Iraq S reservoir is a typical tight oil reservoir with considerable reserves. Multi stage fracturing horizontal wells exhibit steep decline rates and yield low recovery factors. Enhanced oil recovery in such tight reservoirs has received increasing attention. The utilization of gas has proven to be effective among various enhanced oil recovery methods. This paper reveals a feasibility study investigating the application of gas for enhanced oil recovery from S reservoir. Nitrogen, carbon dioxide, and hydrocarbon gas were evaluated through experimental methods. The minimum miscible pressure (MMP) was firstly determined, and micro oil displacement differences were highlighted to carry out gas displacement tests. Gas drive and gas Huff n Puff were comparatively studied and the injection strategies that yield the best EOR performance were finally provided. The simulation outcomes verified that oil recovery improved significantly by gas injection. Under current reservoir conditions, carbon dioxide and hydrocarbon gas can achieve miscible, while nitrogen cannot. NMR experiments showed that the breakthrough time of gas in miscible drive was significantly delayed, and more gas entered small pores, enhancing the degree of utilization, resulting in a significantly higher recovery rate of CO2 and hydrocarbon gas than that of N2 immiscible drive. For miscible flooding, the higher the injection pressure, the slower the injection rate, and the better the recovery effect. Pulse injection was better than continuous injection. For immiscible flooding, using Huff and Puff was more advantageous. To our knowledge, there are lots of similar tight oil reservoirs with enormous commercial potential in Middle East. The research results have confirmed the technical feasibility of different gas recovery methods. In regard to some uncertainties, the paper also proposed some key factor studies for the operator to consider in the next stage.