Shale gas is natural gas extracted from dense shale rock formations. This is the foremost difference to regular natural gas that is extracted from more porous sandstone making it easier to extract as a whole. Large volumes of shale gas are already being extracted, primarily in the USA. In the future, shale gas may also become an important new source of gas within Europe. More than just drilling is required to extract shale gas. The rock formation also needs to be fractured in order to extract the natural gas locked inside it. This process involves pumping water, sand and other additives into the borehole under pressure. The implications of this type of gas extraction are currently being investigated. GasTerra is monitoring these developments very closely.