The effects of pH, time and temperature on the stability and viscosity of cellulose nanocrystal (CNC) dispersions: implications for use in enhanced oil recovery

• Published in: Cellulose (London) Vol. 24; no. 10; pp. 4479 - 4491
• Main Authors: Molnes, Silje N., Paso, Kristofer G., Strand, Skule, Syverud, Kristin
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.10.2017; Springer Nature B.V
• Subjects: Additives; Bioorganic Chemistry; Cellulose; Cellulose derivatives; Cellulose nanocrystal (CNC); Ceramics; Chemical environment; Chemistry; Chemistry and Materials Science; CNC; Composites; Convergence of numerical methods; Dispersions; Enhanced oil recovery; Enhanced recovery; Glass; Heat; Heat aging; Ionization; Molecular biology; Nano-cellulose; Nanocellulose; Nanocrystals; Natural Materials; Oil recoveries; Oil recovery; Oil well flooding; Organic Chemistry; Original Paper; Petroleum reservoir engineering; Petroleum reservoirs; Physical Chemistry; Polymer Sciences; Reservoirs; Saline water; Stability; Stable dispersions; Studies; Sustainable Development; Temperature; Viscosity; Viscosity increase; Waterfronts; CNC; Nanocellulose; Temperature; Heat aging; Stability; Oil recovery
• ISSN: 0969-0239; 1572-882X; 1572-882X
• DOI: 10.1007/s10570-017-1437-0

Cellulose nanocrystals (CNC) are currently being investigated as potential additives for enhanced oil recovery (EOR). Presented in this paper is a study investigating the effects of different physical and chemical environments that low concentration CNC dispersions may be subjected to at oil reservoir conditions. Different concentrations of CNC dispersed in de-ionized water and in a 1000 ppm NaCl brine were subjected to variations in pH and temperature, and the results showed that the dispersions remained stable in the pH range expected in oil reservoirs (between 5 and 9). Stable dispersions were also observed when heated to temperatures ranging from 50 to 90 °C. At extended heat aging at 90 and 120 °C for seven days; beginning degradation was observed for both types of CNC dispersions; with viscosity increase and pH decrease as the most important indicators. CNC dispersed in 1000 ppm NaCl brine was generally more heat tolerant than the CNC dispersed in de-ionized water. The increase in viscosity during heat aging can be very interesting for EOR applications. A fluid that increases its viscosity with heat and time will be easier to inject due to a low initial viscosity, and when the viscosity increases in the porous reservoir, the effect can be a stable waterfront and less viscous fingering, which again can lead to increased sweep efficiency and better oil recovery.