Analyzing the impact of across-fault flow in carbon geological storage: A simulation study

Abstract

Carbon geological storage (CGS) aims to mitigate climate change by sequestering carbon dioxide in underground formations. The simulation study plays a crucial role during the EPA Class VI permit application process in defining the area of review (AOR). Boundary conditions play a significant role in delineating the AOR and specifically faults (as a boundary condition) and how they are modeled poses a considerable challenge to accurately model CO₂ storage and containment. Addressing this challenge is vital to understanding how faults impact storage processes and pressure build-up in the formation. This study identifies the gap between geological modeling and dynamic simulations, particularly concerning fault representation in numerical simulation models. We selected a field model with typical geological formation features of the onshore Gulf of Mexico Basin, including multiple faults. Two options were leveraged: fault transmissibility multiplier (TM), and Across-fault pressure difference (AFPD) for fluid flow. We considered various scenarios of these options’ in containing CO₂ and brine multiphase flow and assessed the containment of CO₂ and evolution of the AOR and the dynamic pressure build-up. This study not only provides lessons on how to better model fault boundary conditions, but also on how our modeling assumptions related to faults would impact flow behaviors and AOR.