Comprehensive Evaluation Method For Low Resistivity Oil Layers In Dongying Sag

For the past few years,thanks to the increasingly investment in exploration,the latent low resistivity oil reservoirs were found gradually,which certifies the great potential of exploration and development.However,due to the diversity of low resistivity reservoir forming factors and the complexity of logging response,the difficulty of logging identification and evaluation has been extremely increased,which is becoming a public issue in the field of well logging interpretation.Dongying sag in Jiyang depression has a large number of low resistivity reservoirs.In view of the difficulty of reservoir evaluation,these reservoirs are tough to be developed.It is necessary to carry out system study and establish comprehensive evaluation method in low resistivity reservoir development,then the guide could be proven for the exploration and development of low resistivity reservoir.This dissertation elaborates the basic features and main types of low resistivity reservoirs in Dongying sag,analyzes the main factors of forming low resistivity oil layers,and defines the distribution characteristics of low resistivity reservoirs,based on the analysis for the low resistivity oil layer of more than 300 wells in 12 oilfields or blocks,such as Jinjia,Binnan,Wangjiagang etc,which are from the data of logging,testing,and core analysis.Furthermore,according to the logging data,it establishes a qualitative identification method for different types of low resistivity reservoirs,and derives Archie formula for the pure sandstone formation,W-S model for the low resistivity reservoir in sandstone,and dual-pore water model for the low resistivity reservoir in high irreducible water saturation,with the result that the accuracy of water saturation calculation is highly improved.More importantly,an effective evaluation technology for the low resistivity reservoir is set up.The results of the study are applied to low resistivity reservoir evaluation of Shi Nan oilfield,which proves the applicability of the method.The low resistance research methodology getting from the analysis of the low resistivity oil layers gives the conclusion of the regional reservoir characteristics and distribution laws,improves the coincidence rate of logging interpretation and achieves the expected goal.It could guide the oilfield development,and provides the reference for the logging interpretation research for the low resistivity oil layers in other oil fields.