Experimental study on the core permeability damage rate resulted from the injected water of the Jiudong Oilfield

In the Jiudong Oilfield, the immediate vicinity of water injection well tends to suffer blockage, which seriously impact the recovery factor of the oilfield. In order to investigate the reasons for the formation of the blockage in the water injection wells of the Jiudong Oilfield, the main water quality indexes of the injected water were tested and analyzed, and the core permeability damage degree resulted from the water quality indexes of injected water was quantitatively analyzed by conducting core displacement tests. Firstly, the core permeability damage rates resulted from the salinity, content of suspended matter, particle size of suspended matter and oil content of injected water were tested by means of the single-factor analysis method. Then, the orthogonal experiment was designed based on the single-factor test results. In the orthogonal experiment, the core permeability damage rate caused by the synergetic effect of salinity, content of suspended matter, particle size of suspended matter and oil content was analyzed. In addition, the cores experiencing the orthogonal experiment were analyzed under scanning electron microscope to further clarify the damage of injected water to the cores. The orthogonal experimental results show that the core permeability damage degree resulted from the content of suspended matter is the highest, which is followed by the particle size of suspended matter and the salinity, and that from the oil content is the lowest. And the core permeability damage rate is the minimum when the salinity of the simulated injected water is 90%, the content of suspended matter is 8 mg/L, the particle size of suspended matter is 2 μm and the oil content is 6 mg/L.