Use of such tubing is only possible because the downhole drilling technology has made it unnecessary to rotate the entire drillstring. The single tube has the advantage of a faster insert and withdrawal times and mechanical simplicity.
#DIRECTIONAL DRILLING TECHNOLOGY SERIES#
This replaces a series of pipes connected by screw threads. Curve radii on the order of 200 to 1,000 meters are common.Ī development that appeared in the 1960s is "coiled tubing" - the drill string is a single tube delivered in a coil as much as 1,500 meters in length. The drill head itself can bore in a preferred direction, cutting more or less during different parts of the cycle. An inline series of packages can move relative to each other to shape a curve in the well bore.
Small vanes may extend or retract at appropriate stages of the rotational cycle so as to bias drilling direction. Steering can be achieved in a number of ways. Inertial navigation technology, developed for aircraft, is often used for position data. This pulse data string can carry commands or diagnostic information.
The same working fluid that powers mechanisms also carries two-way communication between the surface and the drillhead. When passed through a hydraulic turbine, it can drive a drill head.ĭownhole drilling systems work at temperatures as high as 300 F and pressures up to 10,000 psi. The flow of fluid and the difference in pressure between inflow and exhaust is the source of downhole power. Mud is pumped through one or through the annular space between pipes and exhausted through another. The system makes ingenious use of drilling fluid, known as "mud," which is used to lubricate the drill string and to provide hydrostatic pressure to prevent blowouts.ĭrilling involves two or more concentric pipes. This innovation replaces rotation of the entire drill string with independent rotation of the drill head, using a downhole turbine-driven mechanism. ASME has recently recognized it as a Historic Mechanical Engineering Landmark.Ī second key technology, which matured in the 1970s, is the downhole drill motor. The highest patent, which became the foundation of an industrial empire later expanded by Howard Jr., disclosed a drill bit with two rotating, toothed, cutting wheels. It was slow, needed frequent replacement, and required large forces provided by the weight of the drill string. Drilling owes its current efficiency to an invention patented in 1909 by Howard Hughes, Sr.Ī well drill bit once resembled a carpenter's drill. Steering a wellbore is only practical because drilling has become fast enough and economical enough to enable it.
The ability to control the trajectory of a well bore, known under the heading "directional drilling," is a marriage of technologies that matured during the twentieth century. Remarkable as this is, it gets less attention than processes like hydrofracking or the oil shale production which it enables. Well drilling has reached a stage of development where it is possible to drill vertically into the Earth for a mile or more and then make an abrupt turn in any direction. Copyright 2013 American Society of Mechanical Engineers This article contains material published in Mechanical Engineering Magazine Sept. This article was initially written by Robert Woods, ASME Fellow.
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