Reservoir Evaluation Of Chang 8 Oil-bearing Formation In Zhoujiawan Area,Ordos Basin

The main content of the thesis is heterogeneity,sorting appraise and select favorable exploration area of Chang 8 reservoir,Zhoujiawan area.Interlayer heterogeneity,in layer heterogeneity and plane heterogeneity are contained in the macroscopic heterogeneity.Porosity,permeability,coefficient of variation et al are calculated according to well logs so that we can study the macroscopic heterogeneity of the reservoir.In the aspect of microscopic heterogeneity,the experimental methods are being used.Many parameters can be studied according to the analysis of pressure mercury method,casting thin sections,scanning electron microscopy,X diffraction and series of routine analysis,just like rock types,pore and throat characteristic and so on.And these data can be used for analyzing digenesis of the reservoir.According to the analysis of macroscopic and microscopic heterogeneity to the reservoir,some conclusions can be obtained:(1)The studying area has a stronger characteristic in macroscopic heterogeneity,and the reservoir which has good physical properties are located in the main channel of meandering and braided river,and generally speaking,non-reservoir is found in the area of distributary channel.(2)In microscopic scale,the detrital composition of the rocks is mainly composed of terrigenous clastic,which has a high level in unstable components.And its composition is mainly feldspathic lithic sandstone and lithic arkose.Lithic arkose has a higher level than feldspathic lithic sandstone.The rocks are characterized fine sandstone and siltstone,only a few medium-grained sandstone,and has a low value in porosity and permeability.Overall,the reservoir belongs to ultra low porosity and permeability reservoir in studying area.(3)The intergranular pores,feldspar dissolution pores,micro-cracks et al are contained in the reservoir according to the analysis of casting thin sections.But most of the pores in therocks are composed of intergranular and feldspar dissolution pores.It can be divided to three categories by using of pressure mercury data:(A)Type of low displacement pressure-medium-fine throat;(B)Type of medium displacement pressure-fine throat;(C)Type of medium displacement pressure-micro throat.(4)In the process of classification to the reservoir,two methods are used:qualitative and quantitative.The qualitative method is commonly used.In the thesis we mainly according to the Changqing oil field standard,and combined with the actual situation of Zhoujiawan area.The gray association method is being used in quantitative analysis,and three types of reservoirs are being divided,and classification maps are being accomplished.