The Shushufindi field is the largest in Ecuador's Oriente basin. It was discovered by Texaco in 1970 and has produced more than 1 billion bbl of oil. Early in the life of the field, peripheral water injection was implemented, but it was discontinued in 1999 on the basis of a reservoir-simulation study carried out in late 1999. Currently, the field is producing a significant amount of water under a very active waterdrive mechanism. This paper presents the results of a new integrated reservoir study that was performed to optimize the field performance for effective reservoir management.