| In this paper, the effect of interfacial tension (IFT) magnitude and dynamic on displacement efficiency, have been investigated for Daqing alkaline-surfactant -polymer (ASP) technology, respectively.The investigation indicates that the IFT level mobilizing residual oil related strongly to oil drop length, pore radius, reservoir wettability and pressure gradient. Experiment results demonstrate that the equilibrium and/or dynamic IFT magnitude which mobilizes the residual oil is 10-2mN/m, but 10-3mN/m for Daqing reservoir, especially the contact angle is in the range of 82-90° . Unfortunately, it is the key of the equilibrium IFT magnitude of 10-3mN/m to impede ASP technology be used widely or industrially in Enhanced Oil Recovery (EOR) because those surfactants of which equilibrium IFT between the ASP solution and crude could be lowered to ultra low of 10-3mN/m or more are very difficult to been synthesized or manufactured industrially. In other words, only a few of expensive surfactants could be used as an agent in ASP technology. Usually, not only the decrease of apparent viscosity of ASP solution sharply but also the reservoir destroy are resulted from the addition of higher alkalinities to ASP solutions in order to lower IFT to ultra, as well as polymer expenditure.Based on the results mentioned above, the most favourable lower or non alkalinity ASP systems have been optimized as a hydrophobic association polymer being of favourable viscosifying and viscoelasticity and tolerance of alkalinity, salinity, shearing, and temperature is used as a polymer in ASP solution to instead of HPAM while the synergies between the hydrophobic association polymer and surfactant and alkaline were investigated. Results show that the adsorption Characteristic of the hydrophobic association polymer on some mine sands and Daqing reservoir sandstone is not of that of Langmuir isothermal, but surfactants. The highest adsorption appears at the equilibrium concentration of 400-450mg/L.
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