The "Superintendencia de Operaciones Orito Putumayo" is responsible for the exploitation of the Ecopetrol S.A. oil fields located in Putumayo and Nariño regions in southwest Colombia. The SOP is divided into five areas (Orito, Sur, Occidente, Nororiente, and Suroriente) covering over fifty fields of which sixteen fields are currently active. Economic evaluation of several mature oilfields of the SOP indicate that many operate at very close to the economic limit and in some cases the net present value are marginal and/or negative. It is for this reason that the "Superintendencia de Operaciones Putumayo" applied a Life Cycle Economic Analysis methodology whose objective was to estimate cash flow included in all phases of an investment life cycle. This includes design, construction, operation, maintenance, dismantling or conversion of this cash flow projected into the future and compared to similar investments. The evaluation considers the Net Present Value of the investment, including the installation of Nitrogen over Hydraulic pumping units in wells with variable characteristics and with high lifting cost. Lower capital acquisition cost, lower transport cost, lower installation cost and lower operation cost were confirmed. These results are being considered to optimize existing wells as well as improving economics for the drilling program in the western part of the region. Conclusions include an analysis of the impact on lifting cost of all fields.