Multi stage process for demetalation, desulfurization and {HEAD ~ dewaxing} of {TAIL ~ petroleum oils} 
Multi stage process for demetalation , desulfurization and { HEAD ~ dewaxing } of { TAIL ~ petroleum oils }
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL