IMPROVING THE PERFORMANCE OF ZNO NANOPARTICLES FOR EOR IN HIGH-TEMPERATURE AND HIGH SALINITY CARBONATE RESERVOIRS

The main challenge of the application of nanofluids for enhanced oil recovery (EOR) in carbonate reservoirs is to maintain colloidal stability under reservoir conditions with high salinity and high temperature. In this study, we address this issue by increasing the stability and hydrophilicity of ZnO nanoparticles by adding TTIP. Adding TTIP on the surface of ZnO nanoparticles results in an increase in the hydrophilic heads in the final product. Then, these nanoparticles are used to coat carbonate rock surfaces to change their wettability. The coated rock plates are obtained by aging them in nanofluids. The modified ZnO-based coatings show to be more effective for wettability alteration purposes compared to the conventional ZnO coating. The un-coated rock plate is strongly oil-wet, where the water and n-heptane droplets contact angles on this surface are 168 degrees and 0 degrees, respectively. After aging the rock samples in nanofluids, superhydrophilic coatings form on the superhydrophobic surfaces. The rock surface before and after treatment, as well as the synthesized nanoparticles, are characterized by scanning electron microscope (SEM), x-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR) analyses. Results of this study indicate the possibility of using the materials for wettability alteration of oil-wet carbonate rock in the EOR process. The results of core flooding tests demonstrate that the oil recovery enhances significantly through the nanofluid flooding.