Enhanced recovery

Cellulose Nanocrystal Switchable Gel Improves CO2 Sweep Efficiency

This paper reveals the potential of an in-situ generated gel system designed with a bionanoparticle that has tunable strength and gelation reversibility in porous media for underground applications.

Reversibility of CNC hydrogel.
Fig. 1—Reversibility of CNC hydrogel. A CNC and imidazolium solution (left) when head space contains air, (middle) after sparging with CO2 (green tape applied to highlight gel surface), and (right) after sparging with N2.

The entanglement of biopolymers is a well-known phenomenon that, when controlled, can result in a smart fluid with strong gelation properties. The authors write that, when a suitable salt is incorporated into the cellulose nanocrystal (CNC), the fluids undergo gelation upon contact with bulk-phase carbon dioxide (CO2) but remain a flowing liquid otherwise. In this study, this composition-selective trigger was applied to improve sweep efficiency in CO2 enhanced oil recovery (EOR) and sequestration.


Hydrogels are hydrophilic structures that swell when hydrated and have various applications in industry. Hydrogels are of interest in EOR because of their ability to respond to stimuli such as pH, temperature, light, and ionic strength.

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