Partially hydrolyzed polyacrylamide apparent viscosity in porous media enhancement by silica dioxide nanoparticles under high temperature and high salinity

Abstract

Polymer flooding effectiveness is hindered by high temperature and high salinity due to polymer degradation. Researchers proposed the addition of nanoparticles to improve polymer stability to withstand reservoir conditions. Therefore, extensive rheological study and flooding test of partially hydrolyzed polyacrylamide (HPAM) solutions with silica dioxide nanoparticles (SiO2 NPs) were carried out under high temperature and high salinity conditions. The shear viscosity of HPAM-SiO2 NPs in the rheological study was measured using a rheometer while apparent viscosity in porous media was calculated from flooding test and modelled using a numerical model. Apparent viscosity includes shear viscosity and elongational viscosity. Shear viscosity was estimated from the Carreau-Yasuda model and elongational viscosity was correlated with Deborah number via relaxation time. At T=80°C the shear viscosity and apparent viscosity in porous media of HPAM-SiO2 NPs are 50% and 64% higher than HPAM. The results further show that HPAM-SiO2 NPs’ shear viscosity and apparent viscosity in porous media at 60,000 ppm of NaCl are 39% and 53% higher than HPAM, respectively. Nevertheless, the enhanced apparent viscosity of HPAM-SiO2 NPs was owed to the formation of stable and dense interwoven HPAM molecules induced from the hydrogen bonds and alkoxysilane (Si-O-Si) crosslinks between SiO2 NPs and HPAM. This study suggested that the addition of SiO2 NPs could significantly improve the HPAM apparent viscosity in porous media under high temperature and high salinity producing an ideal mobility control agent.

Keywords

• shear viscosity
• apparent viscosity
• porous medium
• viscoelastic
• carreau-yasuda model
• deborah number