Core observation

thin section identification

X-ray diffraction

physical property and organic matter testing are integrated to reveal the mineral composition

physical properties

organic matter and lithology of the shale oil reservoirs in the Lower 3

rd

Member of Shahejie Formation in Zhanhua Sag

the Bohai Bay Basin.And the characteristics of pore types and structure and their influences on reservoir property are analyzed by using Argon-ion milling and scanning electron microscope (SEM) technique.The mineral compositions of the target strata are dominated by clay

carbonate and terrigenous clastics.Both the porosity and permeability are low.The kerogen belongs to type I with high total organic carbon (TOC) content in the range of 0.52%~9.32% and vitrinite reflectance (R

o

) in the range of 0.7%~0.93%.The lithologies are dominated by argillaceous limestone

limy mudstone and mud bearing limestone

with minor limy dolomite.With Argon-ion milling and SEM method

we studied 10 core samples from Well Luo 69 via qualitative analysis and quantitative statistics.According to the pore characteristics

pores can be divided into micropores and microcracks.The micropores can be further subdivided into intergranular pore

intercrystalline pore

dissolved pore and intracrystalline pore.The microcracks

dissolved pores

large intercrystalline pores and intergranular pores provide the main reservoir space for the shale oil reservoir.Pore types and distribution vary with different reservoir lithologies

which control the reservoir storage capacity.The limy dolomite is the best in storage capacity

followed by limy mudstone

argillaceous limestone and mud bearing limestone

and the limestone is the least.