![]() In 1934, John Eastman of California became a pioneer in directional drilling. Counter-experience had also given early directional drillers ("DD's") principles of BHA design and drilling practice which would help bring a crooked hole nearer the vertical. Prior experience with rotary drilling had established several principles for the configuration of drilling equipment down hole ("Bottom Hole Assembly" or "BHA") that would be prone to "drilling crooked hole" (initial accidental deviations from the vertical would be increased). Many of the earliest innovations such as photographic single shot technology and crow's feet baffle plates for landing survey tools were developed by Robert Richardson, an independent directional driller who first drilled in the 1940s and was still working in 2008. A series of consecutive surveys are needed to track the progress and location of a wellbore. These 3 components combined are referred to as a "survey". Three components are measured at any given point in a wellbore in order to determine its position: the depth of the point (measured depth), the inclination at the point, and the magnetic azimuth at the point. ![]() Sperry did this under contract to Sun Oil (who were involved in a lawsuit as described above), and a spin-off company " Sperry Sun" was formed, which brand continues to this day, absorbed into Halliburton. The next advance was in the modification of small gyroscopic compasses by the Sperry Corporation, who were making similar compasses for aeronautical navigation. In certain circumstances, magnetic fields could be used, but could be influenced by metalwork used inside wellbores, as well as the metalwork used in drilling equipment. Measuring the azimuth (direction with respect to the geographic grid in which the wellbore is running from the vertical), however, was more difficult. Measuring the inclination of a wellbore (its deviation from the vertical) is comparatively simple, requiring only a pendulum. Initially, proxy evidence such as production changes in pre-existing wells was accepted, but such cases fueled the development of small diameter tools capable of surveying wells during drilling. This realization was quite slow, and did not really grasp the attention of the oil industry until the late 1920s when there were several lawsuits alleging that wells drilled from a rig on one property had crossed the boundary and were penetrating a reservoir on an adjacent property. Probably the first requirement was the realization that oil wells - or water wells, are not necessarily vertical. Many prerequisites enabled this suite of technologies to become productive. The production ratio for horizontal wells versus vertical wells is 3.2 to 1, while the cost ratio of horizontal versus vertical wells is only 2 to 1. The United States Department of Energy indicates that using horizontal drilling can lead to an increase in reserves in place by 2% of the original oil in place. It not only increases reservoir recovery factor, but also minimizes drilling and operational footprint by reaching the whole reservoir from concentrated spots. This article is mainly focused on oilfield directional drilling.ĭirectional drilling is a very valuable tool in oil/gas exploration and production. or Horizontal Directional Drilling) Directional boring, and in-seam directional drilling (Coal-Bed methane). ![]() It can be broken down into three main groups: Oilfield Directional Drilling, Utility Installation Directional Drilling (or H.D.D. Directional drilling (or slant drilling) is the practice of drilling non-vertical wells by deviating a wellbore along a planned path to a target located a given lateral distance and direction from vertical.
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