The role of thermophysical analysis in laboratory petrophysical core studies: An example from Saurashtra Basin rocks, India

Evaluating the physical properties of rocks and their spatial variations is essential for understanding reservoir characteristics and developing reliable hydrodynamic or basin models. This paper summarizes the findings of a comprehensive laboratory study on the thermophysical, elastic, and electric properties of 62 core samples from the Saurashtra Basin (India). The results of experiments, conducted under atmospheric conditions with various pore-filling fluids, enrich the petrophysical database within the area. The advanced thermophysical core analysis extends past its conventional uses of providing reliable input data for numerical heat transfer modeling and it can aid also in characterizing heterogeneous and anisotropic rocks. High-quality data on thermal conductivity and porosity enable the differentiation of sandstone into distinct groups, which is challenging with other standard approaches. Findings from microscopic analysis, NMR measurements, and rock physics modeling support this differentiation. Significant correlations were established among thermal conductivity, electrical conductivity, elastic wave velocities, density, and porosity within each group. This study demonstrates for the first time that the principal axes of thermal conductivity are connected with the polarization directions of slow and fast shear wave velocities in sandstones. Additionally, the paper discusses thermophysical monitoring as an efficient, non-contact method for identifying and controlling changes in core sample microstructure during laboratory studies, complemented by rock physics modeling. Thus, the demonstrated applications of thermophysical core analysis go beyond its common use and provide new insights to enhance understanding of a reservoir. • Thermal anisotropy is associated with S-wave velocity anisotropy in sandstones • Thermophysical analysis differentiates sandstones into five distinct groups • Close correlations among physical properties are established within each group • Microscopic analysis and NMR measurements support the differentiation • Thermophysical monitoring controls changes in rock microstructure during core analysis