In the Luzhou Block of the southern Sichuan Basin, the deep Longmaxi shales have become important exploration targets in recent years. However, the water-bearing properties of these shales are still unclear, which significantly limits evaluations of reservoir pore structures and gas-in-place (GIP) contents. In this study, twelve fresh shale core samples were collected at the well site, and the pore water (C_PW) and equilibrium water (C_EW) contents, as well as the pore structures of the shales, were analyzed under both as-received and dried conditions. The results indicate that the deep shales have low water-bearing extents with a pore water content (C_PW) of 3.82–16.67 mg/g, and that both the organic matter (OM) and inorganic matter (IM) pores can be used for pore water storage. The extent of influence of pore water on nonmicropores and IM pore structures is more significant than that on micropores and OM pore structures. Meanwhile, the pore water obviously reduces the retention effects of nanopores and may block nanopores with pore widths < 0.5 nm. An average of 40% of pore spaces were taken up by pore water in the studied deep shales in the Luzhou Block, and the residual pore surface area and pore volume of the shales were mainly contributed from micropores and nonmicropores, respectively.

The deep Qiongzhusi (QZS) shales in the Deyang–Anyue Aulacogen, Sichuan Basin, are important shale gas targets in China. However, the differences in pore development of the shales in the marginal areas of the aulacogen and its main controlling factors remain unclear. In this study, the organic and inorganic compositions, water-bearing characteristics, and porosities of the sublayer 7 (SL7) and sublayer 5 (SL5) deep QZS shales collected from Well Z204 were systematically investigated. The results indicate that, compared with the SL5 shales, the SL7 shales have higher total organic carbon (TOC) and clay mineral contents, lower brittle mineral contents, greater porosities, and water content and saturation. The TOC content of the deep QZS shale has a strong positive correlation with porosity, and a negative correlation with water saturation. Therefore, the TOC content is the main controlling factor for the development of effective porosity. The TOC content of the SL7 shale is higher than that of the SL5 shale, so the SL7 shale has a larger effective porosity. Therefore, the margin of the Deyang–Anyue Aulacogen is a new exploration area for the deep QZS shales, and the shale gas accumulate conditions of the SL7 shales are better than that of the SL5 shales, especially in the lower section of the SL7 shales. This new understanding provides an important geological basis for the next exploration of the Deyang–Anyue Aulacogen.