Abstract
Coupled reservoir flow and geomechanics receives a growing research
interests for applications in unconventional oil & gas recovery and
geological CO2sequestration. For CO2 sequestration, accurate prediction
of the behavior of the injected CO2 is important to the long-term
success of the sequestration because even small leakage rates over long
time periods can unravel the positive outcomes of net CO2 sequestered.
Furthermore, the effect of high rates of injection of CO2 on natural
fractures is crucial in determination of earthquake effects. High
fidelity multiphysics models are needed to simulate these processes and
their interactions accurately and efficiently to ensure the success and
safety of the operations. Coupled flow-geomechanics simulations are
computationally expensive and most of the computational time is usually
spent on geomechanics updates. We present a three-way coupling algorithm
for both single phase flow and compositional flow coupled with linear
poroelasticity. An error indicator is calculated at each flow time step
to determine when displacement must be updated and whether fixed-stress
iterative coupling technique is required. Convergence of the three-way
coupling is established by extending previous work on a priori analyses
of fixed-stress iterative coupling. Numerical results for Mandel’s
problem confirm these theoretical results for single phase flow.
Numerical results for coupled compositional flow and geomechanics
simulations for field-scale CO2sequestration and
surfactant-alternating-gas (SAG)-assisted CO2 sequestration achieve a
substantial reduction in mechanics update times for 99.4% and 97.5%,
respectively.