A method of predicting earth stresses in response to changes in a hydrocarbon-bearing reservoir within a geomechanical system includes establishing physical boundaries for the geomechanical system, acquiring logging data from wells drilled, and acquiring seismic data for one or more rock layers. The well and seismic data are automatically converted into a three-dimensional digital representation of one or more rock layers within the geomechanical system, thereby creating data points defining a three-dimensional geological structure. The method also includes (a) applying the data points from the geological structure to derive a finite element-based geomechanical model, and (b) initializing a geostatic condition in the geomechanical model, and then running a geomechanics simulation in order to determine changes in earth stresses associated with changes in pore pressure or other reservoir characteristics within the one or more rock layers.