Directional drilling within the fields of petroleum engineering is considered as a technique that contemplates the drilling of any oil well that does not follow a vertical trajectory.
However if we analyze this concept a little, we can make some considerations, because if for example we are going to drill a well vertically we also need the knowledge of directional drilling, because in order to maintain the verticality of a well, we can not get out of its vertical trajectory, this vertical trajectory will only accept some degrees of inclination offset to be considered vertical, In case it exceeds the allowed degrees of inclination, then it is corrected to maintain the verticality, this correction is only possible if you have knowledge of directional drilling, especially knowledge that gives us the geometry in relation to angles of inclination, trigonometric relationships, among others.
The other important consideration to highlight is that the directional drilling technique is a technique that has evolved and is increasingly perfected thanks to its origins in the drilling of oil wells and with the academic help provided by petroleum engineering, however the directional drilling technique is a technique for drilling wells that can easily be extended to drill water wells, wells to extract methane from coal mines, among others.
There are many historical reasons that give rise to directional drilling, although it is true that in the beginning the oil industry did not give much importance to drill oil wells with a different directionality to one that was not vertical, then some events occurred such as: having to deviate from a populated area and for that had to drill horizontally. Also the operational problems that occurred while drilling were due to drilling in some geological strata that were structural faults where there were abnormal pressures, once it was understood the importance of being able to drill directionally, it was possible to use this technique to deviate from such structural faults and optimize the drilling of wells without presenting as many operational failures as those presented before the implementation of this technique.
Logically there must be a complement of knowledge between the directional drilling technique and geology, the geological element that helps us is the contour map and that through geological knowledge can identify the lines of structural faults, so that finally with the directional drilling technique we can deviate the vertical trajectory of the well to a trajectory that completely avoids the structural faults, which can accumulate abnormal pressures that under normal operating conditions in the drilling of a well can cause a blowout of fluids such as oil and gas and cause an explosion at the surface.
Below is a clear example of what a structural map representation would look like in which a structural fault above the oil reservoir can be identified:
There are many benefits that this technique has brought to the oil industry, however it also has its disadvantages, among which stands out the fact that through the implementation of horizontal drilling oil can be stolen from one country to another, however that is something that has had to live with during these years of long oil exploitation.
From the academic point of view this technique has provided a great field of knowledge, where it is necessary to advance in technology on tools such as downhole engines that help to optimize the implementation of directional drilling.
As a conclusion I can tell you that directional drilling is a technique that will prevail for as long as it is necessary to drill wells that not only have to be oil and natural gas wells, but it is a technique that will continue to be applied even for drilling water wells, among other types of wells.
Reference consulted and recommended