Enlightenment of geochemistry for ultra-deep petroleum accumulation: Coupling of secondary processes and filling events

作者：Rongzhen Qiao, Meijun Li, Donglin Zhang, Hong Xiao · 发表于：Petroleum Science · 年份：2025 · DOI：10.1016/j.petsci.2025.02.019 · 被引用次数：4 · 研究领域：Hydrocarbon exploration and reservoir analysis、Atmospheric and Environmental Gas Dynamics、Geochemistry and Geologic Mapping

Light oil and gas reservoirs are abundant in the Ordovician marine carbonate reservoir in Shunbei Oilfield, Tarim Basin. This presents a compelling geological puzzle, as ultra-deep reservoirs undergo intense alteration and complex petroleum accumulation processes. A comprehensive suite of geochemical analyses, including molecular components, carbon isotope composition, homogenization temperature of saline inclusions, and burial-thermal history of single wells, was conducted to elucidate the genesis of these ancient reservoirs. Three petroleum filling events have been identified in the study area: Late Caledonian, Hercynian-Indosinian, and Himalayan, through analysis of homogenization temperatures of brine inclusions and burial-thermal histories. Additionally, the oil in the study area has undergone significant alteration processes such as biodegradation, thermal alteration , mixing, evaporative fractionation, and gas invasion. This study particularly emphasizes the influential role of Himalayan gas filling-induced evaporation fractionation and gas invasion in shaping the present petroleum phase distribution. Furthermore, analysis of light hydrocarbon and diamondoid parameters indicates the oil within the study area is at a high maturity stage, with equivalent vitrinite reflectance values ranging from 1.48% to 1.99%. Additionally, the analysis of light hydrocarbons, aromatics, and thiadiamondoids indicates that TSR should occur in reservoirs near the gypsum-salt layers in the ...