Interplay of Porosity, Mineralogy, TOC and Maturity on the Acoustic Properties of Organic Rich Damodar Valley Shales.

Organic rich shales (ORS) resources have occupied an important place in the world's hydrocarbon production to meet energy demands. Given the complexity of storage, flow and the associated strength and elastic properties, characterizing these resources using multiphysics approach has become an essentiality. Multiphysics measurements of the acoustic and conductivity properties in shales provide understanding of the constraints influencing the distribution of the above-mentioned formation. Multiphysics approach help quantify the textural heterogeneity character and resulting flow capacity of the organic-rich formation. In this work, we carried out a comprehensive characterization of the organic-rich shale samples from the Damodar Valley Basin in northeastern-central India, which has rich coal deposits of the Gondwana age. The area has remained under-reported because of various strategic interests but, more surprisingly, also under-characterized. These shales have been of particular interest as these have been the place of the first shale gas pilot project in India. We carried out quantitative mineralogical analysis of the associated variability in porosity estimates and the resulting compressional and shear waves. We used an ultrasonic wave (1Mhz) propagation setup to measure compressive and shear wave velocities at benchtop conditions. The resulting velocities were plotted against the pore size distribution from mercury injection capillary pressure (MICP), maturity and TOC content. Among other inferences that we have deliberated upon, we found that acoustic wave velocities decrease with increasing TOC and increase with maturity.