Study On Environmental Behaviors Of Wastewater From Well Fracturing And Trial Oil Production In Oilfields

Recently, with the fast exploitation of oilfields in our country, plenty of soil and water were seriously polluted, especially in some local area. Soil is very important and basic condition for peoples'living and development. If the pollution of soil is beyond its self-purified capability, soil actions will decrease, even die away. Overpollution to soils will do harmful to biology and human live, even affect the social economy and the ecosystem. So it is important and necessary to study the migration and transformation of contaminants in the soil for protection of soil environment during the exploitation of oilfield. A well fracturing process is one step of increasing output and injection in oil production. The trial oil production is an important operation before the beginning of mass oil production.In this paper, wastewaters from the well fracturing process and trial oil production were analyzed. By the experimental results, the kinds and amounts of pollutants were determined and their environmental impacts were evaluated, the law of migration and transformation of contaminants in the soil were studied by the soil column experiments in laboratory. Based on designing the mathematical model, the migration and transformation of pollutants in soil were simulated. Considering the environmental condition, including climate, moisture and the characteristic of soils in oilfields, the boundary condition was obtained for simulation of the migration status of the contaminants such as oil pollutants and acidity pollutants ( H+,Cl-,F-). The simulated results show that the relation between the concentration of pollutants and the depth of soil can be expressed by a negative exponential equation, which is consistent with the experimental ones. So the mathematical model is well fit to the practical processes and behaviors in soil.This study can predict the environmental behaviors of oil pollutants including oil leaking in production, storage and processing.The local characteristics of environmental behavior of pollutants can provide a scientific basis for the environmental impact assessment and protection.