Abstract: Casing sidetracking of production casing string is an important means of bringing back to life abandoned oil wells and enhancing oil recovery. Casing sidetracking has the advantage of cost efficient and time saving, but small annular space clearance increases the friction of cement slurries flowing upward, thus fracturing the formation and resulting in losses of cementing slurry. Another disadvantage of cementing the sidetracking well is the big eccentricity of casing string, which will result in channeling of cement slurry. To solve these problems, a low friction coefficient low density cement slurry was developed. By reducing the density of the cement slurry, the hydrostatic pressure exerted by cement slurry column was reduced. In field operations, cement job quality was remarkably improved. It is proven to be a feasible cementing technology for use in Huabei Oilfield.