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Fracture Characterization from Elastic Waves - An Ultrasonic Experimental Approach
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 74th EAGE Conference and Exhibition incorporating EUROPEC 2012, Jun 2012, cp-293-00007
- ISBN: 978-90-73834-27-9
Abstract
The main goal of this work was to estimate the preferential fracture orientation of a cracked medium based on cross-correlated S-wave seismograms analysis and Thomsen parameters. For this purpose, we analysed ultrasonic measurements of elastic (P and S) waves in a physical-modelling experiment with an artificially anisotropic cracked model. The solid matrix consisted of epoxy-resin, and small rubber-strip pieces simulate weakly-filled cracks. The anisotropic cracked model has three regions with three different fracture orientations. We used rotation of S1 and S2 polarizations for a cross-correlation analysis of the orientations, and P and S-wave measurements to evaluate the anisotropic parameters gamma and epsilon. The shear-wave source has a dominant frequency of 90 kHz, which corresponds to low wavelengths as compared to to the crack aperture, ensuring effective-media behaviour. Integrating the results from cross-correlation with anisotropic parameters analysis, we were able to estimate fracture orientation in anisotropic cracked model. The anisotropy parameter gamma showed good agreement with the cross-correlation analysis and, beyond that, provided additional information about the crack orientation that cross-correlation alone did not resolve.