Study On Logging Evaluation Of Low Porosity And Low Permeability Reservoir Of Funing Formation In S19 Area Of Gaoyou Depression

Block S19 sandstone reservoir of Funing Formation in S area of Gaoyou Sag in Subei Basin is controlled by sedimentary environment.Sand bodies are vertically superimposed.The physical properties of target strata are poor.Its pore structure is complex and affected by shale and lime content.It is more difficult to build a model of reservoir physical property.It has obvious Non-Archie phenomena in the relationship between saturation and resistivity.Generally,the reservoir parameters cannot be calculated accurately and it is difficult to identify pore fluid.It's necessary and important to improve the accuracy of reservoir parameters calculation and identification of fluid properties of Funing Formation in Block S19.Logging evaluation technology of low porosity and low permeability reservoir based on experimental physics and experimental analysis is carried out combined with geological characteristics and production testing in this paper.The logging curves are standardized to eliminate the errors caused by different logging tools in different logging series.The corresponding standardized data tables are established according to the histogram and the trend surface in the study area.Based the core data,logging description and logging data,the relations of the lithological,physical,electrical and oil-bearing characteristics in the study area are systematically analyzed.The oil-bearing state method and the loss rate method are jointly analyzed to obtain the lower limit data of reservoir physical properties in the study area.The flow unit index is regarded as the index parameter of reservoir classification,which is calculated with the Fisher algorithm and the probability and statistics method.Comparably,the probability and statistics method is more accurate.On the basis of volume model,the porosity,permeability,lime content and rock electrical parameters are optimized by using index classification indicators of flow units.The accuracy of reservoir parameter model is greatly improved.Combined with the oil testing data and single well production information,the fluid interpretation chart is established with the acoustic time difference,natural gamma ray and deep induction resistivity,porosity,saturation and resistivity.The interpretation coincidence rate reaches 87.5%,which satisfies the actual production needs.