Determination Of Shale Microstructure From Laboratory Data On Permeability

The permeability of three shale samples is measured in laboratory at the conditions similar to in situ (confining pressure is 41.4 MPa and pore pressure is 20.7MPa). The effective medium theory is applied to invert parameters of shale microstructure from these measurements. Shale is modeled as a patched medium consisting of two types of patches related to (1) mineral matrix (2) pores and cracks. A double-porosity model is used to describe the pore/crack geometry of shale, which takes into account a degree of pore/crack connec - tivity. The inverted parameters of shale microstructure are used to predict the elastic wave velocities and thermal conductivity at in situ conditions in different directions relative to the bedding plane. The predicted values of velocities are in good correspondence with the velocities provided by sonic logs and laboratory data. The inverted permeability of “mineral matrix” and “fluid” patches can be used for theoretical prediction of the permeability tensor for shale having sim ilar mineral composition and microstructure at the scale of laboratory