Energy From Shale: How It Works. Shale gas is natural gas trapped in hard, dense layers of sedimentary rock. The technology to tap into these deposits - known as fracking - is a combination of horizontal drilling and hydraulic fracturing developed over decades.
How Fracking (Hydraulic fracturing) Works: Graphic by David Butler, Javier Zarracina and Patrick Garvin. http://bostonglobe.com/business/2012/04/28/shale-gas-boom-has-benefits-and-risks/pbbY4kStbXH3kx9U2QKo1J/igraphic.html