Recovery of methane from {HEAD ~ the coal beds} can also be facilitated by the injection into the formation of an inert stripping {TAIL ~ gas} such as nitrogen 
Recovery of methane from { HEAD ~ the coal beds } can also be facilitated by the injection into the formation of an inert stripping { TAIL ~ gas } such as nitrogen
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH