Extended Reach Drilling

Extended Reach Drilling (ERD) describes an extreme form of Directional drilling that achieves horizontal well departures beyond the conventional, or achieves particularly challenging geometries of a well in terms of horizontal versus vertical offsets from the surface location. [ [http://www.redorbit.com/news/business/1064648/indices_describe_complexity_of_drilling_directional_extendedreach_wells/index.html Indices Describe Complexity of Drilling Directional, Extended-Reach Wells] retrieved October 6, 2008 ] The aim of ERD are either to reach a larger area from one surface drilling location, or to keep a well for a longer distance in a reservoir in order to maximise its productivity and drainage capability. The challenges in ERD are in cleaning of the hole and managing of the significant torsion in the drill string as well as any buckling of drill string or casing that is caused by the well geometry and length. It therefore uses special equipment.

What exactly determines a well to be "extended reach" various over time and location with the development of technologies and of experiences. In 1981, a horizontal outstep of 5000 feet from the surface location was considered "extended reach", whilst in recent years over 20,000 feet outstep are achieved. [ [http://www.dog.dnr.state.ak.us/oil/products/publications/healy/pbif/xedd.pdf Alaska Department of Natural Resources] retrieved October 6, 2008 ]

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