The research for tomorrow's oil reserves has directed the efforts of the energy industry to frontiers beyond the conventional exploration and production strategies. Frontier defined not by geography or geology but rather by technology. This frontier is a collection of technologies-involving the use of thermal, gas and chemical means for producing more oil-that fall under the broad umbrella called Enhanced Oil Recovery (EOR). The results of successful application of this new technology will have a decisive impact on the energy conservation program of any oil producing country. A comprehensive national energy program is complex and to plan it represents a challenge. A unified and complete national program must encompass the consideration of all possible options. The potential of each need to be explored. One such option in Libya is to produce more oil, that is, to effect the enhancement of oil recovery from the nation oil fields. The planning of an EOR project demands a meticulous attention to many problems, thus requiring considerable lead time for studies, evaluations, project design and most of all the economics of these high cost EOR projects. The objective of this study is to conduct an economic analysis on one of the most representative candidate major field in Libya (D field) for application of the technically approved Enhanced Oil Recovery methods. By performing economic sensitivity analysis on key input variables such as oil prices, the price of injection solvent, capital expenditures, operating expenses, and oil recovery with the aim to develop sensitivity analysis graphs for each variable to assess future engineering planning with regard to the EOR projects economics in Libya. Economic optimisation is the ultimate goal of reservoir engineering management. With estimated production, capital, operating expenses, and financial data, project economics are evaluated. Project finding could be applied to any EOR candidate reservoir worldwide.