Hydrocarbon inclusions in the Ordovician in the Tazhong- Ⅰ slope-break zone can be divided into four episodes of development according to their fluorescence characteristics, intercalating relationship with calcite vein, and homogeneous temperature, and so on. Based on the tectonic evolution of the area, it is believed these episodes correspond to four episodes of hydrocarbon pooling： low maturity oil accumulation at the end of Silurian, oil generation in the late Hercynian, condensate oil and wet gas accumulation in the early Himalaya, and dry gas accumulation in the late Himalayan. The distribution of these four episodes of inclusions presents clear zonation in the Ordovician reservoirs in the Tazhong- Ⅰ belt. Four zones are recognized from the shallow oil reservoir in the southeast to the deep oil reservoirs in the northwest. It is suggested that the fossil oil from the episode Ⅲ and Ⅳ played a dominant role in the formation of present hydrocarbon accumulations.
Oil ＆ Gas Geology
fluorescence characteristic, pooling episode, Ordovician, hydrocarbon inclusion, Tazhong- Ⅰ slope- break zone