{HEAD ~ At least one common well} is used for recovery of methane from the formation and introduction of hydrogen into {TAIL ~ the formation} 
{ HEAD ~ At least one common well } is used for recovery of methane from the formation and introduction of hydrogen into { TAIL ~ the formation }
HEAD HEAD 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 TAIL