In one of Chubutś main secondary recovery project, with great impact on production and reserves in El Trébol field, Proved Developed on Production Reserves suffered a strong discount. A multidisciplinary team was formed that made a diagnosis based on Monitoring and Surveillance techniques and proposed a short, medium and long term development plan. The first phase consisted in an immediate action plan to reverse the projectś strong decline rate and shield reserves, with low associated investment. In a second phase, actions were planned at a well-pattern level and 40 infill wells were drilled. In the third phase, the previous results were analyzed and the static model was revisited, a new calculation of OOIP was made. In this last phase, 34 more wells were drilled, which enabled an increase in recovery factors of the main blocks in the project. These actions not only avoided the loss of production, but also allowed an increase in EUR, an incorporation of reserves, and a future development plan for the field was defined. Instantaneous flow rate of oil increased by 33% at its maximum peak. Pushing the recovery factor in an asset in which development began in 1938 was not challenge free, it took several years of sustained commitment and multidisciplinary team work. In this paper workflow and results will be presented.