Seismic endoscopy: multi-offset multi-azimuth imaging around boreholes – data processing and experimental results |
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| Authors: | Florence Nicollin Frédéric Conil Dominique Gibert |
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| Institution: | Géosciences Rennes, UMR 6118 CNRS, Universitéde Rennes 1, 35042 Rennes Cedex, France |
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| Abstract: | An acoustic method, called seismic endoscopy, able to perform 3D imaging around shallow-depth boreholes is presented. A probe, composed of an isotropic source and a directional receiver working in the 20–100 kHz frequency range, provides images of cylindrical volumes having radii of a few metres, with an accuracy of centimetres and 25° azimuthal directivity. In order to obtain clear images of the medium discontinuities, multi-offset and multi-azimuth data acquisition allows specific algorithms to be used to determine vertical directivity correction, azimuthal focusing and reflected wave enhancement by cancellation of the tube waves. The method is tested with data acquired in an acoustic tank and with synthetic data. Initial experimental results at a test site demonstrate the performance of the seismic endoscopy probe. |
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