Pore structure evolution and geological controls in lacustrine shale systems with implications for marine shale reservoir characterization

• Published in: Scientific reports Vol. 15; no. 1; pp. 17702 - 14
• Main Authors: Li, Hu, Xu, Ziqiang, Gao, Xiaodan, Xie, Jiatong, Qin, Qirong, Wang, Haijun, He, Shun
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 21.05.2025; Nature Publishing Group; Nature Portfolio
• Subjects: 704/2151/213; 704/2151/3930; 704/2151/431; Adsorption; Clay; Comparative analysis; Connectivity; Diagenesis; Diagenetic controls; Engineering; Evolution; Experiments; Freshwater environments; Gases; Geology; Humanities and Social Sciences; Illite; Kerogen; Lacustrine shale; Lithology; Low temperature; multidisciplinary; Nitrogen adsorption analysis; Oil shale; Organic matter; Oxidation; Pore structure evolution; Reservoirs; Scanning electron microscopy; Science; Science (multidisciplinary); Sedimentation & deposition; Shale; Shale gas; Shale oil; Shales; Unconventional reservoirs; X-ray diffraction; Unconventional reservoirs; Lacustrine shale; Nitrogen adsorption analysis; Pore structure evolution; Diagenetic controls
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-025-02415-y

Understanding pore structure evolution in lacustrine shale systems provides critical insights for marine shale reservoir characterization. This study presents an integrated petrological and petrophysical analysis of a representative lacustrine shale succession, employing low temperature nitrogen adsorption (LTNA), whole rock X-ray diffraction (XRD), and scanning electron microscopy (SEM). The study shows that (1) Clay-dominated pore systems evolve through distinct pathways compared to marine shales, with illite/smectite mixed-layer minerals generating abundant mesopores through diagenetic transformation. (2) Organic matter- dominated pores display limited connectivity due to Type III kerogen characteristics and hydrocarbon generation-induced pore occlusion, contrasting with marine shale systems dominated by Type II kerogen. (3) Comparative analysis demonstrates that lacustrine shales preserve 30–40% higher micro-mesopore volumes than their marine counterparts under similar thermal maturity conditions, attributed to enhanced clay mineral diagenesis in freshwater environments. These findings provide a new framework for understanding pore structure development in non-marine depositional systems and provide valuable analogs for marine shale reservoir evaluation, particularly in transitional marine-lacustrine basins.