Chang9 oil layer of the Triassic Yanchang Formation is a key horizon for reservoir development in Jiyuan area

Ordos Basin.The characteristics of fluid inclusions in Chang9 reservoir in Jiyuan area were analyzed systematically based on the measurements of Fourier transform infrared spectroscopy

fluorescence spectroscopy

and homogenization temperature to determine

in combination with the burial-thermal history

the phases and periods of hydrocarbon migration and accumulation.The results show that there are two types of hydrocarbon inclusions in the reservoir of Chang9

namely liquid hydrocarbon inclusions and gas liquid hydrocarbon inclusions with green or yellow-green fluorescence.The homogenization temperature of brine inclusions associated with the hydrocarbon inclusions has a continuous distribution with a 100-120 ℃ peak value.Salinity distribution is relatively concentrated with a peak value of 3-5 wt%NaCl.These cha-racteristics indicate that there is one major phase of oil migration and accumulation in the study area.Consistently

fluorescence spectroscopy and Fourier transform infrared spectroscopy data demonstrate that the Chang9 reservoir has undergone one phase of hydrocarbon charging with high organic matter maturity

with yellow-green and green fluorescence

corresponding to the fluorescence spectrum of 495nm.The analysis of burial and thermo-evolutionary history of Chang9 oil layer show that the hydrocarbon charging occurred mainly in mid-late stage of the Early Cretaceous.