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Extended Reach Drilling (ERD) is directional drilling of very long horizontal wells. The aims of ERD are: a) to reach a larger area from one surface drilling location, and b) to keep a well in a reservoir for a longer distance in order to maximize its productivity and drainage capability. Today’s challenges in ERD are hole cleaning, managing the mechanical loads on the drill string and managing downhole pressure. There is also the cost issue〔Kaiser, Mark J (2007-09-13) (Indices Describe Complexity of Drilling Directional, Extended-Reach Wells ) ''Red Orbit'', retrieved October 6, 2008〕 to consider. ==Definition== Early ERD-well definitions related wells to those that exceeded some step-out/vertical-depth ratio (often 2:1). However, for most highly deviated wells in deepwater environments, this definition clearly does not fit. Some methods have evolved to categorize wells according to their stepout within different vertical-depth ranges. ERD wells then can be described conveniently as shallow, intermediate, deep, and ultradeep. Other variants are associated with operating in deep water and high-pressure/high-temperature environments. Currently, there is no generally accepted ERD-well definition. What exactly determines a well to be "extended reach" varies over time and location with the development of technologies and of experiences.〔Negrao, Alvaro (May 2009) (Multilateral or Extended Reach ) ''SPE Website'', retrieved October 6, 2008, link updated May 1, 2013〕 * On 28 January 2011 the world’s longest borehole was drilled at the Odoptu field, Sakhalin-I with a measured total depth of 12,345 m (40,502 ft) and a horizontal displacement of 11,475 m (37,648 ft). * Maersk Oil Qatar had the previous world record in a well with a measured depth of 12,290 m (40,320 ft) including a horizontal reach of 10,900 m (35,770 ft) in the Al Shaheen Field offshore Qatar.〔Sonowal, Kumud et al. (2009-11-03) (Continuous improvements lead to Maersk Oil Qatar’s longest horizontal well in the world ) ''Drilling Contractor'', retrieved September 9, 2011〕 * On Aug 26th 2013 the Orlan Platform drilled the world longest ERD offshore with a MD of 12300m. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Extended reach drilling」の詳細全文を読む スポンサード リンク
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