Correlative Multiscale Imaging of Mancos Shale

Abstract

Abstract Mudstone (shale) reservoir evaluation and efficient development poses a significant challenge due to the heterogeneous nature of these complex formations. Organic-rich shales are characterized by intricate mineralogy, ultra-low nanoporosity, and nano-darcy permeability making these tight source/reservoir rocks challenging in obtaining economically viable hydrocarbons. Consequently, characterizing and quantifying minerology and intra-/interparticle (non)organic-hosted porosity at the pore-scale, and up-scaling it to the core-scale remains a significant focus of evaluating reservoir quality in shale plays. Current advances in correlative multi-scale and multi-modal 2D/3D imaging of nanoporous geomaterials, such as shales, provide a tremendous opportunity to characterize and represent these rocks over multiple length scales – from core-to pore-scale. Subsequently, these image datasets can be then used for advanced image analysis and digital rock modeling to reconstruct 2D/3D models used to analyze their petrophysical properties. In this study, the Mancos Shale from the Uinta Basin – one of the most promising shale plays in the United States (Hawkins et al. 2016) – was characterized from centimeter-to nanometer-scale via digital rock analysis using correlative micro 3D X-ray computed tomography (micro-CT), micro 3D X-ray microscopy (micro-XRM), light microscopy (LM) mosaic map, scanning electron microscopy (SEM) mosaic map, and focused ion beam (FIB) – SEM (FIB-SEM) nano-tomography image datasets. These multi-resolution and multi-dimensional image datasets, were then registered with each other, and used to reconstruct digital rock 2D/3D models from which shale petrophysical properties such as lithology, mineralogy, and porosity were extracted. Additionally, the imaged mineralogy and porosity results were compared with traditional laboratory experimental data, such as XRD and helium porosity measurements.