The effect of Enhanced Oil Recovery (EOR) system during the simulation of oil displacement in porous media in the laboratory on the composition of heavy oil from the Usinskoye oil field of Russia was investigated. It is shown that in the course of its displacement by water and surfactant composition from the model of reservoir of different permeability, 53 – 54 rel  %  of the residual oil remains on the core material. Using the methods of chromatography on silica gel in a Soxhlet apparatus and chromato – mass – spectrometry (GC-MS) we have determined the changes of the component composition of oil passed through the pore space of rock sample (DOS) and those of non-recovered residual oil (ROS). It was found that the composition of the combined oil sample (DOS) after displacement by water, as well as with the use of compositions, is characterized by a slight increase in the alkane content (from 68 to 72% rel.). The proportion of aromatic and naphthenic hydrocarbons in the sample of DOS in comparison with the original sample (MOS) decreased by an average of 1.2 times. In the residual oil (ROS) there is an increased content of resins and asphaltenes. The content of alkanes in the residual oil decreased by 3 times, while the total content of saturated cyclic hydrocarbons increased by 3.2-3.6 fold, aromatic compounds - 2 times.