The KKR money prompted Hilcorp to add four more horizontal rigs, bringing its total to six and allowing it to drill over 40 horizontal wells.

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You drill two horizontal wells and inject steam into the upper one, draw bitumen by gravity into the lower well and bring it to the surface.

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Drillers also use sensors to detect particularly promising rock intervals within the formation, and are able to move the drill string up or down, left or right as they drill through the horizontal section to target those intervals.

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The report suggests that any shale gas development outside of the United States is likely five to ten years away, primarily because many of the countries that could benefit from shale production do not have the specialized equipment needed to drill and frack horizontal wells.

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Horizontal Drilling now allows these same operators to drill and set pipe for a mile or more horizontally through this same rock formation.

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Shales are tough to drill, necessitating wells with lots of horizontal laterals snaking their way into thin pay zones.

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According to a 2009 Congressional Research Service report on unconventional gas shales, directional drilling (sometimes referred to as horizontal drilling) allows for access beyond the area below the drill to both oil and gas reserves in locations inaccessible to conventional drilling, including to difficult to reach offshore reserves.

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