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

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 degrees C. Spectral characterization, the rheological properties, adsorption characteristics, and oil recovery efficiency from modeled 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.

Automated summary

This study investigates the potential of CO2-triggered and thermo-responsive gel as a plugging agent for heterogeneous sandstone formations, examining its spectral characteristics, rheological properties, adsorption characteristics, and oil recovery efficiency. Results show that the partition of hydrolyzed monomers during polymerization is controlled by CO2 bubbling during gel preparation, while gelation time and rheological properties depend on formation temperature and the presence of salts, with calcium and sulfate salts having the most significant effect. Oil recovery is influenced by permeability distribution and polymer adsorption mitigation, with CO2-triggered gels proving effective in formations with contrasted permeability but less so in homogeneous formations.