Investigation of pore structure characteristics in marine deep-water high-temperature and high-pressure sandstone: A comprehensive characterization combining various experimental techniques

Marine deep-water high-temperature and high-pressure (HTHP) reservoirs have excellent potential for future oil and gas exploration. Because reservoir quality is often influenced by pore structure, understanding the charac-teristics of pore structures is essential for efficient exploitation. Therefore, it is necessary to conduct a comprehensive study of the pore structures in HTHP reservoirs. This study selected samples of the Enping Formation in the South China Sea as the research target and investigated the reservoir pore structures based on scanning electron microscopy, casting thin section, nuclear magnetic resonance, and mercury intrusion (e.g., high-pressure, constant-rate). The results show that the pore geometry and throat radius of different pore types in these reservoirs can lead to pore system heterogeneity. A comprehensive experimental method combining NMR and mercury injection was used to determine pore structure characteristics. In addition, a new pore size clas-sification scheme was developed for marine deep-water HTHP reservoirs, and the controlling effect of pore type on percolation flow capacity was analyzed. This study systematically used a comprehensive pore structure characterization method that combined various experimental techniques to present the pore structure and develop a new pore size classification scheme for deep-water HTHP sandstone reservoirs, providing insight into the reservoir quality of marine deep-water HTHP sandstone reservoirs.