Waterflooding is a secondary recovery method widely used in the oil industry implemented with the purpose of increasing additional oil recovery from oil reservoirs. Traditionally the waterflooding projects are implemented by means of injecting water through water injector wells in order to maintain or improve the reservoir pressure and to sweep the oil towards the producer wells. The purpose of this work is to present a novel waterflooding alternative called natural waterflooding. This natural waterflooding method attempts to use the water and energy from a higher pressure reservoir to a lower pressure reservoir. The natural waterflooding method will be implemented to La Peña reservoir of La Peña Field throughout a crossflow system of the water coming from Bolivar reservoir of the same field. In this field La Peña reservoir (upper reservoir) is being depleted naturally and we want to avoid the pressure to fall too far below the bubble point. At the same time the waterflood will be used to sweep the oil from the lower parts of the reservoir toward the wells located in the upper part of the reservoir. The Bolivar reservoir (lower reservoir) has a strong water drive system that has sustained the reservoir pressure in the order of 150 psi below the initial reservoir pressure (3750 psi) for more than 20 years of explotation. Currently exists 1500 psi of pressure difference between these two reservoirs. In this work we describe the overall project and the several stages to be tested before the full field implementation. We also include the favorable expected economic impact of this method compared to the classic waterflooding. At this moment the laboratory tests have been performed and are explained. Nodal analysis applied to the water production system of the Bolivar reservoir and to the water injection of the La Peña reservoir was performed in order to determine the water rate that will enter into La Peña reservoir. Also the varation of the rate due to the pressure increase in La Peña reservoir with time is considered. Currently we are at the pilot project stage implementation. Field work consists in the workover for the pilot project and is the next operating step. Field tests are part of the next steps and their design are described in detail.