Structural characterization of clays and other minerals in unconventional gas and oil resources becomes extremely important in understanding the transport and storage phenomena. Among clay minerals abundant in shale rocks, smectite is a key element in predicting fluid migration. The interlayer space of smectite can contain large amounts of water molecules and thus thermal treatment should affect their structure and physical properties. Ultra-small angle x-ray scattering (USAXS) measurements have been performed on five different cation (K, Na, Ca, Mg, Cs) - exchanged montmorillonite samples, providing the insight into the structural changes induced by in-situ thermal treatment up to 200 °C. The variation of pore-size distribution and morphological changes were observed and suggests that the water removal is an important contributor to the deformation of pore structures. Dehydration properties are also strongly related to their exchanged cations. Additional SAXS experiments revealed the thermal dehydration effects on basal spacing of montmorillonite samples, providing a clear view to the evolution of the interlayer sites during the dehydration process.

New insights into thermal effects of</b> K, Na, Ca, Mg, and Cs-exchanged montmorillonite </b>by in situ USAXS/SAXS study

249th National Meeting (2015)

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