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