Patent ID: 7186876

Claim:
A process for preparing a process oil with an aromatic content of more than about 50 wt % and a polycyclic aromatics content less than about 3 wt % wherein said process comprises: utilizing a countercurrent liquid-liquid extraction column for the solvent extraction of a first petroleum fraction feedstock boiling in the lubricating base oil range to yield an aromatic rich hydrocarbon fraction; after the utilizing step, contacting a feed mixture, including a second petroleum fraction feedstock boiling in the lubricating oil range and said aromatic rich hydrocarbon fraction, wherein the mass ratio of the second petroleum fraction feedstock boiling in the lubricating oil range to the aromatic rich hydrocarbon fraction is between 3:1 and 1:3, and wherein the aromatic rich hydrocarbon fraction has a kinematic viscosity at 100° C. from about 12 cSt to about 30 cSt and an aromatic content of from about 50 wt % to about 90 wt %, with a polar solvent in the counter current liquid-liquid extraction column to produce a top product and a bottom product;) removing the polar solvent from the top product to obtain the process oil; and,) removing the polar solvent from the bottom product to obtain an extract.