1. A method of injecting a fluid into a subsurface formation, comprising: obtaining data including an initial set of formation parameters related to a subsurface formation; obtaining data including an initial set of operational variables related to an injection well in the subsurface formation; using non-transitory computer readable instructions with a computer processor to: develop a heuristic model for the injection well comprising a graph plotting data points representing (a) the ratio of the formation's effective shear strength to the in-situ geomechanical load, versus (b) the ratio of the hydraulic load placed on the rock formation to the formation's transmissibility potential at different sets of input parameters; correlate the data points to one or more regimes of operation selected from a group consisting of a formation fluidization regime, a formation fracture regime, or a matrix injection regime; and determine a regime of operation for the injection well using the heuristic model based at least in part on the obtained data; identifying designed operational variables for conducting injection operations based at least in part on the determined regime of operation; determining a completion design, reservoir development procedures, injection procedures, or combinations thereof based at least in part on the determined regime of operation; and conducting injection operations in an injection well utilizing the designed operational variables.