Preparation of super-hydrophobic nano-silica aqueous dispersion and study of its application for water resistance reduction at low-permeability reservoir

The preparation of a super-hydrophobic nano-silica and its surface-modification by surfactant using the in situ modification has been discussed. As-prepared super-hydrophobic nano-silica can be well dispersed in water to form a transparent aqueous dispersion with primary particle size and narrow particle size distribution. Core displacement tests simulated at the laboratory show that the as-prepared aqueous dispersion of nano-silica is able to significantly improve water phase permeability and pressure difference. Also the super-hydrophobic nano-silica can be well adsorbed on porous core walls to transform the hydrophilicity into super-hydrophobicity with contact angle > 150 degrees by combining surface roughening with surface chemical modification, showing great potential for reducing flow resistance and enhancing water injection at low-permeability reservoirs.