When surfactants are adsorbed on the mutually exclusive interface between oil and water, the surface tension between them can be reduced due to the action of hydrophobic and hydrophilic groups. Closely related to this are wetting, dispersion, foaming and defoaming.

 

(1) Wetting: wetting is the phenomenon that one fluid on the solid surface is replaced by another fluid. For example, on the surface of glass or metal, water is used to replace air, and liquid displaces gas from the solid surface. This phenomenon is called wetting or wetting. Generally, the effect of wetting objects with the help of surfactants is called wetting or wetting.

 

(2) Dispersion: people usually call a system composed of solid uniformly distributed in liquid in the state of small particles as dispersion system, liquid as dispersion medium or continuous phase, and solid as dispersed phase or discontinuous phase. Usually, after cement particles are mixed with water, some cement particles are agglomerated due to heterogeneous electrostatic agglomeration. If a small amount of surfactant is added to the solution, the surface tension of the dispersed phase can be significantly reduced. At the same time, because the ionic surfactants are adsorbed by particles with the same charge and repel each other, they can not be close to each other, it is difficult to form a condensed structure, and have a dispersion effect.

 

(3) Foaming and defoaming: in the cement slurry system, for general cement injection operation, it is desirable to add non foaming additives so as not to affect the water filling efficiency during pumping. However, in compressible cement and foam cement, air entraining agent, air entraining agent and foam stabilizer are used not only to prevent gas channeling, but also to reduce the density of cement slurry. Foaming needs to increase the surface tension, while defoaming is to reduce the surface tension.