A. K. Danilov, E. M. Levkovich, R.S. Privalihin
The article briefly describes the types, methods and technologies of horizontal directional drilling for different rocks belonging to V–VII strength category, as well as drilling equipment and tools. The effect is also analyzed of the factors on drilling bit drift in the zone of coal-rock interface under Plat lateral force applied to the bit and on drill rod deformation in the borehole between the applied lateral force and the rod contact with the borehole face during rod bending. Engineering proposals on the stabilizing of drilling of rocks varying in strength in unfavourable conditions, and design approaches aimed at the enhancement of stiffness of a drilling tool leading component would have a significant effect on drilling direction.