Study On The Migration Of Contaminants From Alkali-Surfactant-Polymer Flooding In Soil Environment

With the further application of oil EOR, soil ecological environment inevitably be a certain degree of impact as the ASP chemical agents of transportation, preparation, storage, injection procedure. The migration of the chemical agents in the soil is a multi-disciplinary and extremely complex dynamic process, so very few negative impact studies of contaminants in the soil environment at present. At the same time, quantitative study of migration behavior will have important theoretical significance and practical significance to scientific and effective control and management soil pollution problems caused by leakage of oil field.This paper has mainly expounded the migratory mechanism of the soil solute, and detailedly described the basic form and mechanism of contaminants migration, including convection, hydrodynamic dispersion, and adsorption/desorption, degradation, decay and so on, which is based on the numerical simulation. This paper also has explained the conditions and building process of the migration and transformation model, established the mathematical equations and took series of possible extension in comprehensive consideration of soil solute transport mechanism, law of conservation of mass and the convection-dispersion of soluble contaminants in the homogeneous soil/water environment system under the ideal situation.Then, the equations, together with the initial conditions and the associated boundary conditions, make a specific meaningful soil solute transport model. The establishment of the model has provided a reliable theoretical basis for quantitative study the effect the model parameters on contaminants migratory and further study the fate of contaminants in the soil. In this paper, a one-dimensional soil column simulation of LAS migration in 3 months has been used as a validity comparison to the model application in the saturated soil environment. The results show that, for the description of contaminants migration process in saturated soil environment, model has a strong applicability. Contraposing the typical condition that ASP chemical agents have leaked of Daqing oilfield, simulation calculations have been carried out in the precondition of idealizing the complex soil environment. The distribution of contaminants concentration and the prediction of the range of theoretical migration have been figured out by means of calculations and analysis. After ASP chemical agents accidentally leaking within one year, the value of LAS concentration accumulate in a short period of time, then stay in the soil surface regularly. The highest concentration value is 14.5 mg/L. PAM, another sort of contaminants, due to its special physical and chemical properties, the concentration of PAM is about 4.5 mg/L after 10 years though it was regularly distributed. The edge of migration deep into 1.9 m, it follows that the migration process has been slow. As for NaOH, which can penetrate into the aquifer from the soil surface in only three months because of its great water solubility and high reactivity. But the concentration can be negligible, for the impact of water pH is also within the scope of national safety standards. After the independent thorough analysis of the accidental leaked contaminants, a general common migration law of the soluble contaminants in the soil environment can be drawn as a conclusion.