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Title: Transformation of seismic velocity data to extract porosity and saturation values for rocks

Transformation of seismic velocity data to extract porosity and saturation values for rocks For wave propagation at low frequencies in a porous medium, the Gassmann-Domenico relations are well-established for homogeneous partial saturation by a liquid. They provide the correct relations for seismic velocities in terms of constituent bulk and shear moduli, solid and fluid densities, porosity and saturation. It has not been possible, however, to invert these relations easily to determine porosity and saturation when the seismic velocities are known. Also, the state (or distribution) of saturation, i.e., whether or not liquid and gas are homogeneously mixed in the pore space, is another important variable for reservoir evaluation. A reliable ability to determine the state of saturation from velocity data continues to be problematic. It is shown how transforming compressional and shear wave velocity data to the ({rho}/{lambda},{mu}/{lambda})-plane (where {lambda} and {mu} are the Lame parameters and {rho} is the total density) results in a set of quasi-orthogonal coordinates for porosity and liquid saturation that greatly aids in the interpretation of seismic data for the physical parameters of most interest. A second transformation of the same data then permits isolation of the liquid saturation value, and also provides some direct information about the state of saturation. By thus replotting the data in the more » ({lambda}/{mu}, {rho}/{mu})-plane, inferences can be made concerning the degree of patchy (inhomogeneous) versus homogeneous saturation that is present in the region of the medium sampled by the data. Our examples include igneous and sedimentary rocks, as well as man-made porous materials. These results have potential applications in various areas of interest, including petroleum exploration and reservoir characterization, geothermal resource evaluation, environmental restoration monitoring, and geotechnical site characterization. (c) 2000 Acoustical Society of America. « less
Authors: ; ;
Publication Date:
OSTI Identifier:20216522
Resource Type:Journal Article
Data Type:
Resource Relation:Journal Name: Journal of the Acoustical Society of America; Journal Volume: 107; Journal Issue: 6; Other Information: PBD: Jun 2000
Country of Publication:United States
Language:English
Subject: 58 GEOSCIENCES; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; POROSITY; ROCKS; SEISMIC WAVES; WAVE PROPAGATION; VELOCITY; LIQUIDS; MONITORING; SEDIMENTARY ROCKS; IGNEOUS ROCKS; POROUS MATERIALS; EXPERIMENTAL DATA; THEORETICAL DATA