Resistivity Simulation And Water Saturation Calculation Of Argillaceous Sandstone Reservoirs

The research object of this paper is argillaceous sandstone reservoir of Neogene Pearl River Formation in Pearl River Mouth Basin.Reservoir and water resistivity are very close,which makes it difficult to evaluate reservoir water saturation.Therefore,it is of great theoretical and practical significance to study the micro-conductivity law and influencing factors of argillaceous sandstone in this paper.This paper mainly carries out five aspects of research on Shale Characteristics Analysis of low resistivity reservoirs,rock electrical parameter regularity analysis,rock conductivity numerical simulation,comparison of simulation results with actual logging data and water saturation model construction,namely:(1)based on rock X-ray diffraction data,analysis of shale content and clay mineral types in shaly sandstone reservoirs;based on whole rock mineral data,casting body The shale content,type and distribution were analyzed by thin section,scanning electron microscopy(SEM),CT scanning and core fluorescence images.(2)Based on the analysis of the micro-distribution characteristics of shale in reservoir,theoretical conductive geometry model and real core conductive geometry model based on typical core casting slice photograph are constructed,and the influence of irregular strip shale on the resistivity of shaly sandstone is simulated by finite element method.(3)Comprehensive analysis of numerical simulation results of rock conductivity and actual logging data,summarize the main factors affecting the resistivity of argillaceous sandstone in Pearl River Mouth Basin and their laws.(4)Based on the shaly characteristics and the simulation results of shaly sandstone resistivity,a water saturation model suitable for shaly sandstone reservoirs is constructed and the water saturation is calculated.The results show that:(1)The argillaceous sandstone reservoir has high argillaceous content and irregular strip distribution of argillaceous sandstone reservoir.(2)Formation factor F decreases with the increase of porosity,while resistivity coefficient I decreases with the increase of water saturation.(3)When the resistivity of argillaceous area is higher than that of pure sandstone area,the current density of argillaceous area is larger than that of pure sandstone area,and the conductivity of argillaceous sandstone is dominated by that of argillaceous area.When the argillaceous content is the same,the resistivity of argillaceous sandstone increases with the increase of the curvature of argillaceous area,while the resistivity of argillaceous sandstone decreases with the increase of Argi.(4)When the resistivity of argillaceous area is less than that of pure sandstone area,the current density of argillaceous area is smaller than that of pure sandstone area,and the conductivity of argillaceous sandstone is dominated by that of sandstone area.When the argillaceous content is the same,the resistivity of argillaceous sandstone increases with the increase of the curvature of argillaceous area,and when the curvature of argillaceous area is the same,the resistivity of argilla.(5)When the water saturation of rocks is more than 80%,the conductivity of argillaceous sandstone is mainly in pure sandstone area,the current density of pure sandstone area is larger than that of argillaceous area,and the resistivity of argillaceous sandstone increases with the increase of argillaceous content.When the water saturation of rocks is equal to 60%,the conductivity of argillaceous sandstone is mainly in argillaceous area,the current density of argillaceous sandstone area is higher than that of pure sandstone area,and the Increase and decrease.(6)Based on the simulation results of resistivity of argillaceous sandstone,the relationship between argillaceous content,rock resistivity and water saturation is established,and the improved water saturation model is obtained.Compared with the water saturation calculated by Indonesia formula,Archie formula and Simandoux formula,the improved water saturation model is more effective.By comparing the numerical simulation results with the actual logging data,the feasibility of the finite element simulation method is verified,and the influence mechanism of shale on the shaly sandstone reservoir is clarified.The high content and irregular strip distribution of shale is one of the main reasons for the low resistivity of the reservoir in the Pearl River Mouth Basin.