Acoustic behaviour of sedimentary rocks: geological properties versus Poisson's ratios

Velocity transforms are essential for the extraction of geologic information from seismic reflection data sets and/or predicting porosity from wireline logging data. Most commonly used transforms, like the Wyllie time average equation, the Raymer modified time-average equation, and the Gardner equation are all based on empirical relationships extracted from relatively small, "clean" mono- and bimineral and mostly siliciclastic data sets and generally fail to explain the acoustic relationships within multimineral data sets. To extract globally significant relationships between geologic and acoustic parameters, more than 2800 plug measurements were collected. More than two-thirds of the data were our own measurements; the others were from the literature. This data set covers nearly all sedimentary environments and mixtures of those as well as the entire range in petrophysical properties. © 2007 Society of Exploration Geophysicists.