Structural characterization of porous media becomes extremely important in understanding the transport and storage phenomena in shale. Ultra-small angle x-ray scattering (USAXS) measurement has been performed on shale rocks from a wide range of depth, providing the insight into the nature of pore structure including pore size distribution, porosity, and specific surface area. Dehydrated shale samples were also employed and a comprehensive comparison was carried out to investigate the structural changes induced by thermal treatment. The pore-size distribution and porosity both in untreated and dehydrated shale rocks might be affected in response to the variation of depth. Mesoporous characteristic is dominant for the samples in the range of diameters from 25 to 104 �, while the increased number of pores in range of 2.5 -10 nm is notable with the dehydrated samples. The increased porosity after dehydration suggests that the water removal is an important contributor of the structural deformation of pores. The result also suggests that the specific surface area may be affected by the porosity values since the decreasing specific surface area was obtained as an increased depth both in untreated and dehydrated shale rocks. The geometric irregularities of pore-shale rock interfaces have been quantified by fractal dimension. An increased fractal dimension after the heat treatment suggests that the removal of water molecules increase the surface or mass irregularity.

Dehydration effect on pore size, porosity, specific surface area, and fractal parameters of shale rocks: USAXS study

248th National Meeting (2014)

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