A critical review on pore to continuum scale imaging techniques for enhanced shale gas recovery

Imaging and image analysis of shale provides insights into the pore and fracture networks, disposition of compositional elements, and signatures of diagenesis and fluid flow. Extraction of features and reconstruction to get highly accurate models of shales using image analysis involves various techniques and tools. The present paper reviews different 3D and 2D imaging methods, their advantages, and limitations, along with recommendations on making the most appropriate choice for visualization of desired features and their applications. While fractures and other elements of deformation can be well resolved using X-ray CT, the FIB-SEM is a better suited 3D imaging tool for resolving the nano-scale pore attributes of shale. Among 2D imaging methods, TEM can provide direct information on the micropores (