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 {HEAD ~ feedstock} in {TAIL ~ the solvent deasphalting} 
in
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 { HEAD ~ feedstock } in { TAIL ~ the solvent deasphalting }
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 OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL