Perpustakaan Digital ITB

This study has a primary objective the evaluation of the effect of surface acidity of silica nanoparticles for mitigation of time-dependent thermal degradation of polymer solutions of partially hydrolyzed polyacrylamide (HPAM), for employment in chemical enhanced oil recovery (EOR) processes. For this, silica (SiO2) nanoparticles were modified on the surface with NaOH (SiO2B) and HCl (SiO2A). The obtained nanoparticles were characterized through field emission electron microscopy, surface area, total acidity by NH3-Temperature programmed desorption, dynamic light scattering (DLS), and electrophoretic light scattering (ELS) for zeta potential. The nanoparticle-polymer interaction was analyzed by adsorption isotherms. Also, the rheological behavior of HPAM solutions at 500 mg L?1 with and without 3000 mg L?1 of raw and functionalized nanoparticles was evaluated at a temperature of 70 °C through steady-state rheometry and dynamic oscillatory measurements at the day zero and after 15 days of aging. Also, coreflooding tests were carried out at conditions of pressure and temperature of a reservoir of interest using the aged polymer solutions with and without nanoparticles. The results show that the polymer adsorption decreases in the order SiO2B > SiO2>SiO2A, indicating that polymer uptake is higher as the surface acidity of nanoparticles decreases. SiO2B nanoparticles showed greater interactions between the functional groups on the surface and the HPAM in solution, forming a polymer network more resistant to degradation. A lower viscosity reduction with the addition of the unmodified SiO2 nanoparticles and SiO2B up to 49.6% and 22.9% was observed, respectively, and is closely related to the adsorption affinity and nanoparticles’ surface acidity. Coreflooding tests also indicated that, there is lower polymer retention in the porous medium when nanoparticles are included. In addition, the aged polymer solution with nanoparticles promotes an additional oil recovery of about 30% regarding polymer without nanoparticles.