Pore Structure Characteristics And Logging Characterization Methods Of Dong1 Section Of The No.1 And No.2 Structures In Nanpu Sag

According to the core,logging and petrophysical experiments,the lithologic facies and pore structure of the First Member of Dongying Formation in the No.1 and No.2 structural belts in the Nanpu subbasin are classified.Combined with conventional logging,imaging logging and other data,the quantitative identification criteria of lithologic lithofacies and pore structures in the First Member of Dongying Formation are established,and then the lithologic facies and pore structure are classified according to the standard.Finally,analyze how the lithologic facies control the pore structure.The research shows that the reservoir in the First Member of Dongying Formation is relatively good,and it is a typical mesopore permeable reservoir.The main types of pores include intergranular pores,intragranular dissolved pores and intercrystalline micropores;throat types mainly include necked throat,flaky throat,curved throat and bundled throat.Combined with the petrophysical experimental data such as mercury intrusion,core nucleus,rock slices and scanning electron microscopy,the First Member of Dongying Formation of the reservoir is qualitatively divided into four types of pore structure: Class I large hole rough throat type,class II medium hole middle throat type,class III small hole fine throat type and type IV small hole micro throat type.The reservoir quality index RQI is selected to quantify it,and the better the pore structure,the larger the RQI value.Class I reservoirs have the best reservoir performance and seepage capacity,mainly developing water layers and thin oil layers;Type II reservoirs are most common in the First Member of Dongying Formation and mainly develop oil layers,oil and water layers;Class III reservoirs have relatively poor seepage properties,but they may develop low-resistivity reservoirs;Class IV reservoirs are mostly dry layers.At the same time,the lithologic lithofacies of the eastern section of the reservoir have obvious control effects on the pore structure,which is closely related to its strong sedimentary inheritance.It is found that the sandstone facies in the underwater distributary channel mainly develop class I and class II pore structures;The underwater distributary channel fine sandstone facies mainly develops type II pore structure;The fine sandstone facies of mouth bar have typical anti-rhythmic sedimentary characteristics,resulting in the formation of III and IV pore structures in the lower part of mouth bar and the formation of class II pore structures in the upper part of mouth bar.The class III pore structure is developed in the interbedded silt facies between the distributary channels,but the content is low.Defining the control effect of lithologic facies on the pore structure is conducive to further study on the distribution characteristics of the reservoir in the First Member of Dongying Formation and distribution of oil layers.This study can be used to predict reservoir distribution in areas with strong inheritance.