Comprehensive characterization of geological features and reservoir potential of high-quality shale of Wufeng-Longmaxi Formation in the north Guizhou dipping zone, South China

Amid global energy innovation, shale gas exploration is of great significance to China, and stratigraphic information research is paramount for its exploration and development. This study advances theoretical understanding of shale gas accumulation in northern Guizhou, thereby providing solid theoretical support for gas accumulation in the target area. We analyzed the mineralogical, geochemical, and petrological properties of a large number of organic-rich shale samples from the Wufeng-Longmaxi Formation in northern Guizhou. Analyses of the rocks' redox environment reveal that this formation was mainly deposited under anoxic conditions, with most shales being silica-rich and dominated by Type Ⅰ organic matter-confirming their marine origin. Integrating field investigations, experimental analyses, and well logging interpretation, we systematically evaluated the organic geochemical characteristics, reservoir performance, and gas content of shales in the study area. The results show that the Wufeng-Longmaxi shales have high total organic carbon (TOC, average 3.5%), high thermal maturity (vitrinite reflectance, Ro: 2.1%~3.4%), and favorable brittle mineral content (40%~65%), qualifying them as high-quality shale gas reservoirs with viable development potential, while substantial reserves and recoverable volumes of shale gas are predicted around the northern Guizhou syncline swarm. This study shows a high correlation with existing shale wells in the syncline-controlled area, and provides theoretical support for the exploration and accumulation assessment of undeveloped organic-rich shales of the Wufeng-Longmaxi Formation.