Seismic imaging of a carbonate rock block with fracture-induced anisotropy

TitleSeismic imaging of a carbonate rock block with fracture-induced anisotropy
Publication TypeConference Proceedings
Year of Conference2020
AuthorsNakata, R, Matonti, C, Nakata, N, Guglielmi, Y, Viseur, S
Conference NameSEG Annual Meeting 2020
Abstract

Seismic experiments on a meter-scale rock sample characterize spatial heterogeneities at outcrop scale, and potentially bridge the gap between laboratory experiments and conventional field seismic experiments. Using a real seismic dataset of a fractured carbonate rock sample, we demonstrate strong potentials of small rock-block experiments, and endeavor towards full waveform analyses, such as full waveform inversion. We were able to place sources and receivers to surround the sample and acquired the data to optimally illuminate internal structures along chosen 2D planes. The observed waveforms comprised clear but complicated P- and S-wave direct arrivals and free surface reflections from all sides of the block. Beamforming (slant-stacking) was capable of extracting hidden complex arrivals. By exploiting both P and S arrivals, we successfully estimated parameters of apparent tilted transverse anisotropy with a symmetry axis normal to the 10 cm-scale fractures. In order to delineate heterogeneities in the sample due to fractures, we proposed to apply full waveform inversion to the dataset. With synthetic studies, we illustrated that the velocity model can be nearly perfectly reconstructed at a half-wavelength scale.

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