Application Study of Composite Surfactant in Well Flushing of Yingdong Oilfield

Abstract Yingdong Oilfield’s structure upper plate is located on the southern edge of the Qaidam Basin’s Hero Ridge thrust uplift zone, with an altitude ranging from 2900 to 3500 meters above sea level. The reservoir’s formation pressure is 8.08 MPa, and the reservoir’s pressure maintenance level is relatively low, leading to the continuous increase in the number of low pump efficiency wells, which in turn exacerbates wax deposition and well plugging, increasing the difficulty of maintenance day by day. In order to solve the problem of wax formation in Yingdong oilfield, the research of composite surfactant well flushing was carried out.. Laboratory experimental results indicate that composite surfactant can effectively reduce the surface tension of injection water and the oil-water interfacial tension; they can significantly alter wettability; and the anti-wax rate is as high as 33.03%, the wax cleaning rate is as high as 51.31%. The experimental results show that the application of composite surfactant on well flushing in Yingdong oilfield has better effect. Field trials show that Yingdong Oilfield accumulated 2,290 wells washed in 2024, the average concentration of composite surfactant used is 0.3%, the effective well return cycle is shortened by an average of 1.3 days, the effective well flushing cycle was extended by an average of 10.5 days, the effective well load difference decreased by an average of 3.79 KN, the effective well current decreased by an average of 4.64 A, and 3,106 tons of oil increase was realized by upgrading the time of production of the wells. Composite surfactant well flushing in Yingdong Oilfield showed better results overall. The application of composite surfactant in well flushing of Yingdong Oilfield has effectively boosted the maintenance of wells in Yingdong Oilfield, promoted the increase of production and efficiency of the oilfield, and provided strong technical support for the sustainable development of the oilfield.