A heavy hydrocarbon mixture represented by C-17-C-31 carbon groups was investigated to determine extraction recoveries by supercritical carbon dioxide in the ranges of 12-65 MPa for pressure and 50-90 degrees C for temperature. The purpose of the study was to obtain a three-dimensional scheme of the SC-CO2/heavy hydrocarbon mixture system in pressure-temperature-recovery coordinates, which allows the prediction and numerical modeling of phase behavior. At lower temperatures, high recoveries were attained at lower pressures. The highest recovery of 93% was obtained at 70 degrees C and 56 MPa. The recoveries greater than 65% were determined at the breakover points where the pressure increased by 7 MPa with a temperature increase of 10 degrees C. The phase envelope, 3D scheme, and the equations describing the boundaries of the system are presented.