Speaker
Description
The large-scale deployment of Carbon Capture and Storage (CCS) is a critical pillar in global strategies to achieve net-zero emissions and mitigate climate change. However, the long-term viability of geological storage depends on the containment of CO2 within reservoir structures, requiring advanced technologies to ensure seal integrity and prevent buoyant migration through fractures or compromised wellbores. Colloidal silica gels are a promising adaptive solution, as they can be injected as low-viscosity fluids and triggered in situ to form stable barriers. However, their activation by CO2 rather than traditional chemical agents remains under-characterized regarding the dynamic parameters that govern deployment. This study presents an experimental characterization of colloidal silica gels activated exclusively by CO2, focusing on the fundamental link between time-dependent gas uptake and the resulting mechanical evolution.
The CO2 uptake kinetics were investigated across varying particle sizes and concentrations using high-precision pressure-decay measurements in closed isochoric systems. Application of real gas equations of state to the measured pressure and temperature profiles enabled the quantification of the cumulative moles of CO2 consumed by the suspension in real-time. These profiles were benchmarked against pure water baselines to isolate the excess CO2 demand associated specifically with colloidal destabilization and silanol buffering, distinguishing between simple physical dissolution and reaction-driven consumption, and quantifying the buffering capacity that dictates the time prior to the onset of gelation.
To link these chemical triggers to physical performance, rheometry was conducted within a high-pressure cell, tracking structural evolution under a constant CO2 pressure. We characterized the induction period, defined as the timeframe during which the fluid remains injectable, by monitoring viscosity as a function of CO2 exposure time under isobaric conditions. The sol-gel transition was identified through the crossover of storage (G’) and loss (G”) moduli, which are correlated with the molar uptake data to estimate the saturation level required for gel network formation. Dynamic frequency sweeps were used to characterize the final stiffness and viscoelastic damping of the mature gel to confirm mechanical integrity under sustained pressure. Complementing these bulk measurements, Scanning Electron Microscopy (SEM) provided qualitative insight into the morphology and particle connectivity of the formed gels.
Thus, this work provides a characterization of these sealing agents by prioritizing rate-dependent parameters over idealized equilibrium chemistry. The findings demonstrate the viability of CO2-responsive colloidal silica as an adaptive smart fluid that utilizes leaking or in-situ CO2 as its own activator, offering a robust foundation for enhancing the safety and efficiency of geological carbon storage in complex subsurface environments.
| Country | Saudi Arabia |
|---|---|
| Student Awards | I would like to submit this presentation into the Earth Energy Science (EES) and Capillarity Student Poster Awards. |
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