Horizontal drilling
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| *[http://en.wikipedia.org/wiki/Directional_drilling - ''Wikipedia'' on directional drilling] | *[http://en.wikipedia.org/wiki/Directional_drilling - ''Wikipedia'' on directional drilling] | ||
| - | *[http://www.chiefog.com/drilling_process.html - Video on horizontal drilling] and [[Hydro-fracturing|hydro-fracturing]] produced by [[Chief Oil and Gas]].] | + | *[http://www.chiefog.com/drilling_process.html - Video on horizontal drilling] and [[Hydro-fracturing|hydro-fracturing]] produced by [[Chief Oil and Gas]]. |
Revision as of 23:07, 22 April 2009
Horizontal drilling is a form of directional drilling. In order to tap natural gas typically a drill is sent down vertically a distance up to a mile or so underground and then turned at a ninety degree angle horizontally into the shale. By using horizontal drilling the drill bit can penetrates a much greater number of pockets of natural gas than it ever could with vertical drilling. On the average horizontal wells produce three to five times the amount of natural gas from vertical ones.
The shale tends to be located between approximately five and eight thousand feet below ground although it can be at even greater depth.
Horizontal drilling rigs can drill down up to 10,000 feet vertically to the Marcellus or other shale, and then are turned horizontally for several thousand additional feet. Well pads are around 5 acres with up to 6 horizontal wells stemming from the same pad.
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 ones 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. These rigs are larger-sized ones with 1,000 and 1,600 horsepower.
A business strategy sometimes employed is to drill a vertical well that can produce up to $700,000 per day in production. This can be done fairly inexpensively to get some scientific data about the acreage, and then go back in later with a horizontal portion of the well using a larger rig.
