The injection of {TAIL ~ hydrogen} is carried out under {HEAD ~ a pressure} sufficient to cause the injected hydrogen to become absorbed within the matrix of the carbonaceous formation 
The injection of { TAIL ~ hydrogen } is carried out under { HEAD ~ a pressure } sufficient to cause the injected hydrogen to become absorbed within the matrix of the carbonaceous formation
OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH