Editing Directional drilling (section)

==Disadvantages==
[[File:Figure 4- Example of a Horizontal Wellbore Traversing Mineral Parcels with Different Owners (13985529998) (cropped).jpg|thumb|upright=1.5|[[Government Accountability Office]] depiction of horizontal drilling being used to cross tracts of land with differing owners]]
Until the arrival of modern downhole motors and better tools to measure inclination and azimuth of the hole, directional drilling and horizontal drilling was much slower than vertical drilling due to the need to stop regularly and take time-consuming surveys, and due to slower progress in drilling itself (lower rate of penetration). These disadvantages have shrunk over time as downhole motors became more efficient and semi-continuous surveying became possible.

What remains is a difference in operating costs: for wells with an inclination of less than 40 degrees, tools to carry out adjustments or repair work can be lowered by gravity on cable into the hole. For higher inclinations, more expensive equipment has to be mobilized to push tools down the hole.

Another disadvantage of wells with a high inclination was that prevention of sand influx into the well was less reliable and needed higher effort. Again, this disadvantage has diminished such that, provided sand control is adequately planned, it is possible to carry it out reliably.

===Stealing oil===
In 1990, [[Iraq]] accused [[Kuwait]] of stealing Iraq's oil through slant drilling.<ref>{{cite web|title=How the Gulf Crisis Began and Ended (The Gulf Crisis and Japan's Foreign Policy)|url=http://www.mofa.go.jp/policy/other/bluebook/1991/1991-2-1.htm|publisher=Ministry of Foreign Affairs of Japan|access-date=28 January 2014}}</ref>
The [[United Nations]] redrew the border after the [[Gulf War|1991 Gulf war]], which ended the seven-month [[Invasion of Kuwait|Iraqi occupation]] of Kuwait. As part of the reconstruction, 11 new oil wells were placed among the existing 600. Some farms and an old naval base that used to be in the Iraqi side became part of Kuwait.<ref>{{cite web | url=http://abclocal.go.com/wabc/story?section=news/national_world&id=3413018 | title=Iraq to Reopen Embassy in Kuwait | publisher=[[ABC Inc.]] | date=4 September 2005 | access-date=5 March 2012 | archive-url=https://web.archive.org/web/20140102194548/http://abclocal.go.com/wabc/story?section=news%2Fnational_world&id=3413018 | archive-date=2 January 2014 | url-status=dead }}</ref>

In the mid-twentieth century, a slant-drilling scandal occurred in the huge [[East Texas Oil Field]].<ref>{{cite web | author = Julia Cauble Smith | title = East Texas Oilfield | url = https://tshaonline.org/handbook/online/articles/doe01 | access-date = 2014-09-23 | work = Handbook of Texas Online | publisher = Texas State Historical Association | date = 2010-06-12}}</ref>

===New technologies===
Between 1985 and 1993, the Naval Civil Engineering Laboratory (NCEL) (now the [[Naval Facilities Engineering Service Center]] (NFESC)) of Port Hueneme, California developed controllable horizontal drilling technologies.<ref>[http://apps.dtic.mil/dtic/tr/fulltext/u2/a274219.pdf Horizontal Drilling System (HDS) Field Test Report - FY 91]</ref> These technologies are capable of reaching {{convert|10,000|–|15,000|ft|m|abbr=on}} and may reach {{convert|25,000|ft|m|abbr=on}} when used under favorable conditions.<ref>{{Cite web |url=http://www.stormingmedia.us/21/2119/A211962.html |title=Horizontal Drilling System (HDS) Operations Theory Report |access-date=31 August 2008 |archive-date=31 May 2009 |archive-url=https://web.archive.org/web/20090531101855/http://www.stormingmedia.us/21/2119/A211962.html |url-status=dead }}</ref><!--Note: The foot measurements are original; the m are converted and rounded-->