A New Tool to Predict Injection Well Number for a Total Injection Rate and Given Formation Properties

This study presents a simple and fast method to determine the injectivity of saline formations. The method uses a database of estimates of maximum injectivity generated using a commercial compositional numerical simulator for different hypothetical, but representative saline formations. Several hundred cases are created by altering formation thickness, permeability, relative permeability, area, depth and porosity. The formation and fracture pressures are calculated using hydrostatic pressure and fracture pressure gradients. In order to account for multi-well injection effects such as pressure interference, four different injection well numbers (1, 4, 16 and 64) are used. Sets of type curves are generated using the database to find maximum injectivity and the required number of injection wells for given sets of formation properties and total injection rate. Reflecting the fact that reservoir properties are uncertain, we also incorporate Mont Carlo simulations to derive probability distributions of injectivity and well numbers.