Pore structure and fractal characteristics of Wufeng–Longmaxi formation shale in northern Yunnan–Guizhou, China

In this study, the microscopic pore characteristics of shale in marine strata are evaluated. Based on field emission scanning electron microscopy (FE-SEM), low-temperature N 2 adsorption (LT-N GA), low-pressure CO (LP-CO GA) and high-pressure methane (HPMA) experiments, 12 shales from Wufeng–Longmaxi Formations northern Yunnan Guizhou characterized qualitatively quantitatively. Fractal Frenkel–Halsey–Hill (FHH) theory is used to analyse fractal characteristics, discussed. The correlation between dimension structure performance determined. results show that total organic carbon (TOC) contents middle–low level, ranging 0.43% 5.42%, generally highly mature overmaturity stage (vitrinite reflectance ( R o ) values 1.80% 2.51%). mineral composition mainly quartz clay minerals. average content 40.98% (ranging 24.7% 63.3%), 29.03% 16.8% 39.6%), which consistent with those Sichuan Basin. FE-SEM LT-N GA isotherms reveal a complex open style, ink bottle-shaped parallel plate-like pores. volumes (PVs) range 0.012–0.052 cm 3 /g, specific surface area (SSA) 18.112–38.466 m /g. All samples have abundant micropores mesopores, accounting for >90% SSA. dimensions, D1 D2, were obtained data, different at 0–0.5 0.5–1.0 relative pressures. dimensions increase increasing BJH PV BET SSA decrease decreasing diameter (APD). positively correlated TOC negatively content. can be evaluate capacity; larger is, capacity is. analysis helpful better understand gas reservoirs.