摘要：Fracturing is one of the main measures to increase production of oil and gas Wells. Fracturing backflow fluid usually contains oil, formation water, polymer, etc. If it is not treated effectively in time, it is easy to cause greater environmental pollution. Fracturing backflow fluid usually has the characteristics of high salinity and weak alkaline pH value. Different types of fracturing fluids will form fracturing backflow fluids with different properties. Therefore, it is necessary to analyze the characteristics of fracturing backflow fluid to provide references for the ground environmental protection treatment. Aiming at the characteristics of high salinity and weak alkaline pH value of fracturing backflow, two shale wells were chose and carried out experimental study. The oil-water adsorption rate was tested by oil-water adsorption experiment. The composition of rock samples was tested by Energy Dispersive Spectrometer (EDS) analysis. Through Conductivity test (EC), cation exchange capacity test (CEC), ion concentration test, pH value and oxygen concentration test, the main characteristics of fracturing backflow fluid are analyzed in depth. The results show that the dissolution and leaching of minerals in clay is one of the main reasons for the high salinity of the fracturing backflow fluid. And the surface to volume ratio exhibits an important influence on the adsorption process of water and the dissolution and leaching of minerals in clay, and the larger the surface to volume ratio, the higher the ion concentration in the aqueous solution.
