| The system researches on improving oil recovery with foam were firstly carried out in the high-temperature and high-brine reservoirs of Zhongyuan Oilfield on the bases of the theories and the late outcomes of foam flooding.The property of foam fluid was generalized and analyzed systemically such as the parameters of foam quality, foam heat physical property, the causticity of foam, the biological degradation of foamer, the toxicity of foamer and so on. The main factors affecting the stability of foam were generalized, which include the system constitutes, the foam properties, the distribution of the bubble size, the absorption membrane, black film, and other environmental factors. Basing on the theory and practical application, this paper contains the integrated theory and practice system of foam and foam flooding technology.Based on the theory of surfactant, the foamer of new-style anion surfactant PAS-12 was synthesized with steady performance, cheaper and other good characteristics such as high foaming ratio, good stability, good rheology, anti-calcium, anti-salt, resistance to high temperature and so on. Basing on the theory of macromolecule chemistry, the new polymer PS-3 with anti-salt is synthesized as foam-stabilizer. Despite the strict condition of synthesizing and high price it has steady performance, good viscosities, good compatibility with other polymers and good resistance to temperature up to 80 °C and brine up to 71500mg/L.The optimal establishment of foam system in the static condition was as follows: 0.2% PAS-12, 1500mg/L PS-3, 1% co-active (alkali) in the formation water of 71500mg/L salinity in Zhongyuan Field. This foam system in 80°C has the foam of 490ml. There were three types of structure of the foam with SEM: overlapping ring structure, composite structure of two phases and group structure. According to the experiments and the analysis of foam absorption film' s micro-configuration and rheology, the foam has two characteristics of viscoplastisc and salt effectiveness. The researches on abilities by static absorption and dynamic absorption were as that: PAS-12 > alkali (NaOH) > PS-3.We found out that the configuration of foams changed from rough to fine with the increase of gas-liquid ratio and PV injection during the process of researching on the foam' s mobility in porous medium. But when the gas-liquid ratio was too large, the configuration of bubbles changed from gas isolated by liquid to liquid isolated by gas and was easy to crack. The bubbles moved ahead in the process of burst and regeneration. The liquid flowed through network of bubble-liquid films and the porous medium. Macroscopically the foams moved ahead in a group, continually bursting and regenerating. During the process of mobility the foams could keep quite a long slug of stability.Results of different injections indicted that the alternate injection was the optimal way; Two parallel cores with different permeability 1.91 V- m"' and 0. 34 u m2 were flooded by water. The ratio of enhancing oil recovery of the foam system was 27. 6% and 17. 9% respectively. This proved that the system had good abilities to improve oil recovery and microvisual displacement efficiency.
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