| The north-central area of Shanghe oilfield mainly includes some areas of Shang-1 district and Shang-2 district and Shang-3 district.There are many faults in these area.Because of the faults,there are many differences in sedimentary facies types and reservoir properties among the three areas.Moreover,the predecessors have not made a comprehensive analysis of the area.The main horizon of this study is upper Es3,which has been in the stage of high water cut development,and the underground geological conditions are extremely complex.Therefore,it is necessary to carry out the overall study of structure,single sand body and reservoir properties in the study area.Based on the theory of reservoir sedimentology,reservoir characterization and modeling,under the guidance of fine division and contrast of stratigraphic units,this paper studies the sedimentary microfacies of reservoirs,and then studies the structural interface and structural elements.At the same time,quantitative analysis of single sand body in target horizon is carried out,and then reservoir interpretation and reservoir heterogeneity evaluation are carried out.In this study,using the "cycle-thickness" and "contour correlation " comparative method to divide the target horizon,and then divide the Upper member of Es3 in the study area into 5sand formations and 22 sub-layers,and a high-precision stratigraphic framework is established in the north-central part of Shanghe Oilfield.Through detailed analysis of core wells in the area,it is determined that the main sedimentary microfacies in the area are underwater distributary channel,estuary bar and braided channel,and then the planar and sectional maps of the area are drawn.The reservoir structural of three main sedimentary microfacies in the area are determined,among which the 5-level interface is flooded mudstone,the 4-level interface is mainly sandbody draped mudstone,sediment at the bottom of river channel,channel sandbody sedimentary discontinuity,sandbody overlay surface,and the 3-level interface is mainly physical differential sedimentation and diagenetic calcareous sandstone.The quantitative study of the single sand bodies of three main sedimentary microfacies in the area is carried out,which mains to analyze their thickness distribution and determine the correlation between the thickness of single sand bodies and their extension length or width.Based on the analysis of physical parameters,well logs and other data in the area,a logging model of reservoir physical parameters in the north-central part of Shanghe Oilfield is established.Based on the analysis of rock microscopic photographs,scanning electron microscopic photographs and mercury injection data,combined with the results of logging data analysis,the reservoir characteristics in the area are studied from the micro and macro levels,and the main types of reservoir space in the area are summarized,and the pore throat characteristics of the reservoir are determined.In terms of reservoir’s heterogeneity characteristics,this paper mainly studies from three aspects: intra-layer,interlayer and plane,and finally finds that the intra-layer heterogeneity in this area is medium-strong,and interbeds are widely developed,and they are mainly physical interbeds,muddy interbeds and calcareous interbeds.In terms of interlayer heterogeneity,Shang-1 and Shang-3 districts have strong heterogeneity,Shang-2 districts have slightly better heterogeneity,and the overall heterogeneity belongs to the medium-strong level.In plane heterogeneity,influenced by sedimentary environment and different microfacies sand bodies,the horizontal variation of permeability among layers is obvious and the heterogeneity is strong.Finally,the weight analysis method is used to evaluate the reservoir of each small layer in the study area.The results show that the reservoir properties of Shang 1 area is the best,Shang 2 area is the second,and Shang 3 area is the worst. |
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