurrence flowing horizons previously marked data are therefore suited image contrasted hydraulic properties systems usually poorly documented.