塔里木盆地塔河地区奥陶系油气成藏期次差异性及其主控因素OA

Ordovician Tahe area in Tarim Basin is characterized by multi-periods accumulation and complex accu-mulation processes.Differences in oil and gas accumulation periods and their main controlling factors have not been revealed,which restrict the accurate understanding of oil and gas accumulation process.Based on previous re-search,comprehensive analysis of reservoir fluid inclusion petrography,microscopic fluorescence spectroscopy and microscopic temperature measurement is conducted to determine the differences in oil and gas reservoir accumula-tion periods and their main controlling factors in Ordovician Tahe area.The results show that 3 types of fluorescent colors of oil inclusions developed in Ordovician Tahe area,with significant differences in the main peak wavelength(λmax)and red-green entropy value(QF535).Based on the uniform temperature characteristics of associated brine in-clusions in oil inclusions,accumulation periods correspond to the Late Caledonian,Late Hercynian/Yanshanian and Himalayan periods,respectively.Tahe area has generally experienced 3 periods of accumulation,while only 2 periods of accumulation occured in the peripheral areas,with characteristics of the second period of oil and gas ac-cumulation lagged in the north and the main accumulation period gradually becoming earlier from south to north.Differences in structural evolution lead to different periods of oil and gas accumulation.Differential characteristic of secondary hydrocarbon generation of Cambrian source rocks,which is"earlier in the south and later in the north",is the fundamental reason for the lagging of the second period of oil and gas charging in the north.The spatial migra-tion of the main accumulation period is controlled by both mudstone caprock of Santamu Formation and Middle Cam-brian gypsum caprock.The research lays solid foundation for subsequent in-depth exploration.