The performance, i.e. the half-life of water injectors, is very important to the economics of water injection projects. A simulator is presented to predict the decline in injectivity of water injection wells. Equations are presented that allow us to model open-hole and perforated completions as well as fractured wells. The mechanism of injectivity decline can be determined by comparing core flow test data with one of four type curves. The transition time is used to determine when external filtration becomes dominant so that the appropriate models can be used for early and late time.

The simulator can be used whether or not core flow data is available. Empirical equations are provided to estimate the filtration parameters if core flow test data is not available. The simulator is easy to use, has interactive input and output and is available for PCs and Unix workstations. Examples are provided to show how the simulator can be used to predict the performance of injectors in a variety of cases. The simulator predictions are compared with experimental data. The simulation results are then used to suggest the optimum water quality that will minimize the total cost of water treatment and periodic well stimulation.