Shale Reservoir Characteristics of the Lower 3th Member of Shahejie Formation,Luojia Area,Zhanhua Sag

The thickness of shale in the Lower 3th Member of Shahejie Formation,Luojia area,Zhanhua sag ranges100 ~ 300 m,which has a larger amount of oil and gas resources and exploration potential. Studies have shown that,the sedimentary environment of the shale is deep- semi-deep lake with high salinity,strong reduction; the rock types of the Lower 3th Member of Shahejie Formation,Luojia area,Zhanhua sag include mudstone,limestone,and the transitional types between them,content of carbonate is generally higher than 50%,according to the thickness,the combination way,different proportions and stability of the lamina,the rocks are divided into different types,the most important rock types are thin laminated- bedded argillaceous limestone. Reservoir porosity is 1.4% ~ 13.7%,average value is 5.3%,reservoir permeability changes significantly,general ranges from 1×10-3μm2to 10×10-3μm2,average value is 7.5×10-3μm2,which is low porosity and permeability reservoir,Reservoir fractures include tectonic fractures,micro- fractures between layers and diagenetic fractures,pores include minerals intergranular pores,dissolution pores and the organic matter micro-pores; reservoir properties are controlled by mineral composition and rock types,diagenesis,organic matter content and other factors,organic matter is a major internal factor that affects shale reservoir properties.