Role of fracture aperture in cement self-healing under carbonated brine flow

• Examined self-sealing/Opening of cement fracture using reactive transport model. • Different sealing time of 1D compared to the equivalent 2D. • 2D heterogeneous cases stayed sealed under high pressure gradient, while 1D open. • Revised seal/open diagram for complex self-affined 2D fracture. • 1D transition quickly from self-seal to non-seal, whereas 2D transition more slowly. • Sample 2 with higher heterogeneity showed higher self-sealing capacity. This study investigates the self-healing and opening behavior of fractured cement sheaths exposed to reactive advective carbonated brine flow, with emphasis on the role of fracture aperture variability. Maintaining cement sheath integrity is critical for subsurface applications such as CO 2 storage and hydrocarbon production. Previous studies mainly addressed fractures with constant apertures or one-dimensional variable aperture models, offering limited guidelines for self-healing. Here, we apply advanced reactive transport modeling to capture the influence of heterogeneous, rough-walled fractures on healing capacity. Our results show that one-dimensional simulations underestimate the complexity of coupled flow, reaction, and hydromechanical processes, leading to conservative predictions of fracture sealing. In contrast, two-dimensional heterogeneous models reveal enhanced self-healing mechanisms arising from aperture variability. Based on these findings, we propose a revised sealing/opening diagram that incorporates the role of fracture roughness and heterogeneity. This work provides new insights into cement fracture behavior under reactive flow and highlights the necessity of upscaling fracture geometry effects when evaluating long-term wellbore integrity.