Latex refers to the emulsion polymer, which generally is very fine ball suspension emulsion polymer particle, and the particle size is between 200-500 nm. Adding the latex into the cement, can increase the toughness of the set cement, restrain the cement hydration contraction, reduce the fatigue, improve the slurry and sidewall interface structure and realize the aim of anti-fluid channeling. In addition to its anti-fluid channeling function outside, it also can increase cement stone flexural strength, reduce the broken degree of perforation to cement ring. Latex can clog cement internal pore, fast become the membrane in the process of fluid loss. It plays a role of filter, especially for the horizontal lateral wells and slope, and other special conditions cementing.
In the 1950 s the United States Dowell company first used latex in the cementing project, improve the cementing quality efficiently. The latex provided including polyvinyl dichloride and the vinyl acetate. Then the Halliburton and BASF used carboxylated styrenebutadiene lattices to the cementing project.
Due to the complicated cement slurry ingredients, the high ions concentration, and the complex underground environment, the mechanical stability and the chemical stability of the latex are demanded. The de-emulsifying and flocculation phenomenon will lead to serious cementing accident in the process of pumping. So in order to improving rubber latex stability, both at home and abroad do a lot of experimental studies. The most is the carboxylic butyl benzene latex, along with the appropriate latex stabilizer, such as surfactant, naphthalene acid polycondensation etc.
Table 9-1 is kelioil CT610 series latex’s performances index.
The application temperature is 30～150℃（BHCT）and the dosage is 5.0～20%（BWOC）.
Due to the excellent properties of set cement with latex, the high grade rate and up-to-standard rate is high. But because the cement latex exist demulsificationbroken phenomenon, and there is no good solution methods, so the risk is bigger when use cement latex additive in cementing project.