Relations of rock structure and composition to petrophysical and geomechanical rock properties:: Examples from Permocarboniferous red-beds

This study relates textural properties to physical and mechanical properties of coarse grained sedimentary rocks of Permocarboniferous age. As an equivalent to rock texture the principle of "geomechanical order" is applied. The geomechanical order describes a rock as a function of its structural and compositional order which are derived from petrological analyses. Our results indicate that rock properties like density and porosity are stronger dependent on the structural order, while strength properties additionally depend on the compositional order. The ultrasonic wave velocity responds to both structural and compositional properties. These evidences imply that the geomechanical order is not an independent parameter but a variable function of structural or compositional features, which needs specification for correlation purposes to distinct physical and mechanical rock properties.