{TAIL ~ The deasphalting residue} is then added to a second portion of {HEAD ~ heavy oil}, such as a second portion of the same type of heavy oil that was used as feedstock in the solvent deasphalting 
{ TAIL ~ The deasphalting residue } is then added to a second portion of { HEAD ~ heavy oil } , such as a second portion of the same type of heavy oil that was used as feedstock in the solvent deasphalting
TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH 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 OTH OTH OTH OTH OTH OTH