Stimulate rather than fracture
Gas coal has nothing of a novelty. "Former miners know him well, evidenced Raymond Michels, a geochemist at the laboratory ETE. And for good reason: it's firedamp dreaded the time when we operated the coal . EnjoyColoring.com The gas trapped in the structure of coal, was freed unexpectedly when digging galleries ... " Today the mines are closed, the idea is to go for systematically this natural resource in the layers of deepest coal, that have never been exploited by mining companies because of their inaccessibility: usually more than one kilometer below ground .
To do this, a technology - unique in Europe - has been developed in North America and Australia, where coal gas is already being exploited: the stimulation . Nothing to do with hydraulic fracturing used to extract shale gas , say the researchers. In the case of fracturing, it sends large amounts of water (and appropriate additives) to create a fracture pressure of the rock and in which the gas is trapped. In the case of coal gas, it is instead to create a depressurization. "We pump the water naturally present in the rock, and the lack of pressure created forces the gas out of the microcracks coal," said Raymond Michels.
Exploration drilling gas, European Gas Limited, in 2009 Folschviller
Exploration drilling gas, EGL, in Folschviller in 2009 © T.Sanchis, The Republican Lorrain Maxpp