[H-SC05] CCUS (Carbon Dioxide Capture, Utilization, and Storage) for Climate Mitigation

[HSC05-09] Numerical Simulation of Geophysical Changes based upon CO₂ Geological Storage and Leakage

*Yuki Kano^1,2, Tsuneo Ishido^1,2 (1.Geological Carbon Dioxide Storage Technology Research Association, 2.National Institute of Advanced Industrial Science and Technology)

Keywords:CO2 geological Storage, CO2 Leakage, Numerical simulation, Geophysical monitoring

For the monitoring of Carbon Capture and Storage (CCS), a variety of geophysical data will be useful to perceive the behavior of injected CO₂ and to detect a leakage if occurs. Since required monitoring period will be substantially long, cost-effective monitoring methods are desirable. To design such monitoring plan, it is necessary to predict whether and where observable changes will appear due to CO₂ migration in a quantitative way.
In this presentation, we will report the results of numerical simulations of changes in geophysical observables based upon hypothetical CO₂ geological storage and leakage calculations. Calculated geophysical data includes seismic reflection, microgravity and seafloor surface displacement. The results indicate that the location of observable changes and detection possibility of a leakage in early stages.
A 3D model was built representing an inshore saline aquifer below the seabed of 20-m water depth. A high-permeable sandstone layer located at about 1 km below the seabed is considered to be the reservoir. A low-permeable seal layer is overlaid by a secondary aquifer and seal, and a top Quaternary sediment. CO₂ is injected into the reservoir at a rate of 0.4 Mt/year for 50 years. Numerical simulations of the injection period and following shut-in period were carried out for a no leakage case and a few cases where a leakage took place. A hypothetical fault was supposed to be the leakage path and assumed to open at the end of the injection. Fluid flow simulations were carried out using the "STAR" reservoir simulation code (Pritchett, 1995; Pritchett, 2002) with the "SQSCO2" equations of state package (Pritchett, 2008), and then geophysical data was calculated using STAR’s "Geophysical Postprocessor" (Pritchett, 2003; Ishido et al., 2011; Ishido et al., 2015).
This presentation is based on results obtained from a project (JPNP18006) commissioned by the New Energy and Industrial Technology Development Organization (NEDO) and the Ministry of Economy, Trade and Industry (METI) of Japan.

References
Ishido, T., Tosha, T., Akasaka, C., Nishi, Y., Sugihara, M., Kano, Y. and Nakanishi, S. (2011): Changes in geophysical observables caused by CO₂ injection into saline aquifers. Energy Procedia 4, 3276-3283.
Ishido, T., Pritchett, J.W., Nishi, Y., Sugihara, M., Garg, S.K., Stevens, J.L., Tosha, T., Nakanishi, S., Nakao, S. (2015): Application of Various Geophysical Techniques to Reservoir Monitoring and Modeling. Proc. World Geothermal Congress, Melbourne, Australia, 19-25 April 2015.
Pritchett, J.W. (1995): STAR-a geothermal reservoir simulation system. Proc. World Geothermal Congress, Florence, 853-858.
Pritchett, J.W. (2002): STAR User’s Manual Version 9.0, SAIC Report Number 02/1055
Pritchett, J.W. (2003): Verification and Validation Calculations Using the STAR Geophysical Postprocessor Suite. SAIC Report Number 03/1040; 2003.
Pritchett, J.W. (2008): New "SQSCO2" equation of state for the "STAR" code, SAIC