PROCESS

The present invention provides a process for simultaneously extracting and upgrading a heavy hydrocarbon mixture, said process comprising: i) injecting supercritical or near-supercritical CO2 at a temperature of around the critical temperature and a pressure of from around the critical pressure into a heavy hydrocarbon deposit; and ii) removing a stream of CO2 from the deposit, which stream is charged with a hydrocarbon mixture having a lower average molecular weight than that of the heavy hydrocarbon deposit, wherein the removed CO2 is optionally recovered and either recycled for subsequent re-injection or injected for long-term sub-surface storage.