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