Quantitative Analysis of the Pore Structure of Premature-To-Postmature Organic Rich Mudrocks Using Small Angle Neutron Scattering

Abstract

The pore structure of organic rich mudrocks is associated with both inorganic and organic constituents. The contribution of organic matter to the pore structure has been investigated on Posidonia and Bossier Shale samples having different organic carbon content and thermal maturity. Development and distribution of organic matter pores were studied by using small angle neutron scattering technique at a broad pore scale size investigation, from 2 nm to 2 µm. The pore structure of the mudrocks studied is highly complicated at which total pore volume and specific surface area are not significantly affected by thermal maturation, however, the maturity attribute contributes to different pore size distribution on meso- and macro-pores. Thermal maturation is likely to be the factor of amalgamating small organic matter pores into larger pores in overmature organic rich mudrocks, potentially causing an increase in pore volume at macroscale pores. Although not considerably, the increased macroporosity can enhance the permeability of pore network for viscous gas flow in organic rich mudrocks.