HR: 0800h
AN: MR31C-0519    [Abstracts]
TI: Equivalent Elastic Models
AU: * Ruiz, F J
EM: fjruiz@stanford.edu
AF: Stanford University, 397 Panama Mall, Mitchell BLDG., Stanford, CA 94305, United States
AU: Dvorkin, J
EM: jack@stanford.edu
AF: Stanford University, 397 Panama Mall, Mitchell BLDG., Stanford, CA 94305, United States
AB: We theoretically find the aspect ratios of the inclusions required to match the elastic-wave velocity of rock as predicted by the Differential Effective Medium theory (DEM) with those predicted by classical empirical rock physics equations of Wyllie et al. (1956) and Raymer et al. (1980). The aspect ratio range thus established is remarkably narrow (between 0.1 and 0.2) and stable in the porosity range between zero and 0.4. This conclusion is valid for pure mineralogies (calcite and quartz) as well as for mixed sand/shale mineralogies. It is not only applicable to the P-wave velocity but also matches the S-wave velocity as predicted by such empirical equations as of Castagna et al. (1993) and Krief et al. (1990). The goal of this exercise is to find the range of inputs into a fundamental micromechanical model (DEM) that is relevant to real rock data. Once the stability of such input is established, it can be perturbed to predict the elastic-wave velocity versus porosity and pore geometry beyond past experimental evidence which may be especially essential for carbonate rock where the shapes and structures of the pores may sufficiently vary in accordance with depositional and diagenetic history. For example, using aspect ratio 0.1 with DEM allows us to accurately match two carbonate laboratory datasets in a wide porosity range.
DE: 5100 PHYSICAL PROPERTIES OF ROCKS
DE: 5102 Acoustic properties
SC: Mineral and Rock Physics [MR]
MN: 2007 Fall Meeting