Study On The Pore Structure Characteristics Of The Reservoirs Of The Fu 1 Member And The Fu 2 Member Of Funing Formation In The Jinhu Depression, Subei Basin

Jinhu depression is one of the important production areas of Jiangsu oilfield,and the Funing Formation is one of its important outputs.It is particularly important to conduct in-depth analysis and research on it.However,the study of the Funing Formation involves a large and wide range,so this article only carried out some corresponding researches on the pore structure of the reservoir in the first and second members.First of all,this paper comprehensively uses various experimental data to analyze and study Fu 1 member and Fu 2 member of the braided section from the macroscopic perspective(sedimentary and microfacies in the study area)and the microscopic view(rock properties,diagenesis,and physical properties of the study area).On the basis of the theoretical knowledge in the book,the actual situation of the pores in the first member and the second member of the second member was studied in depth to classify and classify the conditions.Secondly,basing on the previous research results,the effects of pore throat type and size,burial depth,diagenesis,sedimentary microfacies,and rock type on the pore structure of the study area were explored.Based on this,the reservoir was evaluated and divided comprehensively.Specific understanding of the following aspects:The types of sandstone in the Fu 1 member and Fu 2 member of the reservoir are mainly fine sandstone and siltstone.The triangle shows that the type of sandstone is mostly type V and type VI,type II is small,and type III is rare.In the diagenesis of the study area,the most destructive effects on the pores are cementation in the early and late stages,followed by compaction.Although the dissolution increases the porosity to some extent and improves the physical properties,the total porosity of the study area After the diagenesis,the overall decline.Combined with the division of the diagenetic stage,the study area begins at the B stage of the early diagenesis,followed by the arrival of the A-stage of the middle diagenesis,which is dominated by secondary pores,and the study area is mostly in the A stage of the diagenesis.Some local burial depths greater than 3200 m are in the B stage of diagenesis.According to analysis of drilling coring and logging data,the study area belongs to the delta depositional environment.The delta frontal subfacies are the main bodies of sand bodies in this area.Taking this as the research object,the types of sedimentary microfacies in the study area can be divided into distributary channels,diversion rooms,distal sheet sands and estuary sand dams.In the process of increasing the depth of burial,the primary pores gradually decrease and the secondary pores gradually increase.The types of pores from the largest to the smallest according to the proportion are intergranular pores,intragranular pores,mold pores,extra large pores,fracture pores,and microporosity.The throat is narrow in this area,the neck is a cast body,the next is a flake or a lamellar throat,and the whole section of the throat can be classified into a small hole-thin throat type;the second member is a middle throat-medium type.The average coordination number is less than 0.7,and the connectivity between gaps is poor.Based on the above analysis,besides the diagenesis and sedimentation effects on the pore structure of the reservoir,it also includes the burial depth,the content of interstitial matter,the migration direction of oil and gas,and the influence of rock type on the pore structure of the reservoir.According to the above control factors,the reservoirs in the study area can be divided into 1,2,3,and 4 levels;they correspond to good reservoirs,better reservoirs,medium reservoirs,and poor reservoirs,respectively.