Shale gas

Shale gas is a type of gas trapped in rock formations, however the formations are different than in the case of conventional gas-bearing reservoirs. Natural gas in clay minerals, commonly referred to as shales, is created in the same manner as conventional gas, namely through decomposition of organic matter in high temperatures and at large depths.

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It can form in rock layers with a high content of organic material. Some of the gas escapes from the rock (conventional gas), and some of it remains trapped in the rock – the less permeable the rock, the more gas is trapped. Shales, which are encountered in many regions of the world, have very low permeability, which is why they are a rich source of unconventional gas. Composition of shale gas is similar to that of natural gas in conventional reservoirs. It contains methane (75 – 95%) and nitrogen, and sometimes trace quantities of ethane, propane, the noble gases, oxygen and carbon oxide. However, no traces of harmful hydrogen sulphide have been found in shales.

Shale gas may prove to be a major game-changer on the European energy market, as a large source of fuel set to play a key role in the low-carbon future.