FISH Seminar – "Shales And Imposters: Understanding Shales, Organics, And Self-resourcing Rocks"

Friday September 7, 2012 8:00 am

Abstract: Shales are very commonly occurring sedimentary rocks. They are alternatively described by grain size (less than 2 micrometers), mineralogy (hydrous aluminosilicates), or sedimentary features (fissile, fine-grained, and clay-rich). The presence of clay minerals, hydrous aluminosilicates that are smaller than 2m can alter the elastic and plastic behavior of materials significantly. Load-bearing clays form weak links between the stronger mineral components. Knowledge about the elastic properties of clay is therefore essential for the interpretation and modeling of the seismic response of clay-bearing formations. However, due to the layered structure, small grain sizes, and reactive nature of clay minerals, their elastic properties are poorly known and show large differences (between 10 GPa and 400 GPa) between theoretical and measured values of clay moduli. This discrepancy is mainly due to various amounts of water adsorption by the clay minerals: Clay minerals are very reactive. Free radicals, such as hydroxyls, can alter their physical properties. I will discuss applications of rock physics and experimental data to calibrate observations made in the field, analyze experiments results on shales in controlled environment, and show various petrophysical controls on seismic properties, for example, on porosity, permeability, cementation, pore-filling, saturation, and compaction.

Event Contact

Thomas Gallott