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