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Experimental studies were conducted to enhance the oil recovery by a surfactant-polymer binary combinational flooding system. The surfactant-polymer binary combinational flooding was obtained by mixing the surfactants with the poly(AM-NVP-AS)-1 which was an anti-temperature and salt-resistance tercopolymer and successfully synthesized via free radical polymerization using acrylamide (AM), N-vinyl pyrrolidone (NVP), allyl sulfonate (AS) as raw materials. The initiator was redox system including watersoluble azo compound (AIBAÁ2HCl) and sodium bisulfite (NaHSO 3 ). Petroleum carboxylate dodecyl dibasic carbonylic acid sodium (C12DAS) and carboxyl betaine dodecyl dimethyl betaine (C12DB) were selected in this article. Compared with the surfactant-HPAM, the surfactant-poly(AM-NVP-AS)-1 binary combinational system showed higher apparent viscosity and lower interfacial tension at high temperature and salinity conditions as the result of a better capacity of anti-temperature, salt-resistance, and swept volume. The recovery could enhance over 17% based on the core flooding test under the mineralization of 10,000 mg=L at 65 C.

To alleviate the uneven production of extreme heterogeneous reservoirs, we developed a high-strength natural gas foamed gel system by adding a gel system to the foaming agent solution. The Ostwald ripening rate and the gas molecular diffusion coefficient (D diff) were calculated. The number of bubbles, the average diameter­(D ad), and the poly-dispersion coefficient (U poly) of the foamed gel system have been considered within, as well as the different temperature, salinity, pressure, and crude oil conditions and the stability of the foamed gel system. Moreover, combining laboratory displacement experiments and core nuclear magnetic (NMR) experiments, the oil displacement ability of natural gas foamed gel was studied. The results showed that different from the previous phenomenon of “defoaming with oil”, adding a certain amount of crude oil into the natural gas foamed gel could improve its foaming performance. According to this phenomenon, we conducted experiments on the stability and viscosity enhancement of the emulsion and explored the stability of the pseudo-emulsion film of foamed gel. In addition, this natural gas foamed gel system had a better ability to control profile and enhance oil recovery when the permeability ratio was 75–150. When the permeability ratio was 150, the low-permeability core diversion rate was about 38%, and the EOR was 35.27%. Finally, the core NMR results showed that the main contribution of water flooding recovery came from macropores. In construct, the recovery efficiency of natural gas foamed gel system mainly came from medium and small pores (effective areas not affected by water flooding). This study would provide a different thought for foam in production while dealing with extreme heterogeneity formations.

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