This work proposes a new system to perform the water injection for pressure maintenance in offshore fields without the need of installing additional facilities for water treatment. The main objective is to directly communicate an active aquifer with the depleted reservoir through existing vertical or deviated wells, of which trajectories enable the completion in both formations. It takes advantage of the pressure support from the aquifer, thus, avoiding the requirement of additional infrastructure. It is an artificial crossflow between two formations, where the water-injection rates will basically depend on two parameters: the formations flow capacity and the pressure difference between the aquifer and the reservoir. The injectivity indexes of the communicating wells can be determined using a combination of pressure drop equations. Finally, an example of possible application in an offshore field is presented; the analysis indicates that its implementation would carry many benefits in a short period of time.