The Gemini Anionic Surfactant Synthesis And Flooding Experiment

With the increase in world energy demand, the requirement on oil exploitation volume and recovery efficiency has become higher and higher. Conventional oil-recovery methods only have a 1/3 recovery of crude oil, namely, about 2/3 of crude oil remains in the reservoir. When the crude oil production of conventional methods declines, improving recovery efficiency will play an important role in the field of resource preferably utilized. The tertiary recovery, introduced of physical-chemical and biological techniques to reinforce the exploitation of reserved oil, can raise the recovery to 30%.In the tertiary recovery, surfactant flooding is of great potential in enhanced oil recovery. Previous studies show that the mechanisms of surfactant oil-displacement include:(1) low interfacial tension mechanism; (2) wettable reversal mechanism; (3) emulsification mechanism; (4) increasing charge density mechanism; (5) coalescence and oil band formation mechanism.Gemini surfactant, a new type of surfactant with a special constructure, is composed of two or more amphiphilic groups covalently bonded by a spacer group. Just like traditional surfactants linked by spacer group, Gemini surfactant possesses higher surface activity than the traditional do.This paper mainly introduces a new type of surfactant:Gemini surfactant. Gemini surfactant is of the kind made up of two hydrophilic groups and two lipophilic groups covalently bonded by spacer group. In this article, ethylenediamine, methyl acrylate, n-butyl acrylate and aliphatic acids (capric acid, lauric acid, myristic acid, palmitic acid) were direct materials to synthesize anionic Gemini surfactants. The surfactants were characterized by elemental analysis and IR spectre. Also, the surface tension, interfacial tension, critical micelle concentration (CMC) and contact angle of their solution were tested. Various types of surfactants were recomposed according to the surfactant formulating principle, and the superiorly performed mixture systems were selected. With the authentic sandstone micro-model, the synthetic Gemini surfactants were tested through the laboratory simulation of oil displacement experiment. Compared the properties of the products, the most suitable surfactant for tertiary recovery was ultimately obtained. The materials for synthesis are cheap and easy to get, meanwhile Gemini surfactant owns high surface activity, low Krafft point and preferable water-solubility. As a result, Gemini surfactant is expected to replace the alkaline of ASP flooding, reduce the dosage of polymer in ternary system, or even replace the polymer. Surfactants reasonably formulated, new avenues to the tertiary oil recovery will be widely opened up.