Simulation On Generation And Occurrence Of Shale Oil In Source Rocks Of Third Member Of Shahejie Formation In Luojia Area

High-quality hydrocarbon source rocks of the third member of Shahejie formation in Zhanhua sag are extensively distributed and of large thickness,high abundance of organic matter,good types and high evolution degree.Zhanhua sag has the material basis for the formation of shale oil and gas.Block,layered and grain layer representative hydrocarbon source rock samples are choosed for simulation experiment,fluorescence chip and environmental scanning electron microscopy(sem)analysis to explore the difference of different lithologic hydrocarbon expulsion efficiency,the quantity and composition of discharge and retention oil,the reservoir space and occurrence of retention liquid hydrocarbon.A preliminary evaluation on the formation and occurrence of shale oil of the third member of Zhanhua sag will be done.Through hydrocarbon expulsion simulation experiment,fluorescence thin sections and environmental scanning electron microscope,differences of the process of hydrocarbon expulsion of different lithologic hydrocarbon source rock,eduction and retention of liquid hydrocarbon and liquid hydrocarbon reservoir and the occurrence are found.Oil production rate,retention hydrocarbons and discharge oil production rate showed a trend of decrease after the first increase with increasing simulated temperature of the three different types of hydrocarbon source rocks.For the grain layer source rocks,retention hydrocarbon yield is significantly greater than the discharge of oil between the value of Ro from 0.7% to 1.0%,with retention rate/discharging rate maximum 5.37(Ro = 0.8%);in the early period of oil production stage,oil fractionation phenomenon is obvious with more light component in discharge oil than in retention oil;micro cracks between the layers are major reservoir space for the entrapped liquid hydrocarbon and width increases with the increase of maturity;intergranular hole seam calcite and quartz,pyrite,clay mineral intercrystal pore can also be reservoir space for a certain amount of liquid hydrocarbon.For the layer source rocks,retention hydrocarbon yield is significantly greater than the discharge of oil between Ro =0.7%~0.9%,with retention rate/discharging rate maximum when Ro=0.7%;Layered hydrocarbon source rocks between the value of Ro from 0.7% to 0.9% retention hydrocarbon yield was significantly greater than the discharge of oil,retention rate/discharging rate values in Ro = 0.7% when the highest;discharge oil contain more light component in the early stages of oil production,but oil fractionation phenomenon is not obvious compared with grain layer hydrocarbon source rock;calcite edge cracks,pyrite,baiyun imitations and clay mineral pores are main reservoir space for stranded liquid hydrocarbon,and crack formation is very obvious.For the block source rocks,retention hydrocarbon yield is greater than the discharge of oil only when Ro is 0.7%;there is no significant difference of component between discharge oil and retention hydrocarbon;with the increase of evolution degree,the rock cracks,stranded liquid hydrocarbon mainly distributes in the fracture associated with hydrocarbon generation and other liquid hydrocarbon decentralizes in clay mineral pores.Depending on the the hydrocarbon generation process of different type source rocks,combined with the organic matter evolution section of the third member of Shahejie formation in Luojia area,following conclusions are got:the most favorable maturity of block,layered and grain layer source rocks are 0.7% ~ 0.9 %,0.7%~ 1.0% and 0.8% ~1.1% respectively,corresponding to the depth of section 3300~3600m,3300~3800m and 3600-4000 m.Due to the low organic carbon content and enrichment degree,block source rocks is not very conducive to the formation of shale oil.