Study On The Microscopic Characteristics Of Shale Oil Reservoirs Of Shahejie Formaion In The Lijin Sag

The effective source rock of Es₃^xand Es₄^s segments in Lijin Sag has a broad prospect of shale oil exploration, with wide distribution, large thickness and strong hydrocarbon generation capability. Because the Es₃^xand Es₄^s segments in Lijin Sag have multiple types of rocks, strong heterogeneity, laterally fast-changed lithology,various types of reservoir space and their pore is micro-nanometer-level pore, a microscopic characteristics research of shale oil reservoir is needed.This paper analyzes the organic geo-chemistry characteristics of source rock in Es₃^x to Es₄^s of Lijin Sag by means of rock pyrolysis and organic measurement analysis experiment. It is believed that the content of TOC of source rock in our research area is high, which is generally above 2.0%. The amount of potential hydrocarbon?S1+S2?is mostly more than 10mg/g. Chloroform bitumen "A" value is concentrated between1% and 2%, with high organic material abundance. Shale organic materials are mainly kerogen I-II with high potential hydrocarbon generation capacity. Ro are concentrated between 0.5% and 0.9%, with proper maturity.Through analysis of petrology characteristics of Es₃^xand Es₄^s segments in research area by core observation, thin section identification and X-ray diffraction experiment, it is believed that the clay mineral of Es₃^xand Es₄^s segments in research area are mainly illite and montmor/illonite mixed layer, in clay mineral content, the average content of illite is 68.8%, the average content of montmor/illonite mixed layer is 26.5%. Carbonate minerals are mainly calcite, with 30.5% average content. Detrital minerals are mainly quartz, quartz content was 25.5% on average. Lithology are mainly calcareous mudstone, argillaceous limestone and calcareous mudstone, with content of 26.53%?21.94% and 14.29% respectively.Combining with field emission environmental scanning electron microscope,MIAS-2000 colored image analysis system and the nitrogen absorption/stripping experiment, this paper analyzed reservoir space types of Es₃^x and Es₄^s segments in research area, measured shale oil reservoir physical parameters, depicted the occurrence status of shale oil, and discussed the main controlling factors of shale oil reservoir physical property. It thinks that the main reservoir space types of Es3xandEs₄^ssegments in research area are intergranular pore and intergranular seam,accounting for 40% and 45% respectively, followed by dissolution pore, accounting for 8%, intergranular pore is less, only 2%, which has less contribution to oil and gas reservoir. Calcite, dolomite and intracrystalline hole are not connected with the outside world, where oil stains are not found, belonging to the invalid hole.The micro aperture above 50 nm of Es₃^x and Es₄^s segments in research area are mainly 500 to 800 nm. The nitrogen absorption/stripping experiment indicates that the aperture of micro pore below 50 nm distribute from 1.6 to 46.0nm, whose peak concentrate on 3⁶ nm. Shale oil in reservoir space are major film-shaped, round oil droplets are rare. The factors of shale oil reservoir physical properties are mainly the content of clay mineral and calcite, the clay minerals distribute scattered, irregular arrangement, easy to form a large number of intergranular pores, the recrystallization and cementation of calcite is not conducive to the development of the pore, the high content of clay mineral, the porosity is good, the high content of calcite, the porosity is poor.