Efficient oil extraction sewage treatment method

The invention provides an efficient oil extraction sewage treatment method, and relates to the technical field of oilfield produced water treatment. The method comprises the following steps: S1, standing the oil extraction sewage, adding an agent into the oil extraction sewage to settle suspended matters, and taking supernate as first produced water; s2, performing alternating electric field treatment on the first produced water to obtain second produced water; s3, adding a coagulant into the second produced water, and then filtering to obtain third produced water; and S4, treating the third produced water by using a nanofiltration membrane, wherein the obtained filtrate is final produced water. The alternating electric field water treatment process is used in oil extraction sewage treatment, and the problem that oil and suspended solids in produced water exceed the standard is solved. Meanwhile, the application range is widened, the adding amount of a flocculating agent in oil extraction sewage treatment and