Numerical Model for Colloidal Silica Injected Column Tests

Abstract

The UTCHEM flood simulator was used to develop a numerical model to simulate colloidal silica transport through sand columns. Most existing numerical models for colloidal silica modeling include the gelation process, in which the viscosity gradually becomes orders of magnitude greater than the initial grout viscosity. However, in field grouting applications of shallow, loose, cohesionless deposits, injection at high viscosities may be limited due to allowable pressure limitations. In these cases, the injection is planned to be completed just before the gelling reaction begins. Thus, modeling the gelation process may not be necessary. The UTCHEM simulator accounts for fluids with varying densities and viscosities, making it a useful tool for simulating colloidal silica injection in cases where gelation does not need to be modeled explicitly. The model was validated using laboratory data from five column tests in which loose sand was treated with colloidal silica grout and one column test in which sand was treated with sodium silicate. The numerical model accurately represented the physical experiments. The numerical model provides a validated tool that can be used to design and optimize stabilizer delivery for laboratory and field applications in which gelation does not need to be modeled explicitly.