The method 4 wherein {HEAD ~ the amount} of hydrogen introduced into said coal bed formation is within {TAIL ~ the range} of 0.2–1.0 standard cubic feet for each cubic foot of methane recovered from said coal bed formation 
The method 4 wherein { HEAD ~ the amount } of hydrogen introduced into said coal bed formation is within { TAIL ~ the range } of 0.2–1.0 standard cubic feet for each cubic foot of methane recovered from said coal bed formation
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH