Pore Structure Characteristics and Genesis of Low-Permeability Sandstone Reservoirs in the Eocene Wenchang Formation, Huizhou Sag, Pearl River Mouth Basin, Northern South China Sea

Porosity and permeability are critical parameters in petroleum exploration and development. The relationship between pore structure and permeability in near-source reservoirs is more closely correlated than in other types of reservoirs. This study investigates the pore structure and formation processes of low-permeability sandstone reservoirs in the Wenchang Formation, Huizhou Depression, Pearl River Mouth Basin (Northern South China Sea). We collected ten core samples of low-permeability sandstone reservoirs at various depths from the key well (A). Multiple analytical techniques were employed, including mercury intrusion capillary pressure (MICP), constant velocity mercury injection (CMI), Wood’s metal impregnation (WM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and quantitative evaluation of minerals via scanning electron microscopy (QEMSCAN). Pore-throat types were classified using fractal theory, followed by analyzing the physical and structural characteristics of interconnected pore-throat reservoir systems. This study examined the impact of various pore types on the physical properties of reservoirs, providing a comprehensive classification and characterization of pore structures in low-permeability sandstone reservoirs. Our findings provide significant insights and recommendations for future developmental initiatives in this region.