In this research, three suitable alkanolamine solutions are selected for sweetening a natural gas with high H2S content and low CO2/H2S ratio. For each process, six different CO2 fractions in the regenerated solution are selected. On the basis of each CO2 fraction in the regenerated solution, the three processes are designed and simulated using the Aspen HYSYS process simulator to rich pipeline specifications (i.e., H2S content lower than 4 ppm and CO2 content lower than 2 mol %) for the sweet gas. The results of simulation are then economically evaluated using Aspen Economic Evaluation software. The results of simulation and economic evaluation indicate that the diglycolamine (DGA) process is more economical compared to monoethanolamine (MEA) and mixed methyldiethanolamine (MDEA) + MEA processes. Also, it is concluded that there are several advantages in operating the alkanolamine sweetening processes at higher CO2 fractions of the regenerated amine. On the basis of the results of this study, lower total capital costs, lower annual operating costs, and lower energy requirements for regeneration of the solution are obtainable by operating the alkanolamine sweetening processes at higher fractions of CO2 in the regenerated solution.