Reservoir Characteristics Of Shale Oil In Shahejie Formation Of NiuZhuang Sag

Shale oil is the oil that is produced from shale beds(including other lithologic layers) of the source rock. The distribution of shale oil in Shahejie Formation is stable. The lithology of study area is mainly composed of argillaceous limestone and calcareous mudstone. Therefore, based on core and storage space experiment, by using modern analysis technology, we study the reservoir minerals, storage in space and stress sensitivity of the area. We obtain following understandings.Minerals in the study area are mainly composed of calcite, dolomite, clay minerals, quartz and minor minerals with potassium feldspar, plagioclase and pyrite and siderite ore. Overall, the calcite content is the highest of all.Mudstone reservoir space are mainly the pores and micro fractures between mud debris, limestone reservoir space includes dissolution pores and micro seam, and the number of dissolution pores is bigger than other two types, the space of dolomite reservoir is diverse, and dolomite pore with larger size is dominated.The main pores of limestone and mudstone samples from the study area are 2~10nm and 10~20nm, and the peak aperture is about 5~10nm. Dolomite sample mainly has the size of pores over 10 nm, and the aperture of the dolomite sample is larger than others.The shale oil samples of study area changes much smaller in porosity than permeability under covering pressure. Mud shale can flat strong under high pressure because of not only the micro cracks and pores but also the compressibility of clay minerals. Shale cores should stress sensitivity coefficient is generally higher than that of sandstone, and the mud shale shows strong stress sensitivity on the whole.