Research Progress on the Application of Synergistic Effects of Alkali and Surfactants in Oil-Solid Separation

The use of alkali and surfactant synergistic promotion for oil-solid separation has recently received a lot of attention. In the process of oil-solid separation, the function of surfactants is the key for improving the effect. A common method of oil-solid separation is to rely on the wetting, emulsification and solubilization of surfactants, but in practice the result of single surfactant is not good enough. According to some researches, adding alkali and alkali inorganic-salt to surfactant solution can increasing its activity, reducing interfacial tension between oil and water, increasing ionic strength in solution and promote oil-solid separation with the help of electrostatic repulsion. So delving into the mechanism by which surfactants influence oil - solid separation under alkaline conditions holds pivotal significance for enhancing the efficacy of oil displacement. This article takes chemical flooding as the main research direction and introduces application and mechanism of alkali and surfactant in chemical flooding. Experiments have shown that, The interfacial tension can be as low as 10-4 when the temperature is 53℃, the petroleum sulfonate is 0.4%, and the mass ratio of NaOH to Na2CO3 is 1:2. The mechanism of activation, solubilization and synergy of alkali or alkali inorganic-salt provides a feasible direction for improving oil-solid separation’s effect. It is of great significance for the efficient treatment of oily sludge in oil and gas fields.