Dielectric Dispersion Experiment Of Rocks And Dielectric Saturation Model Simulation

With the rapid development of world economy,the demands for energy grow with each passing day,this puts higher requirements for oil and gas exploration and exploitation.Thus the low porosity and low permeability reservoir has being the important exploration object,which attracts great attention at home and abroad.In addition,after years of exploration and development of oil fields,oil and gas reservoir water content keeps increasing,and this causes low resistivity oil reservoir and high resistivity water layer which brought great distress distinguishing oil and water layers.The dielectric logging which measures significant differences dielectric properties of oil and water layers can be more convenient,and influence of salinity is small foe this method.Schlumberger launched a new generation dielectric scanning logging instrument,the measurement precision of this instrument is greatly improved,can be a more accurate assessment of computational physics information of rock.While domestic related research and development has not kept pace with the progress of foreign instruments.This paper mainly studies dielectric constant and frequency dispersion characteristics and model of low porosity sandstone,which conforms with current situation of oil exploration and development,we did basic research work for the development of data processing and interpretation of domestic dielectric logging instrument.The Agilent E4991 A impedance analyzer and 16453 A fixture are used in this experimental measurement.Including 8 pieces of sandstone samples from middle to low porosity,the measuring frequency is from 1MHz to 1GHz,saturated with distilled water,the mass fraction of 0.5% and 5%NaCl solution saturation in the process of dielectric constant measurement.Capacitance experiments were carried out using TH2829 C digital bridge to measure rock capacitance of 1kHz,10 kHz,100kHz,500 kHz saturated by 0.5%NaCl solution.The influence of measuring frequency,rock porosity,saturation and shale content are discussed respectively,together with bound water and free water dielectric difference.Then we simulated two dielectric models with measurement data,especially focused on the analysis of 20 MHz,100MHz,300 MHz data corresponding Schlumberger dielectric scanner.Through the study of the relationship between clay double electric layer,Maxwell-Garnett interface polarization and dielectric constant of rocks,we can determine different distribution of water in rock porosity by low frequency rock capacitance experiments,which relates to rock irreducible water saturation.Through the study of measurement frequency,porosity,saturation,clay content on dielectric permittivity of rock,we believe that it's needed to consider various factors in the selection of electric saturation model,we should select the appropriate simulation model.This article provides petrophysical data foundation for domestic equipment research and development,data processing.