Microscopic Pore Type And Controlling Factors Of The Shale Reservoir Of The Shahejie Formation In Zhanhua Sag

Zhanhua Sag is the most promising area for shale hydrocarbon reservoirs in Jiyang Depression,Bohai Bay Basin.Lots of researches had been made on shale reservoir,but it is still weak on the microscopic pore classification and controlling factors.This paper researched the mineral components,the microscopic pore types and their controlling factors of shale reservoirof the Shahejie Fomation.It is significant for defining the distribution of the shale hydroncarbon resources and improving teh efficiency of exploration and development in the study area.Based on core analysis,thin sections,cathodoluminescence,SEM and X-ray diffraction tests,the shale is mainly composed of calcite,clay minerals,dolomite,quartz and pyrite.The types of clay minerals mainly containes illite smectite mixed mineral,illite and kaolinite.The microscopic pore classification of shale of Shahejie Formation of Zhanhua Sag has been put forward.The reservoir space of the shale reservoir is divided into pore and fracture.The pore includes intergranular pore,intragranular pore and organic-matter pore.The fracture includes interlaminar crack,tectonic fracture,diagenetic fracture and organic-matter shrink crack.The shale microscopic pore is measured by tests of isothermal nitrogen adsorption,isothermal carbon dioxide adsorption and high pressure mercury injection.The mesopores are most in the shale of the Shahejie Formation.Five controlling factors of the shale microscopic pore are analysised.Early sedimentary environments and tectonic background control the mineral composition of shale,the types of kerogen and others factors.And they indirectly control the shale microscopic pore.Different lithology and mineral composition have different pore structure.Total organic carbon controls organic matter pores,and then controls the development of the shale pore structure.Kerogen types directly control the pore evolution.Finally with the diagenesis and thermal evolution aggravating,micropore and mesopore rise slowly after falling.Macropore is inversed,namely,falling slowly after rising.Organic matter pore continues to increase until the peak.