Geological Boundaries Of Shale Oil Enrichment In The Lower Third Member Of Shahejie Formation In Zhanhua Sag

It is meaningful for favorable area optimization and resource potential evaluation to study the geological boundaries of shale oil enrichment.In this paper,based on a series of research on the geology,geochemistry,physical property,pore structure and oil-bearing,an indicator is established to evaluate the enrichment,and then the geological boundaries are defined,which both are suitable for the research area.The study shows that there are mainly four shale lithofacies,which are laminated argillaceous limestone,layered calcareous shale,layered argillaceous limestone and layered clay-bearing limestone.The average of TOC is 2.99%,organic matter is mainly Ⅰ,Ro is 2.59%,respectively.The effective source rock is the material basis of shale oil enrichment.The calcite that largely increases porosity has the most content of mineral compositions,which is 53.5% on average.The shale has a average brittleness index of 79.5%,average porosity of 2.28% and permeability of 2.0×10-6mD,the physical property of the deep shale is better than the shallow one,the high brittleness and better physical property provide good reservoir condition for shale oil enrichment.In the shale,intergranular pores between calcites and dissolved pores in the organic matter-mineral complexes are mainly distributed,the pore diameter increases with depth,and the macropore and mesopore contribute the most pore volume,which both are main places for shale oil,the development of micropores and microfactures and bigger pore diameter are the main spaces of shale oil enrichment.In above,the boundaries of shale oil enrichment are that the thickness is more than 30 m,depth is deeper than 2845 m,and the S1 is greater than 2mg/g,the ratio of S1 to TOC is greater than 100,Ro is greater than 0.85%,and the porosity is higher than 5.2%,the permeability is higher than 4.025×10-6mD,the oil saturation is higher than 40%,and the pore diameter exceeds 125 nm.