Definition - What does Directional Drilling mean?
Directional Drilling, also known as slant drilling, is the process of drilling non-vertical wells. This process of drilling can be broken into three major groups – overburden, surface hole and reservoir penetration – that intersect the vertical well horizontally for extracting coal bed methane. It is considered to be a process of deviating a borehole intentionally along a planned path towards the target that is located at a given direction and lateral distance from surface. This form of drilling is common in shale reservoirs as it helps the drillers to keep the wellbore in contact with the most productive reservoir rocks.
Petropedia explains Directional Drilling
Directional Drilling can be accomplished by the use of, configurations of the bottom hole assembly, instruments for measuring the path of the borehole in the three dimensional space, data links for communicating the measurements, whipstocks, drill bits, mud motors and special components of the bottom hole assembly. The drillers exploit the parameters of drilling like rotary speed and weight on bit for deflecting the drill bit away from the axis of the existing borehole. When the desired borehole direction is achieved, the direction can be maintained by rotating the complete drill string to make sure that the drill bit does not drill in one single direction off from the borehole axis.