5.6 Defoamer

In the preparation of slurry, bubbles may be generated, if the slurry has more purples, it may cause serious consequences and cause the slurry density can’t go up.  So it is needed to add defoamer into the cement slurry.
Defoamer can change the bubble surface tension or change the solid phase dispersion ability. With it the bubble generated conditions would not exist.  Usually defoamer has the following characteristics:

1. Can’t soluble in the foaming system.

2. Its surface tension is lower than the foaming system.

Tributyl phosphate and emulsion silicone oil are commonly used defoamer in cementing, generally it only need to add a small amount to inhibit the generation of bubbles. And the dosage is generally for 0.2% (cement weight BWOC).

Table 6-1 is the technical index of kelioil defoamer

Table 6-1 the properties of cement slurry with defoamer