Experimental Study of Depressurization at Polymer Injection Wells by Surfactant

As one of the EOR technologies, polymer flooding is great in economic benefits in the process of industrialized extension of application at oilfields as Daqing, Dagang, Shengli, etc.. However, along with the increase of polymer intake volume, several troubles like high injection pressure, failure of quantum injection, etc. have become increasingly serious, which reduces the polymer flooding effect. The surfactants with ultra-low IFT are able to decrease the oil-water IFT and thus to enhance the water relative permeability, which would reduce injection pressure and increase the intake volume. Here a non-ionic surfactant suitable for polymer injection wells is screened out whose IFT could reach the level of 10^-2 mN/m. Core experiments were done to optimize the injection technologies. It could decrease the polymer flooding pressure by 60% more or less. Field application also shows very good result. This would be meaningful for EOR and energy saving now with high oil price.