Amid a burgeoning decline in oil production in the reservoir, the tertiary phase of the oil production named enhanced oil recovery (EOR), especially chemical EOR, has gained some advantages. Conventional chemicals like surfactant combined with nanoparticles have emerged as a potential candidate to recover more oil. The heterogeneity in the reservoir is one of the main factors for oil production represented by Lorenz coefficient reflecting the distribution of permeability versus porosity or the degree of heterogeneity in a pay zone section. The heterogeneity data of the reservoir properties are required for reservoir simulation to control the oil production process of the reservoir. The aims of this research are to simulate the heterogeneous models of reservoir and to evaluate the effectiveness of nanoparticles combined with surfactant for EOR in the Northern oilfield in Thailand. For this study, 5 randomized data set with a fixed range of porosity and permeability value are used to calculate the Lorenz coefficient and applied to simulate the chemical injection process. The Lorenz coefficients range from 0.137 to 0.849. Also, the injection rates from 15.9 to 47.7 m3/d and the surfactant concentration from 1,000 - 4,000 ppm are the parameters that have been studied. The simulation results show that the Lorenz coefficients provide 17.91 % difference in oil recovery factor. Also, the efficiency of nanoparticles coupled with surfactant flooding can increase the recovery factor up to 67.97 %. The proper surfactant concentration is 2,000 ppm. An increase in injection rate can enhance the recovery factor up to 6.81 %. This research provides a significant scientific evaluation of heterogeneous factors in the structure of the reservoir. It will create further improvement of the process and the application of nanoparticles for injection flooding in the real field.