(215h) Probing the Influence of Structural Changes on the Microstructural Evolution in Shale on Heating using Multi-Scale X-ray Scattering Measurements

Various pathways to accelerate the recovery of hydrocarbons from unconventional, nanoporous-rich subsurface environments have been proposed including the use of high temperature fluids. However, the resulting microstructural and structural changes in complex subsurface materials characterized by compositional and morphological heterogeneity are not very well understood. In this study, in-operando synchrotron multi-scale X-ray scattering analyses are used to determine the dynamic microstructural and structural changes in shale on heating from 30°C to 1150°C with complementary analyses of the changes in the porosity, particle size, and surface morphology. The detailed transformations of the constituents in shales including calcite, illite and quartz and the subsequent formation of denser crystalline phases such as Al_2.35Si_0.64O_4.82 (mullite), Mg₂SiO₄ (forsterite), and Fe_0.3Mg_0.7(SiO₃) (enstatite) are noted from the wide and small angle X-ray scattering measurements. The changes in the roughness of the pore-solid interface on heating are determined from the combined ultra-small and small angle X-ray scattering measurements.