An environmentally-benign supercritical fluid route is developed to demulsify and treat highly intractable petroleum emulsions containing hazardous acidic compounds, heavy fractions, heteroatoms, and metallic impurities without using external catalysts and molecular hydrogen. The produced synthetic crude oil exhibits asphaltene-free fractions with low amounts of impurities, which could be suitable for use in current petroleum refineries. The degree of reductions of asphaltenes and non-distillate fraction are 98.5% and 94.0%, respectively. The deacidification tendency of supercritical methanol results in 90.2% reduction of total acid number. Ni, Ca, and N are removed below detection limits (0.1 ppm for Ni/Ca and 0.01 wt% for N). V and S are reduced with efficiency of 85.0% and 33.6%, respectively. (C) 2017 Elsevier Ltd. All rights reserved.