# Extended reach drilling > Mediated Wiki article. Canonical URL: https://mediated.wiki/source/Extended_reach_drilling > Markdown URL: https://mediated.wiki/source/Extended_reach_drilling.md > Source: https://en.wikipedia.org/wiki/Extended_reach_drilling > Source revision: 1325846387 > License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) Technique used to drill long horizontal wells **Extended Reach Drilling** (**ERD**) is [directional drilling](/source/Directional_drilling) of very long non-vertical 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. Challenges in ERD are hole cleaning, managing the mechanical loads on the [drill string](/source/Drill_string) and [downhole pressure](/source/Downhole_oil%E2%80%93water_separation_technology), and cost.[1] ## 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.[2] - On 24 April 2015 the world's longest borehole was drilled and completed from the Orlan Platform in the Chayvo Field, Sakhalin-1 Project with a total measured depth of 13,500 m (44,294 ft) and a horizontal displacement of 12,030 m (39,469 ft)[3] - The previous world record was drilled and completed 30 March 2014 by the Yastreb land drilling rig in the Chayvo Field, Sakhalin-1 Project to a total measured depth of 13,000 m (42,653 ft) and a horizontal displacement of 12,130 m (39,797 ft) ## New developments New technologies have emerged that claim to be pushing the existing boundaries of ERD. One of these is the [\[1\]](https://uis.brage.unit.no/uis-xmlui/bitstream/handle/11250/183644/Uglebakken,%20Lars.pdf?sequence=1)Reelwell Drilling Method.[*[clarification needed](https://en.wikipedia.org/wiki/Wikipedia:Please_clarify)*] ## See also - [Underbalanced drilling](/source/Underbalanced_drilling) - [Well drilling](/source/Well_drilling) - [Drilling fluid](/source/Drilling_fluid) - [Lost circulation](/source/Lost_circulation) ## References 1. **[^](#cite_ref-1)** Kaiser, Mark J (2007-09-13) [Indices Describe Complexity of Drilling Directional, Extended-Reach Wells](http://www.redorbit.com/news/business/1064648/indices_describe_complexity_of_drilling_directional_extendedreach_wells/) *Red Orbit*, retrieved October 6, 2008 1. **[^](#cite_ref-2)** Negrao, Alvaro (May 2009) [Multilateral or Extended Reach](http://www.spe.org/jpt/print/archives/2009/05/JPT2009_05_15MERFocus.pdf) *SPE Website*, retrieved October 6, 2008, link updated May 1, 2013 1. **[^](#cite_ref-3)** [Sakhalin-1 sets new extended reach drilling record, Rosneft says](http://www.worldoil.com/news/2015/4/14/sakhalin-1-sets-new-extended-reach-drilling-record-rosneft-says), 2015 Authority control databases: National United States Israel --- Adapted from the Wikipedia article [Extended reach drilling](https://en.wikipedia.org/wiki/Extended_reach_drilling) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Extended_reach_drilling?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.