Reservoir Diagenetic Facies Analysis And Logging Evaluation Of Chang 8 In Honghe Oilfield

Honghe oilfield is located Zhenyuan-Jingchuan block which in the southwestern ordos basin,tectonics is mainly distributed in the delta front sand body in the southwest edge of the basin,it is a self-generating and self-storage reservoir,with great potential for exploration.Triassic Yanchang Formation Chang 8 that is one of the main reservoir formation is affected by sedimentation and diagenesis,Chang 8 reservoir has the characteristics of poor physical property,complex pore structure,strong heterogeneity,complex diagenetic minerals and large variation of rock-electro parameters,which bring greater difficulties in oil and gas exploration.Based on Chang 8 low permeability reservoir,the classification and identification methods of diagenetic facies in the study area are established by comprehensive utilization of data such as core,geology and logging data,and on this basis to carry out the research about logging evaluation and "dessert" prediction of the work area.The article systematic analysis the reservoir petrologic feature,studies the diagenesis process,determine reservoir diagenesis stage,and divides the diagenesis into corrosion of unstable components facies,strong corrosion compaction phase,kaolinite cementation facies and carbonate cementation facies in combination with the data of scanning electron microscope and thin sheet.The four properties characteristics,pore structure,seepage and logging response characteristics of different diagenesis facies were analyzed by using mercury injection experiment,phasepermeability experiment and well logging data,and the logging identification of diagenesis was realized through quantitative characterization,Fisher's discriminant analysis and optimization method.Based on this,the reservoir parameter calculation model was established: according to the influence of diagenesis on porosity,the mathematics model of porosity of different diagenetic facies was established;The division of flow units and nuclear magnetic resonance(NMR)logging was used to calculate permeability;To analyze the rock-electric characteristics of different diagenetic facies,and establishes the saturation calculation model based on the change archie formula.According to the mercury injection data,we studied the microscopic pore throat characteristics of the reservoir,and used the cluster analysis to get the pore structure classification.Using the data such as geology,logging and analysis,we studied the main control factors of the reservoir "dessert",and established the classification standard of "dessert" and the pre-exploration method so as to provide guidance and help for the exploration of the favorable reservoirs.