Abstract: Minfeng sub-sag is a prospective area for lithologic reservoir exploration. 15 core samples from the Es 3 member of 8 wells are collected and prepared for fluorescence microscopy analysis of oil inclusions, petrographic characterization and microthermometry of oil and aqueous inclusions, and thermodynamic modeling of palaeopressure. The integrated results indicate that lithologic reservoir in this member underwent three periods of hydrocarbon charging events that happened during (28~25)×10⁶ a, ( 7.1~3.4)×10⁶ a and 1.1×10⁶ a, dominated by late event since 7.1×10⁶ a. The thermodynamic modeling results show that three cycles of pressure increase and decrease since the sedimentation of Ed formation are of coupling relationship with the three periods of hydrocarbon charging events. The first charging featured at normal pressure; the second one at abnormal pressure and the third one was divided into two states: the early dominated by abnormal pressure; the late dominated by normal pressure.

Key words: Minfeng sub-sag, lithologic reservoir, hydrocarbon charging event, fluid inclusion, palaeopressure