Predicting gelation kinetics of colloidal silica for water shut-off treatments: A novel Arrhenius-based model

This work presents a novel model, developed from extensive laboratory measurements, to predict the gelation kinetics of colloidal silica gel systems for water conformance applications, targeting water shut-off treatment with a silica-based nanofluid system. These nanofluids leverage colloidal silica dispersions, which, with their high silica content and low viscosity, allow for deeper penetration within targeted reservoir zones, leading to a more effective water shut-off treatment. Extensive measurements were conducted to investigate the gelation process of this precursor solution activated with sodium silicate under various conditions, including activator concentration, temperature, dilution, metal ion presence, and shear rate. A key parameter, High Viscosity Threshold Time (HVTT), was introduced to represent the critical time at which a colloidal silica gel system undergoes a rapid increase in viscosity, transitioning from a fluid-like to a solid-like state. This parameter is essential for understanding and controlling the gelation process in water shut-off treatments, as it indicates the onset of significant gel network formation that restricts fluid flow within high-permeability zones of a reservoir. HVTT is influenced by various factors, including activator concentration, temperature, water dilution, and shear rate, and can be predicted using an Arrhenius-based model developed in this study. The analysis demonstrates that gelation follows an Arrhenius-type relationship at different temperatures. Building upon this, an extended Arrhenius equation incorporating activator concentration and dilution is developed. This equation allows for predicting HVTT. This model has the potential to be integrated into reservoir simulators, aiding in the optimization of conformance control strategies. This approach shows significant promise for expanding the application of silicate gel systems in conformance control.