NaOH, which is used in traditional Alkaline/Surfactant/Polymer Flooding technique, can result in formation damage and equipment corrosion1, 2 . In order to replace NaOH with Na2CO3, a new type Gemini surfactant-DEDS is synthesized. Its dose is very lower than traditional surfactant for ASP combination flooding. Rheological behavior of DEDS/AP-P4/Na2CO3 (ASP) aqueous solution and the effect of salt on it were studied. Conclusions are as follows: DEDS has the same influencent as inorganic electrolyte, and rheological behavior of ASP aqueous solution can be described with power law fluid mode. The apparent viscosity of ASP aqueous solution (AP-P4 2000mg/L, Na2CO3 1%, DEDS 0.423mmol/L and NaCl 1×104mg/L) is 3.88–8.11 that of ASP aqueous solution (AP-P4 2000mg/L, Na2CO3 1%, DEDS 0.423mmol/L), Rheological behavior of ASP solution exhibits a little character of Bingham fluid with the increasing of NaCl concentration. When DEDS concentration is 0.423mmol/L, and AP-P4 concentration is 1500mg/L, ASP ability emulsifing analog oil will enhance with the increasing of Na2CO3 concentration. When Na2CO3 concentration reaches 1%, ASP solution and analog oil is completely emulsified, IFT reaches 10−4mN/m, and ultra-low IFT is realized. Using ASP solution to drive homogeneous test core undergoing waterflooding, recovery efficiency increases about 18%; for nonhomogeneous test core, which permeability contrast is 1.76, its increment of tight permeability is more 6.8% than of high permeability, and ASP solution possesses better profile control property. In comparison with traditional surfactants, DEDS dosage can remarkably decrease, and weak alkaline ASP flooding can be achieved. Extent of formation damage and equipment corrosion of chemicals will obviously reduce, when it is used in field.

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