A5-a3 - Numerical Analysis of Wave Propagation in Partially Saturated Porous Formations for CO2 Geological Sequestration
- Event
- 2025 ICU PADERBORN - 9th International Congress on Ultrasonics
2025-09-21 - 2025-09-25
Paderborn - Band
- Lectures
- Chapter
- A5-a - Computational Acoustics for Complex Media and Structures
- Author(s)
- X. Zhang, Y. Qi, L. Liu - Chinese Academy of Sciences, Beijing (China)
- Pages
- 53 - 56
- DOI
- 10.5162/Ultrasonic2025/A5-a3
- ISBN
- 978-3-910600-08-9
- Price
- free
Abstract
Understanding elastic wave propagation in unsaturated porous media, critical for geophysical exploration, especially in hydrocarbon reservoirs and CO2 storage formations, demands accurate numerical frameworks. This study introduces a numerical model based on Lo’s three-phase theory to analyze wave dynamics in two-fluid saturated porous media. The governing equations are reformulated into a velocity-stress form and solved using a hybrid algorithm that combines the time-splitting scheme and staggered-grid finite-difference method (FDM), effectively addressing stiffness issues in porous media simulations. Our findings reveal four distinct wave modes: three compressional waves (P1, P2, P3) and one shear wave (S). Notably, slow compressional waves (P2, P3), driven by solid-fluid and fluid-fluid relative motions, show strong dependence on fluid viscosity and frequency. Although these waves are rarely observable at seismic frequencies, their energy distribution and conversion into propagating P1/S waves at interfaces are crucial. Wavefield snapshots demonstrate complex mode conversions among all four waves, reflecting intricate solid-wetting/nonwetting fluid coupling. Key contributions include the algorithm’s robustness in simulating multi-wave phenomena, the fluid-phase energy dominance in slow waves, and the complexity of interface-induced mode conversions.