Additives for supercritical water process to upgrade heavy oil

A system for upgrading a petroleum feedstock, the system comprising:

• a disulfide oil unit, the disulfide oil unit is operable to produce a disulfide oil from a disulfide oil unit feed, where the disulfide oil comprises disulfides, wherein the disulfides comprise sulfur-containing compounds of the form Ci-SS-Cj, where C refers to carbon, where S refers to sulfur, where i is selected from 1, 2, 3, 4, 5, and 6, where j is selected from 1, 2, 3, 4, 5, and 6, wherein the disulfide oil comprises a total sulfur content of greater than 30% by weight;
• a supercritical water upgrading unit, the supercritical water upgrading unit operable to produce a product gas stream, a product oil stream, and a used water stream from a mixed petroleum stream comprising the disulfide oil and a petroleum feedstock, wherein a supercritical water reactor of the supercritical water upgrading unit is operated at a temperature between 380 deg C. and 600 deg C. and a pressure in the range between 3203 psig and 5150 psig.