Using Direct Numerical Simulation of Pore-Level Events to Improve Pore-Network Models for Prediction of Residual Trapping of CO2

Journal Article · 04 January 2022 · Frontiers in Water

DOI: https://doi.org/10.3389/frwa.2021.710160 · OSTI ID:1838229

Kohanpur, Amir H.; Chen, Yu; Valocchi, Albert J.

Direct numerical simulation and pore-network modeling are common approaches to study the physics of two-phase flow through natural rocks. For assessment of the long-term performance of geological sequestration of CO ₂ , it is important to model the full drainage-imbibition cycle to provide an accurate estimate of the trapped CO ₂ . While direct numerical simulation using pore geometry from micro-CT rock images accurately models two-phase flow physics, it is computationally prohibitive for large rock volumes. On the other hand, pore-network modeling on networks extracted from micro-CT rock images is computationally efficient but utilizes simplified physics in idealized geometric pore elements. This study uses the lattice-Boltzmann method for direct numerical simulation of CO ₂ -brine flow in idealized pore elements to develop a new set of pore-level flow models for the pore-body filling and snap-off events in pore-network modeling of imbibition. Lattice-Boltzmann simulations are conducted on typical idealized pore-network configurations, and the interface evolution and local capillary pressure are evaluated to develop modified equations of local threshold capillary pressure of pore elements as a function of shape factor and other geometrical parameters. The modified equations are then incorporated into a quasi-static pore-network flow solver. The modified model is applied on extracted pore-network of sandstone samples, and saturation of residual trapped CO ₂ is computed for a drainage-imbibition cycle. The modified model yields different statistics of pore-level events compared with the original model; in particular, the occurrence of snap-off in pore-throats is reduced resulting in a more frontal displacement pattern along the main injection direction. Compared to the original model, the modified model is in closer agreement with the residual trapped CO ₂ obtained from core flow experiments and direct numerical simulation.

• Sponsoring Organization: USDOE
• OSTI ID: 1838229
• Journal Information: Frontiers in Water, Journal Name: Frontiers in Water Vol. 3; ISSN 2624-9375
• Publisher: Frontiers Media SACopyright Statement
• Country of Publication: Switzerland
• Language: English