In conventional fluid flow formulations, the pore volume variation only depends on the pore volume compressibility coefficient. The rock compressibility is assumed to be constant and the reservoirA subsurface body of rock with sufficient porosity and permeability to store and transmit fluids permeabilityAbility to flow or transmit fluids through a porous solid such as rock is unaffected by pore pressure changes. However, the injectionThe process of using pressure to force fluids down wells of CO2Carbon dioxide, especially into highly compacted, faulted and fractured formations, causes a strain localisation on fractureAny break in rock along which no significant movement has occurred and fault(geology) A surface at which strata are no longer continuous, but are found displaced planes and results in a change in permeabilityAbility to flow or transmit fluids through a porous solid such as rock or transmissibility. To account for geomechanical effects due to stress changes in and around the injectionThe process of using pressure to force fluids down wells formationA body of rock of considerable extent with distinctive characteristics that allow geologists to map, describe, and name it, the fluid flow problem must be solved with a geomechanical model that can predict the evolution of stress dependent parameters, such as porosityMeasure for the amount of pore space in a rock, rock compressibility, and permeabilityAbility to flow or transmit fluids through a porous solid such as rock. The coupling can be carried out by integrating the mechanical concepts in reservoirA subsurface body of rock with sufficient porosity and permeability to store and transmit fluids simulation. The geomechanical equilibrium equation and the fluid mass balance equation should be solved iteratively. In the case of highly compacted, faulted and fractured reservoirs, the coupling may also lead to a modification of the transmissibility matrix due to fractureAny break in rock along which no significant movement has occurred and fault(geology) A surface at which strata are no longer continuous, but are found displaced permeabilityAbility to flow or transmit fluids through a porous solid such as rock enhancement resulting from rock deformation (Longuemare et al., 20022002 - P. Longuemare, M. Mainguy, P. Lemonnier, A. Onaisi, C. Gerard and N. KoutsabeloulisGeomechanics in reservoir simulation: overview of coupling methods and field case studysee more).
The fully coupled and partially coupled approaches can be used to solve the stress dependent CO2Carbon dioxide geological storage(CO2) A process for retaining captured CO2, so that it does not reach the atmosphere problem.
The fully coupled approach simultaneously solves the whole set of equations in one simulator. The fully coupled method offers internal consistency for the simultaneous resolution of both flow and stress equations, but the hydraulic or geomechanical mechanisms are often simplified by comparison with conventional uncoupled geomechanical and reservoirA subsurface body of rock with sufficient porosity and permeability to store and transmit fluids approaches. TOUGH-FRAC, a simulator for non-isothermal multiphase flow in porous media with geomechanical coupling, is an example of such a code which models plume dispersion and impact of stresses due to CO2Carbon dioxide interactions.