2025/10/01 by Zhanlei Wang, Ruiqian Zhao, Licheng Yang +5 · 1 voice
Engineering · Earth and Planetary Sciences · #Hydrocarbon exploration and reservoir analysis #Geological formations and processes #Geological and Geophysical Studies
paper · doi:10.1016/j.ngib.2025.09.001
openalex publication_date 2025/10/01 · openalex created_date 2025/10/12 · openalex updated_date 2026/07/02
The Wufeng-Longmaxi marine shale in the Eastern Sichuan Basin is the key target for shale gas exploration in China. Based on logging response and lithofacies type, three paleo-geomorphological units are identified in the deep-water shelf during the Wufeng-Longmaxi deposition: subaqueous slope (SS), subaqueous plain (SP), and subaqueous sub-sag (SSS). Using methods such as mercury intrusion porosimetry (MIP), field emission scanning electron microscopy (FE-SEM), nuclear magnetic resonance (NMR), and X-ray diffraction (XRD), the differences of environmental conditions, mineral composition, organic matter (OM) content, and pore structure in different units are determined, and the factors controlling the differences in shale reservoirs are discussed. The results show that redox conditions of bottom water and productivity of surface water affect OM enrichment, resulting in SSS being the most organic-rich unit. Terrigenous detrital input affects mineral composition in different units, and SSS is the most quartz-rich unit. From SS to SSS shale, the proportion of OM pores gradually increased, while the proportion of inorganic pores and microfractures gradually decreased. The pore size distribution dominated by mesopores in SP and SSS shale is generally consistent, much higher than in SS. The differences in sedimentary environments result in differences in reservoir quality. The OM and brittle mineral content in SSS are relatively high, which is beneficial for reservoir development. SSS has the best environmental conditions; therefore, the quality of the marine shale reservoirs formed is the best.