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