Characterization of Fault Gouge Material Behavior under CO₂ Storage Conditions

Abstract

Fault zones play a critical role in the integrity of geological CO2 storage systems, where fault gouge material is an essential element in controlling fluid flow and the mechanical properties of the caprock-reservoir system. However, the hydro-mechanical properties of fault gouge and their impact under CO2 storage conditions still need to be better understood, threatening leakage risk. The objective of this research is to better understand fault gouge properties and their effects on caprock integrity, using both experimental and modeling approaches. The permeability and mechanical behavior are examined in coreflooding, uniaxial, and direct shear tests. The findings are incorporated into a hydro-mechanical numerical model to simulate fault behaviour and leakage risk. It is found that permeability and mechanical properties are significantly influenced by clay content and confining pressure, revealing the interactions between sealing and mechanical properties. The findings enhance understanding of fault gouge properties and help inform a more accurate approach to CO2 storage design and risk analysis.