A computer-implemented method for use in modeling a geomechanical reservoir system, comprising: receiving, through a computer system, data indicative of physical properties associated with the geomechanical reservoir system; characterized in that the method further comprises: generating, through a computer system, fracturing predictions by solving a system of partial differential equations that model the geomechanical reservoir system; wherein the system of partial differential equations comprises a reservoir flow model, a geomechanical model, and a fracture model of the geomechanical reservoir system; wherein the system of partial differential equations are coupled through a fully-expanded Jacobian which is generated for the full system of partial differential equations; wherein the solving of the system of partial differential equations comprises solving simultaneously in a single timestep a linear system of equations corresponding to the fully-expanded Jacobian based upon the received physical properties data; and wherein the fracturing predictions model the geomechanical reservoir system for the timestep; and outputting or displaying, through a computer system, the generated fracturing predictions. receiving, through a computer system, data indicative of physical properties associated with the geomechanical reservoir system; characterized in that the method further comprises: generating, through a computer system, fracturing predictions by solving a system of partial differential equations that model the geomechanical reservoir system; wherein the system of partial differential equations comprises a reservoir flow model, a geomechanical model, and a fracture model of the geomechanical reservoir system; wherein the system of partial differential equations are coupled through a fully-expanded Jacobian which is generated for the full system of partial differential equations; wherein the solving of the system of partial differential equations comprises solving simultaneously in a single timestep a linear system of equations corresponding to the fully-expanded Jacobian based upon the received physical properties data; and wherein the fracturing predictions model the geomechanical reservoir system for the timestep; and outputting or displaying, through a computer system, the generated fracturing predictions. generating, through a computer system, fracturing predictions by solving a system of partial differential equations that model the geomechanical reservoir system; wherein the system of partial differential equations comprises a reservoir flow model, a geomechanical model, and a fracture model of the geomechanical reservoir system; wherein the system of partial differential equations are coupled through a fully-expanded Jacobian which is generated for the full system of partial differential equations; wherein the solving of the system of partial differential equations comprises solving simultaneously in a single timestep a linear system of equations corresponding to the fully-expanded Jacobian based upon the received physical properties data; and wherein the fracturing predictions model the geomechanical reservoir system for the timestep; and wherein the system of partial differential equations comprises a reservoir flow model, a geomechanical model, and a fracture model of the geomechanical reservoir system; wherein the system of partial differential equations are coupled through a fully-expanded Jacobian which is generated for the full system of partial differential equations; wherein the solving of the system of partial differential equations comprises solving simultaneously in a single timestep a linear system of equations corresponding to the fully-expanded Jacobian based upon the received physical properties data; and wherein the fracturing predictions model the geomechanical reservoir system for the timestep; and outputting or displaying, through a computer system, the generated fracturing predictions.