Rock-Physics Model of Unconventional Carbonate-Clay Reservoirs with Complicated Pore Space Structure

A unified parametric rock-physics model is constructed, which makes it possible to estimate the effective elastic properties of mudstones and carbonate-clay rocks, taking into account the specific features of their void spaces. The model allows to take into account the anisotropy of elastic properties caused by the intrinsic anisotropy of clay minerals, oriented non-isometric voids and particles of clay minerals having a plate-like shape. The model assumes the separation of voids of carbonate and clay components. The model is based on the analysis of the microstructure of the Paleogene rocks of the Central and Eastern Pre-Ciscaucasia and the results of measurements of the velocity of elastic waves on the core of these rocks. For the analysis, we used the results of studying the rocks of the Oligocene: the Batalpashinskaya and Khadumsky suites, as well as the Eocene-Paleocene intervals — the Kumsky and Beloglynsky suites. The model is adapted to well log data in order to invert the parameters of the void space of rocks and establish petrophysical relationships between the velocity characteristics of the rocks and these parameters, as well as the content of organic matter, clay content and other characteristics of the rock composition.