The instability of crude oil prices at the international market which results in revenue drop to oil and gas operators, the high cost of drilling multiple injection wells and installing gas reinjection systems in a bid to improve recovery of crude oil, have been of great concern to the Petroleum Industry. The Economic viability of Gas Reinjection for Enhanced Oil Recovery (EOR) (as against the gas flaring operation) was analyzed with 7 wells located onshore, in the Niger Delta region of Nigeria. The production history and reservoir data were gathered with which the cost analyses were conducted. Two scenarios involving seven production wells were evaluated. The first was converting two of the production wells to gas injection wells and producing from the remaining 5 production wells (IN2PROD5) and the other was injecting gas in two newly drilled injection wells and producing from the seven production wells (INJ2PROD7). It was shown that (INJ2PROD5) is a preferred option in extending the productive life of an otherwise depleted and uneconomic oilfield, having higher Net Present Value (NPV), Profitability Index (PI) and Internal Rate of Return (IRR) of -$53MM, 0.93 and 27.40% while the INJ2PROD7 had $161MM, 1.39 and 37.75% at discounted rate of 30% respectively. After subjecting the expected net revenues under various crude oil price sensitivity market vagaries, INJ2PROD5 will stand the test of time as it is less expensive and yielded a higher gross profit which is the major factor in any investment decision making.