The block of Zhuang 115 in the Zhuangxi oil production plant of Shengli oilfield was characteristic of high temperature and middle-low permeability.In order to improve the effect of injection and production,surfactant flooding was proposed.The interfacial tension between betaine surfactant solutions and the crude oil of Zhuang 115,and the adsorption of betaine surfactant on the surface of the qaurts sand,was investigated,as a result,a low interfacial tension displacement system with betaine surfactant as the main agent and sodium humate as the sacrificial agent was developed.The adsorption amount of the system on the surface of quarts sand was 0.4 mg/g,and the interfacial tension between the system and the crude oil was low to 5×10-3 mN/m without the help of alkali.Physical simulation experiments indicated that the oil recovery was enhanced by 17%,based on oil recovery of 53.6% of water flooding,when a slug of 0.3 PV water shutoff agent and 0.3 PV surfactant displacement system were used.This technique had been used in Zhuang 115-5 well in January 2008,and until May 2010,the net output of oil was increased by 1632 tons.