Impact of Geomechanical Heterogeneity on the Mobilized Friction Coeffcient

Underground green hydrogen storage is a key technology for achieving net-zero carbon goals. However, injecting gas into the subsurface introduces anthropogenic stresses that may destabilize faults, leading to sliding and safety risks. Traditional risk assessments rely on deterministic models that often overlook critical stress zones caused by variability in mechanical properties. To address this, we developed a 2D numerical model to evaluate the effects of heterogeneity on fault stability using stochastic analysis. Two stress regimes—normal faulting and strike-slip—were studied. Random Gaussian fields of Young’s modulus introduced variability, allowing us to examine the influence of standard deviation, correlation length, and stratification angle. Our results show that heterogeneity reduces the safe pressure threshold, increasing fault reactivation risk. Variability in mechanical properties, particularly standard deviation, plays a greater role in stability than geometric arrangements. This study advocates for replacing deterministic approaches with statistical analyses that quantify sliding probabilities, offering a more reliable framework for assessing subsurface risks.