Integrated fluid inclusion analysis and petrography constraints on the petroleum system evolution of the central and southern Biyang Sag, Nanxiang Basin, Eastern China

摘要

We combine integrated fluid inclusion analysis, petrography, and burial-thermal-hydrocarbon generation history modeling, to delineate multiple generation-expulsion-charge episodes within the central and southern Biyang Sag, Nanxiang Basin, Eastern China. Basin models suggest the main phase of oil generation occurred between the late Eocene and early Miocene. This period generally corresponds to the three oil expulsion episodes (ca. 37.5 Ma, 33.1 Ma, and 23.0 Ma) recorded in petroleum inclusions that are hosted in fibrous calcite veins in organic-rich shales. Based on fluorescence spectrum parameters and the API gravities of a set of crude oils used as a calibration, the oils expelled during the three expulsion episodes were determined to have been heavy, black and light oils. Fluorescence correlations indicate that the three types of oil inclusions found in the source rocks correspond well with those detected in the reservoirs.