Nanoparticles-assisted surface charge modification of the porous medium to treat colloidal particles migration induced by low salinity water flooding

摘要

In this experimental study, nanoparticles (NPs) treatment of low salinity water (LSW) flooding in order to mitigate the induced colloidal particles migration in the medium has been investigated. Two sets of coreflood experiments were conducted. In the first set, engineered cores were utilized as porous media. In these experiments five types of metal oxide nanoparticles, γ-Al_2O_3, CuO, MgO, SiO_2, and ZnO, were utilized to treat the medium. In twelve flooding tests, LSW was injected into the already NP-treated core and the effluent's particle concentration was analyzed using a turbidimeter apparatus. These experiments were conducted to find the best NP as an adsorbent of tiny particles. In the second set of the experiments, coreflood tests were performed using Berea cores to investigate the NP treatment of permeability impairment induced by LSW flooding. Quantification methods of dynamic light scattering and zeta potential analysis were done to compare different scenarios. It was found that soaking the medium with a nanofluid slug prior to LSW flooding can be a very promising remedy for the formation damage subsequently induced. The surface charge of the medium treated by γ-Al_2O_3 NP increases to a critically high value of 33.2mV which in turn, results in a 70% reduction of fines migration compared with the blank test. In addition, the ionic strength of the nanofluid was recognized as an important parameter that affects the treatment efficiency. It was also found that when nanoparticles disperse better in solution they have greater tendencies to alter the surface properties of the medium. The calculated total surface forces quantitatively confirmed the experimental results. Furthermore, the results confirmed that the severe permeability impairment induced by LSW flooding can be dramatically remedied due to the effect of γ-Al_2O_3 NP.