In the cementing of shallow wells or surface casing, although the cement slurry meets the pumping requirements, there are often problems of long thickening time and slow strength development, which seriously affect the drilling footage and cementing quality. Adding accelerator or early strength agent can change the performance of cement slurry, which can not only meet the requirements of cementing operation, but also make the strength meet the requirements of continuous drilling as soon as possible. Of course, it is sometimes used to alleviate the over retarding caused by the addition of other admixtures, such as dispersant and fluid loss reducer, in order to accelerate the development of compressive strength and shorten the waiting time. Strictly speaking, there are differences between coagulation promotion and early strength: early strength refers to the obvious improvement of early compressive strength, but there is no requirement for setting time. For example, common dispersants have a certain early strength effect; The coagulant requires shortening the setting time, that is, accelerating the setting, regardless of the speed of strength development. These two often have both common properties and differences.

 

Due to the corrosion of chloride ion on downhole steel, the development of chloride free coagulant has been formulated. Since then, there have been non chloride coagulant, chloride free coagulant or chloride free coagulant. In order to adapt to this situation, accelerators are also divided into chloride accelerators and non chloride accelerators.