09:15 〜 09:30
[HSC07-02] Numerical Simulation of the Experimentally Observed Poroelastic Behavior of Sandstone in the Two-Phase Fluid System of Water and CO2
キーワード：二酸化炭素地中貯留、コア流動試験、多孔質弾性、モニタリング、二相流、数値シミュレーション
Ensuring effectiveness and safety is paramount for successfully implementing CO2 geological storage. A prior forecast and risk management of the subsurface dynamics are required to ensure secure storage. So monitoring is necessary during the injection and post-injection. The monitoring technology for CO2 geological storage aims to ascertain the extent of the CO2 plume and the spatial impact of the pressure perturbation resulting from the CO2 injection. The poroelastic characteristics of rock play a crucial role in the holistic assessment of safety measures for the geological storage of CO2. The strains induced by fluid injection in porous media may lead to reservoir deformation, influence wellbore stability, and even endanger storage security. Therefore, a thorough understanding of poroelastic behavior is essential to ensuring the secure and efficient sequestration of CO2 in subsurface reservoirs.
To confirm poroelastic behavior during fluid injection, we conducted core flooding experiments to examine the behavior of Berea sandstone during fluid flow. X-ray CT measured the evolution of the CO2 distribution. The change in strain due to core deformation can be probed by fiber-optic distributed strain sensing attached around the core sample. This experiment observed a clear difference between single-phase (water) and two-phase (water and CO2) injections. In the case of the single-phase fluid core flood, the changes in strain gradually decrease and become a steep slope following Darcy’s law over the core sample length, whereas, in the case of the two-phase fluid core flood, the strain has a gentler decrease, with almost no fluctuation over a long-distance. This difference is considered a poroelastic effect of rock in the two-phase fluid system. In comparing the results of coupled hydromechanical simulations for single-phase (water) and two-phase (water and CO2) flow, we observed CO2 saturation, pressure, strain, etc., and evaluated the simulation results by comparing them with the experimental results qualitatively.
Numerical simulation coupling the two-phase fluid flow of CO2 and water and poroelastic deformation was performed to understand the experimental results. We modeled the fluid injection into a cylindrical sandstone specimen, where the rock is considered a poroelastic medium. To perform the simulations, a finite-element mesh with two-dimensional axial symmetry was created. The rock model consists of solid components with constant porosity and permeability. The CODE_BRIGHT simulator was used for numerical simulations. The simulation results show that, firstly, it was noted that the amount of strain generated in the rock sample was approximately similar between the single-phase and two-phase flow scenarios. This suggests that the magnitude of the mechanical response of the rock to fluid injection is consistent regardless of the presence of CO2. Furthermore, the observed experimental results could be reproduced in the numerical simulation. The distribution of strain along the length of the core sample did not become a steep slope between the core ends during the two-phase flow; the strain decreased gradually, with essentially no variation over long distances. The simulation shows a good capture of the main trends in strain behavior for the core flood experiment. The strain distribution highlights the complex nature of fluid-rock interactions during CO2 injection and underscores the importance of considering local variations in pore fluid distribution and mechanical properties when simulating such processes.
These findings contribute to a deeper understanding of the poroelastic behavior of rocks during CO2 injection, which is essential for predicting subsurface responses and ensuring the safe and effective implementation of CO2 storage technologies. This work could shed light on the mechanism of poroelastic behavior induced by CO2 injection in saline aquifers.
To confirm poroelastic behavior during fluid injection, we conducted core flooding experiments to examine the behavior of Berea sandstone during fluid flow. X-ray CT measured the evolution of the CO2 distribution. The change in strain due to core deformation can be probed by fiber-optic distributed strain sensing attached around the core sample. This experiment observed a clear difference between single-phase (water) and two-phase (water and CO2) injections. In the case of the single-phase fluid core flood, the changes in strain gradually decrease and become a steep slope following Darcy’s law over the core sample length, whereas, in the case of the two-phase fluid core flood, the strain has a gentler decrease, with almost no fluctuation over a long-distance. This difference is considered a poroelastic effect of rock in the two-phase fluid system. In comparing the results of coupled hydromechanical simulations for single-phase (water) and two-phase (water and CO2) flow, we observed CO2 saturation, pressure, strain, etc., and evaluated the simulation results by comparing them with the experimental results qualitatively.
Numerical simulation coupling the two-phase fluid flow of CO2 and water and poroelastic deformation was performed to understand the experimental results. We modeled the fluid injection into a cylindrical sandstone specimen, where the rock is considered a poroelastic medium. To perform the simulations, a finite-element mesh with two-dimensional axial symmetry was created. The rock model consists of solid components with constant porosity and permeability. The CODE_BRIGHT simulator was used for numerical simulations. The simulation results show that, firstly, it was noted that the amount of strain generated in the rock sample was approximately similar between the single-phase and two-phase flow scenarios. This suggests that the magnitude of the mechanical response of the rock to fluid injection is consistent regardless of the presence of CO2. Furthermore, the observed experimental results could be reproduced in the numerical simulation. The distribution of strain along the length of the core sample did not become a steep slope between the core ends during the two-phase flow; the strain decreased gradually, with essentially no variation over long distances. The simulation shows a good capture of the main trends in strain behavior for the core flood experiment. The strain distribution highlights the complex nature of fluid-rock interactions during CO2 injection and underscores the importance of considering local variations in pore fluid distribution and mechanical properties when simulating such processes.
These findings contribute to a deeper understanding of the poroelastic behavior of rocks during CO2 injection, which is essential for predicting subsurface responses and ensuring the safe and effective implementation of CO2 storage technologies. This work could shed light on the mechanism of poroelastic behavior induced by CO2 injection in saline aquifers.