DEFINITION of 'Directional Drilling'
A drilling technique in which a well is bored at multiple angles. Directional drilling most often refers to drilling at non-vertical angles, including horizontally. It is used both to retrieve oil and natural gas buried underground, and is useful in situations in which the shape of the reservoir is abnormal. It is also used to adjust pressure created by gas in mines (degasification).
BREAKING DOWN 'Directional Drilling'
As a technique, directional drilling allows oil and gas well operators to approach a potentially productive area without the need for a well to be drilled directly above that area. A central site can service multiple well bores that reach multiple locations at non-vertical angles. This reduces the number of well facilities that must be built and maintained. Not needing to build new wells may also lead to the exploration of smaller reservoirs that would otherwise be uneconomical.
Early directional drilling involved pointing the drill bit at an angle other than vertical, resulting in a straight line away from the well. Modern drilling techniques allow the use of drill bits that can bend; allowing engineers to adjust the direction the well is drilled in to a certain degree. This can be accomplished through the use of hydraulic jets
Directional drilling is used in the development of mines in order to reduce the risk of potentially dangerous gas ruptures. In-mine drilling techniques allow companies to create bore holes far in advance of the mine face.
While the fundamental concepts of directional drilling date back to the 19th century, it has become a more popular technique as computer-aided technology has become more common. The angle of the drill bit being used to bored the well can be adjusted by a computer using GPS signals to pinpoint the location of an oil and gas field. Engineers create 3-D models of the field to determine the best location for the well, and the best approach for the bore to follow.