none 10.1190/1.1438855 Society of Exploration Geophysicists Society of Exploration Geophysicists 186 4722855 5981 2025121010404230900 10.1190 2025-12-10T15:40:49Z 2002-10-11T15:40:18Z 297 Geophysics 1942-2156 0016-8033 04 01 1961 04 01 1961 26 2 J. Geertsma †Koninklijke/Shell Exploratie en Produktie Laboratorium, The Netherlands. D. C. Smit †Koninklijke/Shell Exploratie en Produktie Laboratorium, The Netherlands. Abstract Biot's equations for the propagation of dilatational waves in fluid-saturated porous solids in the low-frequency range are analyzed for the purpose of application in geophysical research. The deformation constants of the system are unraveled in terms of compressibilities and porosity, and suitable approximate solutions for wave velocity and attenuation of the waves of both the first and the second kind are obtained. A saturated elastic porous solid is found to behave, as far as the wave of the first kind is concerned, approximately as a standard element. The wave of the second kind rapidly dies out with increasing distance from the source and consequently one might infer that in seismic studies only the wave of the first kind needs consideration. It is shown, however, that its presence has an effect upon the reflection and absorption at any interface between two different fluid-saturated porous solids. At such an interface a wave of the second kind is again generated. General formulae for the reflection and absorption for normal incidence at the interface are obtained, which include the effect of second-wave generation. Additional results of the investigation are the following: A rather simple formula for the speed of sound in sedimentary rocks (the wave of the first kind) is obtained, which has to replace the so-called “time-average relation” now sometimes used. A comparison between the results obtained here and published results on wave propagation in simpler fluid-solid systems, such as, for instance, suspensions, showed some weak points in the older theories. Suggestions for possible improvements are given. 04 01 1961 04 01 1961 04 01 1961 169 181 10.1190/1.1438855 https://pubs.geoscienceworld.org/geophysics/article/26/2/169/67566/SOME-ASPECTS-OF-ELASTIC-WAVE-PROPAGATION-IN-FLUID https://pubs.geoscienceworld.org/seg/geophysics/article-pdf/26/2/169/3152510/169.pdf https://pubs.geoscienceworld.org/seg/geophysics/article-pdf/26/2/169/3152510/169.pdf http://geophysics.geoscienceworld.org/cgi/doi/10.1190/1.1438855