Pore Structure and Fractal Characteristics of Kelasu Ultra-Deep Tight Sandstone Gas Reservoirs

作者：Liandong Tang, Yongbin Zhang, Xingyu Tang, Qihui Zhang, Mingjun Chen, Xuehao Pei, Yili Kang, Yiguo Zhang, Yuting Liu, Bihui Zhou, Jun Li, P C Tian, Di Wu · 发表于：Processes · 年份：2025 · DOI：10.3390/pr13103074 · 被引用次数：4 · 研究领域：Hydrocarbon exploration and reservoir analysis、Hydraulic Fracturing and Reservoir Analysis、NMR spectroscopy and applications

Ultra-deep tight sandstone gas reservoirs are key targets for natural gas exploration, yet their pore structures under high temperature, pressure, and stress greatly affect gas occurrence and flow. This study investigates representative reservoirs in the Kelasu structural belt, Tarim Basin. Porosity–permeability were measured under in situ conditions, and multi-scale pore structures were analyzed using thin sections, a SEM, mercury intrusion, and nitrogen adsorption. The results show that (1) the median permeability of cores at an ambient temperature and a confining stress of 3 MPa is 13.33–29.63 times that under the in situ temperature and pressure conditions. When the core permeability is lower than 0.1 mD, the stress sensitivity effect is significantly enhanced; (2) nanopores and micron-fractures are well developed yet exhibit poor connectivity. The majority of a core’s porosity is derived from the intergranular pores in clay minerals; (3) the volume of nano-sized pores within the 100 nm diameter range is mainly composed of mesopores, with an average proportion of 73.37%, while the average proportions of macropores and micropores are 22.29% and 4.34%, respectively; (4) full-scale pore sizes show bimodal peaks at 100–1000 nm and >100 μm, which are poorly connected; (5) the pore structure exhibits distinct fractal characteristics. The fractal dimension Df1 (2.65 on average) corresponds to the larger pore diameters of the primary intergranular pores, residual intergranular...