Shale production on a significant scale arose quite recently and is so far limited to the US with gas having a few years' lead on oil. Shale has already had a significant impact on US gas and oil output. Further sizable production increases can be expected in the US, and the shale revolution is likely to spread, with a lag, across the globe. This will result in fundamental repercussions for international energy markets. The resources in focus of our attention, comprising shale gas and coalbed methane along with tight gas and tight oil, typically lack strict definitions and they often overlap. However, they are all characterized by low permeability that yields commercially insufficient flows from vertical drilling. The shale revolution is the result of technological breakthroughs in horizontal drilling and hydraulic fracturing that have made vast dormant gas and oil resources economically exploitable