Abstract
In low permeable reservoirs of Daqing oilfield, the water drive recovery efficiency is low and other technology, such as polymer flooding, which have been successfully put into use for largely enhance oil recovery in medium or high permeable reservoirs could not be applied in the low ones due to high injection pressure.
Based on the description of characteristics and surfactant flooding mechanism, the practical conditions of Daqing oilfield low permeable reservoirs were simulated. Some experimental EOR studies of new surfactant named SY used for flooding have been done in the lab with low permeable artificial and natural cores. In a constant temperature, after the water flooding, 5 different concentrations (0.1%, 0.2%, 0.3%, 0.4% and 0.5%) of SY surfactant were used for flooding.
The result shows that the displacement efficiency of the SY surfactant is different under 5 concentrations, at the concentration of 0.5%, the recovery efficiency could be enhanced greatly, by 12.2%, and at the concentration of 0.3% and 0.4%, the recovery could be enhanced by 11.78% and 11.86%, nearly that of the concentration of 0.5%, but at the concentration of 0.1% and 0.2%, the recovery could only be enhanced by 5.23% and 6.85%.Because of the low surfactant usage and good oil recovery enhancing characteristics, 0.3% is the best concentration to be used. Reservoir simulation predicts that if the concentration of 0.3% can be used in low permeable reservoir C-1 block in Daqing oilfield, the recovery can be enhanced by 3.5% in 3 years flooding, and the final recovery can be enhanced by 11.52%.
The study has reference value to low permeable oilfield which will use the new type of SY surfactant to enhance recovery.
