Performing a well operation based upon a minimum in-situ stress determination

A system of performing a well operation including determining a minimum horizontal in-situ stress of a subterranean formation, comprising: a first component configured to create a measured pressure response from data of a well injection test; a simulation component configured to generate a simulated pressure response with a selected value of a simulated minimum horizontal in-situ stress; and an arrangement to compare at least a portion of the simulated pressure response to a corresponding portion of the measured pressure response to resolve a difference; whereby the minimum horizontal in-situ stress of the formation may be equated to a value of the simulated minimum horizontal in-situ stress corresponding with a lesser resolved difference. Further aspects of the disclosure include novel methods.