Oil and gas horizontal well drilling is associated with big amount of challenges that may occur while drilling or completion operations. The main risk in horizontal well cementing is sedimentation of cement slurry. Unlike vertical wells where the integrity of the well is generally not reduced, even a minor water loss leads to the formation of the channel created by the mixing fluid under the upper wall of the horizontal borehole, where contact of the cement stone and rock may lack, leading to annular space flows. Obviously, the main way to improve the quality of cementing is modification of the properties of cement slurry by adjusting its composition. Introduction of various additives to a certain extent alter the basic characteristics of the cement slurry, and some of them vary considerably, improving one property results in the inevitable deterioration of others. High sedimentation stability and pumpability of cement slurry are just some of these properties. While cementing sidetracks high pumpability of cement slurry is a basic requirement for its composition. In the condition of small annulus, bottomhole pressure when pumping the slurry can reach values exceeding leak off and fracturing pressure that affects the success of the operation and subsequent well productivity. Also, considering the small size of the cement stone it must have high strength characteristics. The paper includes analysis of applying cement slurries and additives for horizontal wells. The current avenues of scientific research are chosen.