Resistivity cutoff of low-resistivity and low-contrast pays in sandstone reservoirs from conventional well logs: A case of Paleogene Enping Formation in A-Oilfield, Pearl River Mouth Basin, South China Sea

Abstract Deep sandstone reservoirs in the Paleogene Enping Formation of A-Oilfield, Pearl River Mouth Basin, are significant offshore petroleum targets for this basin. Compared with adjacent water zones and shales, pays low resistivity contrast (LRLC). Without new unconventional well-logging techniques, conventional interpretation has encountered difficulties these LRLC pays. In article, based on Simandoux water–oil saturation equation, influence factors formation simulated theoretically. Resistivity cutoff is calculated at average reservoir conditions proved by oil-testing results. It applied to oil LWD, possible genesis discussed. pays, zone larger than cutoff; approximates lower threshold. At shale volume porosity Formation, referenced 4.2 Ω·m overall. reservoirs, A-Oilfield might result from high salinity, complicated pore-throat structure, well physical properties, presence conductive clay minerals. The offers important information real-time tracking LWD. proposed method demonstrated be beneficial identifying hydrocarbons monitoring trajectory