Electrokinetic Stabilization of Formation Fines Using Surface Modified Polymer Silica Nanocomposites During Low Salinity Water Flooding for Enhanced Oil Recovery

ABSTRACT Fines migration induced by low salinity water flooding severely impairs reservoir permeability and injectivity presenting a critical challenge in enhanced oil recovery. This study aims to synthesize and evaluate a surface‐modified polymer‐silica nanocomposite to mitigate clay mobilization and preserve the hydrodynamic capacity of porous media. A layer‐by‐layer electrostatic self‐assembly methodology was employed to graft cetyltrimethylammonium bromide and poly diallyl dimethylammonium chloride onto silica nanoparticles. The structural and electrokinetic properties were characterized using dynamic light scattering and zeta potential measurements, whereas particle interaction mechanisms were evaluated through Derjaguin‐Landau‐Verwey‐Overbeek (DLVO) theoretical modeling. Subsequently, high‐pressure, high‐temperature core flooding experiments were conducted on clay‐rich sandstone plugs to monitor dynamic permeability alterations. Results indicated that the functionalized nanocomposite exhibited optimal colloidal stability at a concentration of 1000 ppm. Furthermore, DLVO modeling and empirical electrokinetic data revealed that the cationic nanoparticles successfully neutralized the highly negative surface charges of kaolinite clays, preventing the expansion of the electrical double layer and recreating a dominant attractive van der Waals energy regime. Core flooding confirmed that although pure low salinity water reduced absolute permeability by over 98%, the injected nanofluid retained over 80% of the initial rock permeability by preventing pore throat bridging. In conclusion, the engineered nanocomposite provides a robust thermodynamic and mechanical mechanism for anchoring in situ fines, offering a highly effective chemical intervention to sustain well injectivity during low salinity water flooding.