A parallel compositional reservoir simulator for large-scale CO₂ geological storage modeling and assessment

Area of Science:

• Geological Engineering
• Computational Science
• Environmental Science

Background:

• Carbon capture and storage (CCS) is vital for carbon neutrality.
• Simulating CO2 storage in deep aquifers and depleted reservoirs is complex due to multi-component gas-brine systems.
• Existing simulators lack the capacity to model diverse gas species relevant to evolving CCS scenarios.

Purpose of the Study:

• To develop a robust, scalable, and parallelized simulator for CO2 geological storage.
• To enhance the compositional fluid model to accommodate a wider range of gas species, including H2 and O2.
• To accelerate phase equilibrium calculations using an improved stability analysis bypassing (SAB) method.

Main Methods:

• Developed a three-dimensional fully implicit parallel CO2 geological storage simulator (PRSI-CGCS) on distributed-memory computers.
• Implemented a compositional fluid model supporting CO2, C1-C3, N2, H2S, H2, and O2.
• Optimized the SAB method with modified scaling factors for gas-brine phase equilibrium calculations.

Main Results:

• PRSI-CGCS demonstrates scalability and robustness for large-scale CO2 storage simulations.
• The modified SAB method reduced stability analyses by 61.39% to 88.71%, significantly cutting simulation time.
• Case studies showed H2 and O2 impurities reduce CO2 storage capacity and increase injection pressure, though impact is minor below 10% impurity.

Conclusions:

• PRSI-CGCS is a validated tool for complex CO2 geological storage simulations.
• The enhanced simulator and SAB method improve computational efficiency and accuracy.
• Presence of H2 and O2 as impurities can negatively affect CO2 storage performance, necessitating careful monitoring.