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In recent years, significant efforts have been directed towards extracting deep shale gas (SG) in Luzhou. Understanding the factors influencing the accumulation and preservation of SG in the section extending from the Upper Ordovician Wufeng (WF) Formation (Fm) through the Lower Silurian Longmaxi (LMX) Fm is crucial for its large‐scale, profitable development. The shale layers in the LMX Fm located in the Luzhou‐Zigong area in the southern part of the Sichuan Basin have undergone unique geological processes, including deep deposition, intensive uplift, erosion and deformation. The Luzhou block, situated in the low‐fold zone in southern Sichuan between the southern slope of the paleo‐uplift in central Sichuan and the down‐warping fold zone in south‐eastern Sichuan, was studied using seismic, well‐log, drilling and core analysis and test data to understand its tectonic, sedimentary, reservoir and fracture characteristics and identify the principal factors controlling gas accumulation in this area. The study found that SG in the Luzhou block is primarily distributed in the WF Fm through the Longyi1 sub‐member. Class I continuous reservoirs, 2.6–20.3 m in thickness, are mainly found in the Longyi11–13 sublayers and those with large continuous thickness produced high yields during tests. Gentle anticlinal zones and wide, gentle tectonic structures with relatively high‐pressure coefficients have formed in this area. High‐angle fractures (HACs) in this area tend to accumulate free gas and, therefore, facilitate the accumulation and production of SG. The study concludes that the continuous thickness of Class I reservoirs and natural HACs controlled by the centre of the deep‐water continental shelf are the primary factors controlling SG accumulation in the Luzhou block. [ABSTRACT FROM AUTHOR]

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 (CPW) and equilibrium water (CEW) 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 (CPW) 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. [ABSTRACT FROM AUTHOR]