Process for upgrading heavy crude oil production

A process for upgrading a heavy, high viscosity, crude oil/water emulsion containing water, solids, and impurities comprising heavy metals, asphaltic, asphaltenic and resinous materials, which process comprises the steps of:

• removing gross solids from said crude-oil/water emulsion;
• adding a light hydrocarbon diluent to the crude oil emulsion to form a mixture containing said crude-oil/water emulsion and said diluent;
• pressurizing and heating said mixture;
• flashing said heated mixture under such conditions to vaporize a sufficient amount of said mixture to break the crude oil emulsion and to form a vapor effluent containing said diluent, water, crude oil and some entrained solids and a liquid effluent containing said diluent, water, crude oil and solids;
• separating said crude oil and asphaltic and alphaltene materials in said liquid effluent from water, solids and impurities,
• adding additional diluent to the liquid effluent after the flashing step, using 200 to 800 volume percent based on the separated oil content, selecting the diluent from the group of C.sub.4 through C.sub.7 paraffinic or naphthanic hydrocarbons at a moderate temperature of 60.degree. to 100.degree. F. to obtain a continuous single phase oil-diluent solution;
• gently warming the oil-diluent solution to a temperature within about 5.degree. F. to about 25.degree. F. of the critical temperature of the diluent causing a substantial part of the asphaltic or asphaltenic content of the crude oil to precipitate, causing the asphaltic solid or semi-solid material to settle from the lighter oil-diluent solution;
• separating the diluent from the oil for recycling;
• and
• recovering the crude oil product.