| The environmental problems caused by petroleum pollutant have been studied by researchers in fields of hydrology and geology, environmental science in home and abroad, and they have become the focuses of research on subsurface environmental pollution control. Petroleum pollutant to subsurface environment is a very complex kinetic progress and because the problems considered are the multi-crossed disciplines and they are very complex, experimental mechanism and pollution prevention were often focused on in studies, and it is seldom to study the dynamic behavior quantitatively of pollutant transport and migration in subsurface environment based on the theories of multiphase flow and solute transport dynamics. Therefore, based on the study results before and using the research results in relative science, Petroleum pollutant transport and migration laws, its temporal and spatial distribution, the constitutive model controlling multiphase flow and the slippage and release coupled model in groundwater environment and so on are deeply discussed. And the coupled dynamic mathematical model of oil-water-gas multiphase flow seepage field and organic pollutant transport and migration concentration field is established theoretically, and the numerical method is given. In addition, the simulation code is developed, and the numerical model is used to predict the temporal and spatial distribution of organic pollutant concentration under the conditions of multi-field coupling effect. It has important theoretical significance and practical value for preventing pollution caused by oil spills more scientificly and effectively. The abstract of this paper includes the following four points:1. By the laboratory column tests, the petroleum pollutant displacement experiment and the physical modeling experiment of waste water with oil in different soils are designed and developed, the petroleum pollutant retention in sandy soil is 45.8%, and it is 76.4% in clays. It provides scientific basis for the quantitative studies of petroleum pollutant transport and migration in subsurface environment. 2. Determination of capillary pressure-saturation-relative permeability relationship curve of oil-water-air flow system is the key technique in studies of petroleum pollutant displacement theories and numerical model in groundwater environment. The parameters' constitutive model controlling multiphase flow is given based on seepage mechanics and parameter inversion optimization theory. And the optimized estimator is obtained by adopting constrained variable metric method to inverse the parameters. It shows that the optimized values by the numerical method in this paper is in good agreement with the experimental data, and the comparison analysis validates the reliability and practicability of numerical model, which solves the sensitivity of the values to the initial conditions.3. On the conditions of considering comprehensively the diffusion, absorption/desorption, distribution between phase surface and the biodegradation progresses, the multiphase and multicomponent model of the petroleum pollutant transport and migration has been established, and the characteristic finite difference method and implicit pressure explicit saturation method are adopted to discrete the coupled model. Moreover, the code (MCTS1.0)is developed to analyze petroleum pollutant transport and migration mechanism in different porous media. The results show after petroleum is leaked out on the earth surface, it will have displacement vertically and horizontally under the pressure of weight and capillary pressure, but the direction of its transport and migration is vertical as a whole. When the pollutant arrives the capillary saturated zone, the vertical movement is blocked by the capillary tension. The pollutant must overcome the oil-water surface inlet air pressure before it entering the capillary zone, and pollutant accumulates on the top of capillary saturated zone to obtain the necessary pressure, and meanwhile it transport and migrate horizontally. In the end...
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