Microscopic pore throat structure is the key focus and challenge of tight sandstone reservoir research.Regarding the Chang 6 tight sandstone in the Jiyuan area of the Ordos Basin,casting thin sections,scanning electron microscopy,and constant rate mercury injection experiments were used,and fractal theory was introduced to study its pore throat characteristics.The study shows that the pore throat of tight sandstone can be divided into two types:large⁃scale and small⁃scale.The large⁃scale pore throats are mainly dissolution pores,composite pores and curved lamellar throats.The pore throat has large storage space,obvious pore throat deformation,strong heterogeneity and large fractal dimension.The small⁃scale pore throats are strongly compacted and cemented, and mainly consist of intergranular pores,intercrystalline pores and necked throats with little deformation of pore⁃throat space,weak heterogeneity and small fractal dimension.There is a good positive correlation between the fractal dimension and the effective reservoir space.The better the reservoir is,the stronger the heterogeneity will be,and the larger the fractal dimension will be.There is also a good correlation between the fractal dimension and the pore throat structure parameter.The pore throat distribution is uneven,the connectivity is poor,the larger the fractal dimension will be.The mass fraction of clay minerals is an important factor affecting the fractal dimension of pore throat,which in turn reflects the quality and pore throat characteristics of reservoirs.

In order to achieve high ionic conductivity and good alkaline resistance of Polysulfone?based AEMs, chloromethylated polysulfone was prepared by green method, and crown ether?functionalized polysulfone membranes with different triethylamine and amino crown ether contents were then prepared using amino crown ether as cross?linking agent and metal ions and triethylamine as cationic groups followed by crown ether functional polysulfone membrane with triethylamine and triethylamine as cationic groups(PSF?CE _X ?QA_1?X ).The effect of the addition of polyethylene glycol on the membrane properties was explored by introducing the low molecular weight polyethylene glycol (PEG) into the above polysulfone cross?linking membrane.The results shown that the presence of hydrophilic polyethylene glycol helps to facilitate the formation of ordered ion channels in the membrane.The conductivity and alkali?resistant stability of PSF?CE _X ?QA_1?X ?PEG were improved compared to PSF?CE _X ?QA_1?X membrane.Among them, the electrical conductivity of PSF?CE_0.1?QA_0.9?PEG at 80 ℃ is 56.78 mS/cm,which can retain 85% of the original conductivity after alkaline resistance test.In addition,PSF?CE _X ?QA_1?X ?PEG has good dimensional and thermal stability.

This paper in situ introduced a mixture of phytic acid,methanol,water,chromium nitrate nonahydrate,N,N?dimethylformamide in polyvinyl alcohol casting solution, where phytic acid and chromium nitrate nonahydrate formed a metal organic framework (MOF) with a three?dimensional structure. Glutaraldehyde was the crosslinking agent to crosslink polyvinyl alcohol into a network structure, and a series of anion exchange membranes with a porous MOF were constructed for fuel cells（MOF@PVA）. During the experiment, the structure and properties of the membranes were optimized by adjusting the Cr³⁺ content. Characterization and performance test results show that the obtained composite membranes are flat and uniform in morphology, with a large number of pore structures available for OH^- migration and retention of water molecules. Additionally, membrane conductivity, water content, and mechanical properties increase with the rising Cr³⁺ mass fractions. When m(Cr³⁺)/m(conductive film) is 0.012, the conductivity is the highest, that is 24.9 mS/cm. The membrane conductivity is only reduced by 8% after being immersed in a 3 mol/L NaOH solution at 80 ℃ for 168 hours.