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