Drag-reducing agent for use in injection water at oil recovery

摘要

The present invention relates to the use of a drag-reducing agent in an amount of 50-400 ppm in water having an electrolyte content of 0.01-7% by weight. The drag-reducing agent comprises two zwitterionics, each comprising acyl containing surfactant and an anionic surfactant, where the hydrophilic group is a sulphate, a sulphonate or an ether sulphate. The water containing the drag-reducing agent is suitable to be used in injection water at oil recovery.