The invention discloses a
silyl ether composite defoaming agent as well as a preparation method and an application thereof, and belongs to the technical field of oilfield
chemical industry. The composite defoaming agent is prepared from components in percentage by
mass as follows: 15%-25% of polysiloxane, 15%-25% of polyether, 2%-5% of hydrophobic white
carbon black, 2%-5% of a compound emulsifier, 1%-2% of a stabilizer and the balance of water. The preparation method comprises steps as follows:
polydimethylsiloxane and polyether are added to a reaction kettle, the temperature is increased to170-200 DEG C, and the materials are continuously stirred for 1-2 h; hydrophobic white
carbon black is added and stirred to be homogenized; the compound emulsifier, the stabilizer and water are added,the temperature is reduced to 60-80 DEG C, a stirring reaction is performed at constant temperature, and the
silyl ether composite defoaming agent is obtained. The composite defoaming agent is used for defoaming and foam inhibition in a stirring process of
well cementing slurry containing an admixture. The composite defoaming agent is high in defoaming and foam inhibition capacity, can be appliedto various
cement slurry systems, and is good in compatibility with common admixtures, safe and
environmentally friendly.