WHAT IS Directional Drilling
Directional drilling is 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. Operators use it to retrieve oil and natural gas buried underground, and in situations in which the shape of the reservoir is abnormal. They also use it to adjust pressure created by gas in mines, a process known as degasification.
BREAKING DOWN Directional Drilling
Directional drilling is a technique that the oil and gas industry has used since the 1920s. Because it involves drilling at multiple angles, directional drilling allows oil and gas well operators to approach a potentially productive area without needing to drill a well directly above that area. With directional drilling, one 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. This can be accomplished through the use of hydraulic jets, and allows engineers to adjust the direction the well is drilled in to a certain degree.
Directional drilling is also 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 nineteenth 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 bore the well can be adjusted by a computer using global positioning 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, as well as the best approach for the bore to follow.
Advantages and Disadvantages of Directional Drilling
Directional drilling allows access to areas where a vertical approach would not be possible, such as deposits that are below a body of water, or underneath a community. Because multiple wellheads can be grouped at one central location, directional drilling can also be more efficient, and cause less surface disturbance of the environment. However, directional drilling can make operating wells more difficult, particularly if the well is dug at an inclination of greater than 40 degrees. Sand influx can also be an issue with wells dug through directional drilling.