Rheological properties and gas channeling plugging ability in CO2 flooding of a hydrophobic nanoparticle-enhanced smart gel system constructed with wormlike micelles

Abstract

Carbon Dioxide capture, oil displacement and Storage (CCUS-EOR) projects inject captured carbon dioxide into developed reservoirs suitable for gas displacement. However, due to the strong heterogeneity of the reservoir, the CO2 channeling is seriously. In this study, using tung oil as renewable chemical raw material, environmentally friendly surfactants and hydrophobic nano-SiO2 were synthesized as the main components of smart gel system. Fourier transform infrared (FT-IR), nuclear magnetic resonance spectrum (NMR) and thermogravimetric analysis (TGA) were used to characterize the chemical structure. The smart gel system was obtained through the CO2 response experiment. The system can cycle back and forth between low and high viscosity multiple times, and a good temperature resistance and salt resistance. The results of rheological experiments and dynamic light scattering show that the nanoparticles promote the growth and entanglement of WLMs. The plugging capacity and auxiliary CO2-EOR performance of the system were evaluated through the laboratory displacement test. The intelligent response system has good gas channeling plugging ability, plugging efficiency reaches 97 %, and CO2 flooding oil recovery efficiency increases by 22.2 %. In addition, in the acute toxicity assessment, the bio-based gel system from plants showed slightly toxic, which is expected to become a new generation of green oilfield chemicals.