Nowadays the share of hard-to-recover reserves is growing, and to maintain oil production on necessarily level, we need to involve hard-to-recover reserves or to increase oil production efficiency on a brownfields due to enhanced oil recovery. The efficiency of enhanced oil recovery can be estimated by oil saturation reduction. Single-well-chemical-tracer-test (SWCTT) is increasingly used to estimate oil saturation before and after enhanced oil recovery application. To interpret results of SWCTT, reservoir simulation is recommended. Oil saturation has been calculated by SWCTT interpretation with use of reservoir simulator (CMG STARS). Distribution constants has been corrected due to results of real core sample model, and core tests has been successfully simulated. Obtained values of oil saturation corresponds with real oil saturation of samples. Thus, SWCTT as a method of oil saturation estimation shows good results. This method is promising for enhanced oil recovery efficiency estimation.