Because plenty of polymers have been added in the surfactant/polymer (S/P) flooding fluid, its viscosity becomes higher. So when S/P flooding fluid flows in the stratum, its threshold pressure gradient is an important influence factor. According to study S/P flooding fluid with different viscosities that flows in different permeability cores, the variation laws of seepage curve have been obtained. The results of the study show that the seepage of S/P flooding exhibits nonlinear seepage in low velocity, and changes gradually to linear flow as the pressure gradient rises. As well, S/P flooding has obvious threshold pressure gradient when its speed is low. The threshold pressure gradient of S/P is related to the permeability of the core and its own viscosity. The higher the viscosity, the lower the permeability of the core, the threshold pressure gradient will be greater.
Using sampling survey data from 20 representative villages, this paper analyzes the status of environmental pollution in mountainous and hilly rural area of Sichuan Province in China, and makes comprehensive analysis of environmental pollution factors of the research area based on BP neural network model. The result shows that there are about 60% of the villages investigated displaying environmental pollution of varying degrees. It also indicates that environment renovation measures conducted by government and labor out-migration are conducive to environmental protection in mountainous and hilly rural area of Sichuan, while the concentration of population and development of rural enterprise have negative impact on local environment. The influence degree of each factor in descending order is labor out-migration, environment renovation measures, concentration of population, rural enterprise development.
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