Produced water re-injection (PWRI) is often the safest and most economical method for disposal of produced water in the oil industry. Two key issues that affect the management of PWRI are the formation damage and the constrained pumping pressure at the wellhead. A simulator was developed to handle the design of single-zone or multi-zone water injection in multilayered reservoirs. The simulator can accommodate both vertical and horizontal wells operated under matrix and/or fractured regimes. It is also able to account for the impact of formation damage and user-defined wellhead pressure constraints. Results obtained from the simulator showed good agreement with known injection behaviors. For vertical wells, injection conformance depends on KH (permeability-thickness) and the minimum horizontal stress; in the case of multi-fractured horizontal wells, the outermost fractures (those near the tip and the heel of the horizontal well) are longer than the fractures in the middle. Lastly, by constraining the maximum allowable surface pressure, frictional pressure drops in both the wellbore and fracture cause the injection rate to decline, which in turn affects both the fracture geometry and the maximum disposal volumes.