Application of the Discrete Element Method to Study the Effects of Occlusion Interfaces in Shale

Abstract

The multiscale heterogeneity of ultratight shale rocks leads to the interesting yet pragmatic question of whether or not its microscale features may be used to predict macroscopic fracture behavior. Understanding the dominant parameters of microfracturing in these structures may help both with understanding the evolution of macroscopic fractures as well as permeability changes in shales. While many macroscopic analogs exist to correlate shale composition with fracture properties, few studies have examined the role that shale microstructure has on fracturing.

In this thesis, I first describe the method I developed to use SEM/EDS data from shale images to set up discrete element method simulations. I then explore the role of shale microstructures under standard uniaxial fracturing and what effect it may have on macroscopic material properties and if there is a special role that interfaces between different materials may play during fracturing in shales. Using the data provided and the simulation results, I demonstrate the qualitative role that the interfaces between different materials play during both compressive and tensile fracturing.