Temperature stability of nanocellulose dispersions

Area of Science:

• Materials Science
• Chemical Engineering
• Petroleum Engineering

Background:

• Cellulose nanofibrils (CNF) are explored as rheology modifiers for water-based fluids.
• Applications include drilling fluids and enhanced oil recovery (EOR) injection water.
• Harsh downhole conditions (high temperature, long retention time) necessitate evaluating nanocellulose stability.

Purpose of the Study:

• To assess the temperature stability of nanocellulose dispersions under simulated oil well conditions.
• To determine the suitability of CNF and cellulose nanocrystals (CNC) as rheology modifiers in high-temperature environments.
• To evaluate the impact of additives on nanocellulose dispersion stability.

Main Methods:

• Heat aging of CNF dispersions produced via mechanical, TEMPO-mediated oxidation, and carboxymethylation methods.
• Heat aging of cellulose nanocrystals (CNC) dispersions.
• Evaluation of temperature stability after exposure to elevated temperatures for extended periods.
• Assessment of the effect of additives (cesium formate, sodium formate, phosphate buffer) on dispersion stability.

Main Results:

• Cellulose nanocrystals (CNC) exhibited the best temperature stability.
• Mechanically produced CNF dispersions were stable after heating to 140°C for three days.
• Cesium formate and sodium formate significantly increased the temperature stability of the dispersions.
• Phosphate buffer showed no effect on dispersion stability.

Conclusions:

• Nanocellulose, particularly CNC and mechanically produced CNF, shows potential for use in high-temperature rheology modification.
• Additives like cesium formate can enhance the thermal stability of nanocellulose dispersions for demanding applications.
• Further research is warranted to optimize nanocellulose formulations for extreme downhole environments.