119 5. Contribution of seismic and acoustic methods to the characterization of karstic formations in the vicinity of the well. The hydraulic slug tests show in some cases a very rapid propagation of the pressure wave over large distances (up to more than 100 m). These observations have enabled the mapping of a diffusivity distribution and illustrated the important connections between the wells (Figure 5.1, bottom). Preferential connections are visible along the N90 direction (wells M13-M21M22-M19 and wells M04-M06-M11). Ultimately it was considered crucial to better define the geometry of the reservoir with a resolution compatible with both the scale of a well, and also with the scale of the entire experimental site. It was decided that high-resolution geophysical tools are well designed to undertake this kind of investigation. Figure 5.1 Hydrogeological Experimental Site in Poitiers. Top: site map and well locations. Bottom: diffusivity map from slug test.
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