Numerical Simulation of Long-Term Fate of CO₂ Stored in Deep Reservoir Rocks on Massively Parallel Vector Supercomputer

Abstract

As one of the promising approaches for reducing greenhouse-gas content in the atmosphere, CCS (carbon dioxide capture and storage) has been recognized worldwide. CO₂ is captured from large emission sources and injected and stored in deep reservoir rocks, including saline aquifers, depleted oil and gas field. Under typical pressure and temperature conditions at deep reservoirs (depths > 800m), CO₂ will be stored in supercritical state, subsequently dissolving in groundwater, and eventually forming carbonate minerals through geochemical reactions in a long-term (e.g., thousands of years). To ensure the safety and permanence of the storage, numerical simulation is considered as the most powerful approach for predicting the long-term fate of CO₂ in reservoirs. A parallelized general-purpose hydrodynamics code TOUGH2-MP has been used on scalar architectures where it exhibits excellent performance and scalability. However, on the Earth Simulator (ES2), which is a massively parallel vector computer, extensive tune-ups were required for increasing the vector operation ratio. In this paper, the performance of the modified TOUGH2-MP code on ES2 is presented with some illustrative numerical simulations of long-term fate of CO₂ stored in reservoirs.