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[en] The earthquakes cause appearance of new geological fault and dislocation of rock stratum; the original permeable rock breaks, then the fault can conduct water under the effect of pressure; the stratum with radionuclide is dislocated and connected to the water-conducting fault under the effect of the fault. Under the effect of water the stratum with seepage and the one with radionuclide link up. It causes radioactive pollution on underground water, based on which this paper does a research and makes an analysis of the radioactive pollutant concentration that diffuses along the top and bottom section and centre line of the fault following the seepage. It turns out that in the rock stratum with seepage suffering rupture, the radioactive pollutant effects an elliptical spherical diffusion. In the turning point of the fault, the elliptical sphere makes a turn following the seepage. (author)
[en] Highlights: • A cylindrical oil model was performed inside a silica nanopore. • Molecular dynamics simulation was used to obtain the aggregation of oil phase. • Steered MD simulation was performed to study oil migration inside silica nanopore. • Solvent accessible surface area was used to study the oil migration process. Two suggested systems of oil in the porosity of the reservoir rock after water flooding were built with an oil cylinder inside a silica nanopore. A series of MD simulations were performed to obtain the aggregation structure of oil phase. The results revealed that heavy oil components showed different distribution position inside silica nanopore in the two oil systems. Heavy oil molecules in heptane can precipitate and adsorbed on silica surface. Steered MD simulation was used to study the oil displacement. By analyzing solvent accessible surface area (SASA), we demonstrated the migration of heavy oil components at molecular level.
[en] Highlights: • Translocation mechanism of preformed particle gel in nanopore was investigated. • Effects of surface chemistry and heterogeneity on translocation was scrutinized. • Properties of hydration layer around different nanopores were compared. The translocation behavior of preformed particle gel (PPG) in porous media is crucial for its application in enhanced oil recovery. By means of non-equilibrium molecular dynamics simulation, the translocation mechanism of PPG confined in different silica nanopores were investigated. The influence of surface chemistry and chemical heterogeneity of silica nanopore on the translocation process was revealed. As the degree of surface hydroxylation increases and the heterogeneity decreases, the pulling force needed to drive PPG decreases. We infer that the nanopore’s surface (i.e. surface chemistry and heterogeneity) affects the translocation of PPG indirectly by forming different hydration layers.