Abstract:

In order to characterize the diagenetic facies and microscopic pore structure characteristics of low/ultra-low permeability sandstone reservoir in Chang 8₁ segments of Huaqing Oilfield, this paper discusses the diagenetic process,cement type of each diagenetic facies, pore evolution, the effect of pore structure on the physical property and fluid seepage characteristics.On the background of reservoir sedimentary characteristics, the test analysis methods are used and the testing oil exploration results for dynamic data validation is made, such as, physical property, casting lamella, scanning electron microscope(SEM), conventional pressure mercury, image pore, X-ray diffraction, oil-water relative permeability. Establishing the reservoir evolution frame in time and space:deposition (sedimentary facies)-diagenesis (diagenetic facies)-pore evolution are the controls of microscopic pore structure of reservoir physical property and seepage characteristics. Different diagenetic facies type have both constructive and destructive dual effects, specificing in the degrees of differences of compaction, cementation, function, dissolution. The qualitative analysis and quantitative description of indoor experiment of diagenetic facies microscopic pore structure have a consistency with testing for oil exploration results and experimental data. It is pointed out that the diagenetic facies and microscopic pore structure characteristics of this kind of reservoir can predict and evaluate favorable space. Chang 8₁ reservoir underwater distributary channel microfacies with chlorite lining edge residual pore-dissolution phase combination of intergranular pore development is the most favorable reservoir belt. Pore of forced compactioncarbonate+illite cementation facies association is damaged too seriously to be an invalid reservoir zone.