Horizontal drilling

From Wikimarcellus

In order to tap natural gas with horizontal drilling typically a drill is sent down vertically a mile or so underground and then turned at a ninety degree angle horizontally into the shale. The shale tends to be located between approximately five and eight thousand feet below ground.

Horizontal wells are much more expensive to drill than vertical ones. Costs may run between $4 million and $7 million U.S. for a horizontal shale well. Vertical wells can be drilled for only $1-2 million U.S.

Reusable drilling rigs that cost up to $16 million apiece are generally used for horizontally drilling Marcellus shale wells.