Compared with theformer, the inclusion in the latter was characterized by its complex assemblage intypes, andhigherhomogenizationtemperature, salinityandtrappedpressure.
About 25, 000 wells a year are being fracked, a process in which water, chemicals and sand are injected at high pressure underground to release trapped natural gas.
The process involves pumping water containing small percentages of other materials into the porous shale under pressure to hydraulically fracture it and release the trapped oil and gas.