Study on Mechanism of the Fracturing Fluid Performance Improvement and Oil Displacement Using Nanomaterials

To provide a theoretical basis for the development of functional fracturing fluids, SiO₂ was modified with C₈ and quaternary ammonium salt (QAS) on nanoscale (50 nm). The hydrophobic nanomaterial SiO₂-C₈ and hydrophobic charged nanomaterial SiO₂-QAS were synthesized. The compatibility, stability, and comprehensive performance of the SRFP polymer clean fracturing fluid systems were evaluated as nanomaterials SiO₂, SiO₂-C₈, and SiO₂-QAS were added. Quantitative simulation methods were employed to build the adsorption structure models and adsorption kinetics models of the nanomaterials on the sandstone surface. The adsorption and oil-water separation characteristics of nanomaterials on sandstone surfaces were analyzed. The experimental and simulation results show that the three nanomaterials, SiO₂, SiO₂-C₈, and SiO₂-QAS, display favorable dispersion stability in fracturing fluids. They can effectively reduce the surface and interfacial tension and demonstrate good temperature and shear resistance. SiO₂-C₈ and SiO₂-QAS nanomaterials are beneficial to the replacement of oil molecules on the sandstone surface and the oil-water separation when they are added into fracturing fluids. The addition of nanomaterials SiO₂-C₈ and SiO₂-QAS can also effectively improve the performance of fracturing fluids, enhance oil displacement, and reduce oil saturation within the spread range of fracturing fluids. The research results can provide a theoretical basis for the development of functional fracturing fluids and a reference for fracturing design optimization and fracturing fluid selection for tight oil and shale oil.