Evaluation of CO2-triggered and thermo-responsive gels for heterogeneous oil formations

Abstract

ABSTRACT Herein is investigated the potential of CO2-triggered and thermo-responsive gel as plugging agent for heterogeneous sandstone formations. The gel starts to swell from a silica-based nanofluid solution at a temperature as high as 55\xa0oC. Spectral characterization, the rheological properties, adsorption characteristics, and oil recovery efficiency from modelled heterogeneous formations are studied. The spectral characterization revealed that CO2 bubbling during gel preparation controls the partition of hydrolyzed monomers during the polymerization by silica nanoparticles. The gelation time and the gel rheological properties depend both on the formation temperature, the presence in salts. For either parameter investigated, calcium and sulfate salts have the most prominent effect. The oil recovery depends not only on the permeability distribution but also on the mitigation of the polymer adsorption. The application of CO2-triggered gels could be effective in formation with contrasted permeability but fails to give promising results for homogeneous formations.