In situ combustion (ISC) in a one-dimensional combustion porous tube has been modeled numerically and presented in this article. The numerical model has been developed using the cmg stars (2017.10) software and it was used to model especial cases for validation against published experimental data. A comprehensive chemical reaction scheme has been developed and used to simulate the ISC process in the lab scale. Moreover, co-injection of oxygen with carbon dioxide (O2/CO2); and co-injection of enriched air (O2/N2) have been further investigated. In the case of using (O2/N2) as an oxidizer, increasing the oxygen ratio from 21% to 50% leads to increasing the oil recovery factor from 31.66% to 66.8%, respectively. In the case of using (O2/CO2) as an oxidizer, increasing the oxygen ratio from 21% to 50% leads to increasing the oil recovery factor from 35.77% to 70.3%, respectively. It was found that the co-injection of (O2/CO2) gives higher values of the oil recovery factor compared with that given when oxygen-enriched air (O2/N2) is injected for ISC. The change in the produced cumulative hydrogen and hydrogen sulfide is considered small whether using (O2/CO2) or (O2/N2) as an oxidizer.