Dynamic permeability of heterogeneous porous rocks having strong permeability fluctuations and its effects on seismic attenuation and velocity dispersion

RUBINO J. GERMÁN; MONACHESI LEONARDO; GUARRACINO LUIS; MÜLLER TOBIAS; HOLLIGER KLAUS

Las Vegas

Congreso; SEG International Exposition and Eighty-Second Annual Meeting; 2012

SEG society of exploration geophysicists

Wave-induced flow due to the presence of mesoscopic heterogeneities represents an important seismic attenuation mechanism in fluid-saturated porous rocks. In this context, it is known that in the presence of strong permeability fluctuations, there is a discrepancy between the effective flow permeability and the effective seismic permeability, that is, the permeability controlling seismic attenuation due to wave-induced fluid flow. While this subject has been analyzed for the case of random 1D media, the corresponding 2D and 3D cases remain unexplored. In this work, we seek to address this problem through the numerical analysis of heterogeneous 2D rock samples having strong permeability fluctuations. In order to do so, we employ a numerical oscillatory compressibility test to determine attenuation and velocity dispersion due to wave-induced fluid flow in these kinds of media and compare the responses with those obtained by replacing the heterogeneous permeability fields by homogeneous ones, with permeability values given by the arithmetic and harmonic average permeabilities as well as the effective flow permeability of the sample. The latter is estimated in a separate upscaling procedure by solving the steady-state flow equation for the rock sample under study.