Nanopore structures and controlling factors of the Early Cambrian shale reservoir in the Middle Yangtze Platform, South China

Fractal Characteristics of Nanopores and Their Controlling Factors of the Lower Cambrian Shale in the Western Hubei Area, South China

“…The PV mic and PV non-mic values are in the ranges of 0.0135–0.0629 cm 3 /g (average = 0.0360 cm 3 /g) and 0.0592–0.1924 cm 3 /g (average = 0.1172 cm 3 /g), respectively (Table ), which account for 62.48–89.41% (average = 75.79%) and 10.59–37.52% (average = 24.21%), respectively (Figure b), suggesting that the PV total values are mainly contributed from non-micropores. These pore structure characteristics of isolated kerogen samples are very similar to those of the corresponding whole-rock samples . Nevertheless, compared with the corresponding whole-rock samples, the proportions of SSA mic in SSA total and PV mic in PV total of the isolated kerogen samples are significantly higher and slightly lower, respectively, which further infers that the SSA total values are chiefly contributed from the OM micropores, whereas the non-micropores are mainly contributed from the shale IM.…”

“…Li et al reported the nanopore structure characteristics of whole-rock samples, and the pore structure of isolated kerogen samples was further measured in this study. The LPCA and LPNA isotherms of isolated kerogen samples are very similar (Figures and ).…”

“…As shown in Figure a, the quartz content of whole-rock samples is not obviously correlated with the D 1 values but positively correlated with the D 2 values to some extent ( R 2 = 0.25). According to Li et al, the relationship between TOC and quartz contents of whole-rock samples was not obvious, suggesting that the biogenic quartz content of the Lower Cambrian shale samples was small. Thus, quartz content has little influence on the roughness of shale pore surfaces but exerts a positive influence on the heterogeneity of the shale pore structure, which is consistent with the nanopore characteristics of the Upper Ordovician–Lower Silurian marine shale reported by Li et al In general, quartz has high hardness and strong compaction resistance, which is conducive to preventing pore collapse during burial compaction, , and some quartz grains are susceptible to sliding or rotating due to structural deformation.…”

“…Cross-plots of ln V N versus ln­[ln­( P 0 / P )] based on LPNA isotherms of whole-rock samples (data are from Li et al; adapted with permission from ref . Copyright 2023, Editorial office of Journal of Asian Earth Science).…”

“…Conventional pore structure parameters of shales mainly include pore size, pore size distribution (PSD), pore types, pore-specific surface area (SSA), and pore volume (PV). − A variety of techniques and methods has been applied to quantitatively characterize the shale pore structure, such as low-pressure CO 2 and N 2 adsorptions (LPCA and LPNA), high-pressure mercury injection (MICP), small and ultrasmall angle neutron scattering (SANS/USANS), and nuclear magnetic resonance (NMR). ,− In these methods, LPCA and LPNA experiments are usually applied to obtain PSD, SSA, and PV, which are effective in characterizing the shale pore structure. ,,− …”