Characteristics Of Fluid Inclusions And Hydrocarbon Accumulation Periods Of The Es3 Reservoirs In The Chunliang Structural Zone

The Chunliang structural zone in the Dongying Depression contains a lot of fault block oil reservoirs.Because of its particular geological characteristics,the hydrocarbon accumulation rules became complex.The reservoir of the third member of the Shahejie Formation(Es3)is the main research object in this paper.Based on the study of diagenetic characteristics?petrography analysis of fluid inclusion and the observation of hydrocarbon inclusions by the fluorescence microscope,reservoir sandstone samples from well Chun 51 and well Liang 28 were selected as the main research object,and the homogenization temperatures of aqueous inclusions and coeval hydrocarbon inclusions from these sandstone samples were measured by the microthermometry microscope.Obtain the volume ratio of liquid to gas of the hydrocarbon inclusions by scanning them using the confocal laser scanning microscope,then determine the forming conditions of fluid inclusions through PVTsim and the method of intersecting isochoric lines of aqueous inclusions and coeval hydrocarbon inclusions.And analye the molecular composition of hydrocarbon inclusions to research the accumulation period in detail.Study shows that hydrocarbon inclusions were mainly trapped in the sealed fractures of quartz grains and the cracks through the quartz grains in the reservoir samples of Es3,and most of them have pale yellow fluorescence.By correcting,the trap temperature of hydrocarbon fluid that filled the reservoir of Es3 is between 118 ~oC and143 ~oC,and the trap pressure ranges from 183 bar to 259 bar.Gas chromatography mass spectrometry(GC-MS)analysis of hydrocarbon inclusions and crude oils show that they have the similar molecular compositions,crude oils and inclusion oils collected from well Chun 51,correlate well with the source rocks of Es4,while those collected from well Liang 28 were related to the source rocks of Es3,demonstrating that the crude oil and inclusion oil derived from single source rock.Moreover,combined with the burial history,there was only one hydrocarbon charging event in the Es3 reservoir of the Chunliang structural zone,and this process occurred from the Late Neogene to the Quaternary(4 Ma-0 Ma).