1. A method of performing a fracture treatment on a naturally fractured subterranean formation, said method comprising: acquiring subterranean formation layer geomechanical properties comprising well completion and reservoir data for the subterranean formation, and a natural fracture network description for the subterranean formation; inputting geomechanical properties of the formation into a model; simulating propagation of a network of fractures in the formation; predicting if each fracture will grow and in which direction the fracture will branch; predicting a flow rate and pressure distribution throughout the network of fractures by solving governing deformation and flow equations; predicting a result of a design of the fracture treatment; and adjusting the design if the predicted result is not satisfactory.