The Accurate Reservoir Characterization Of Tight Sandstone Reservoir

On the basis of fine stratigraphic division and comparison and sedimentary microfacies study,the macro and micro heterogeneity of the Chang 6 and Chang 8 reservoir groups in the X54 area of Wuqi oilfield are carefully studied by using the data and images of drilling core,welllogging,cast sheet data,mercury intrusion porosimetry and scanning electron microscope.The study shows that the sedimentary facies model of the Chang 6 reservoir and the Chang 8 reservoir in the whole sedimentary period belong to the delta front subfacies,and the microfacies mainly develop three types of underwater diversion channel,river wing and interdistributary bay.The two reservoir's lithology is mainly composed of fine-grained lithic feldspar sandstone,which have experienced five types of diagenesis,such as compaction,pressure dissolution,cementation,dissolution and metasomatism.The diagenetic stage of the chang 6 reservoir is defined as the early B in the middle late-A middle diagenetic stage of the middle diagenetic stage,and the Chang 8 reservoir is in the early stage of the late diagenetic stage.Through the observation of the core cast thin slice and scanning electron microscope,the pore types of the two reservoirs are mainly intergranular pore,feldspar dissolution hole,and cuttings dissolving hole.The throat types include necked throat,flake curved larynx and tube type throat.According to the reservoir characteristics of the study area,the reservoir evaluation parameters are porosity,permeability,oil saturation,sand body thickness,displacement pressure,median radius,lithology and pore type,and the reservoirs studied in the study area are divided into 3 types,and the typical wells of various reservoirs are analyzed and combined with the actual production data.The "Sweet Zone" of tight oil is favorable for evaluation.