Reservoir characterization and exploration potential of shale reservoir near denudation area: A case study of Ordovician–Silurian marine shale, China

Abstract The distribution of denudation areas has brought huge risks to the exploration and development of deep buried shale gas resources. The reservoir characterization and exploration potential near denudation areas is of great significance to the evaluation of hydrocarbon favorable areas. In this study, we integrated total organic carbon content, X-ray diffraction mineralogical composition, scanning electron microscope, elemental geochemistry, and low-temperature N 2 adsorption to characterize macro-reservoir parameters and micropore structure. Based on the abundant experimental data presented above, the origin of the pay zone in the near denudation area is clarified, and the exploration potential is addressed. The vertical variation characteristics of shale reservoir parameters near the denudation area are consistent in other regions and are controlled by global sea level changes. The main production layer is Longmaxi Formation 1st Section–Wufeng Formation. Compared to commercial pay zone of other areas, gas-rich shale near the denudation area has the characteristics of high porosity and high content of carbonate minerals. The large amount of carbonate minerals provides a material basis for the development of inorganic pores (dissolution pores and intergranular pores), making the shale near the denudation area have a larger mesoporous pore volume, and thus forming a high-porosity reservoir. The shale reservoirs near the denudation area in the study area have a high content of brittle minerals, which is conducive to hydraulic fracturing. The stable structural conditions are beneficial to the preservation of shale gas. Therefore, they have good exploration and development potential.