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Cellulose Nanocrystal-Polyelectrolyte Hybrids for Bentonite Water-Based Drilling Fluids
Paul Balding1,2, Mei-Chun Li3, Qinglin Wu3
1School of Chemistry & Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332, United States.
ACS Applied Bio Materials
|January 13, 2022
Summary
Modified cellulose nanocrystals (CNCs) with polyelectrolytes (PEs) improve drilling fluid filtration performance in high salt conditions. Grafted CNC-PE hybrids prevent bentonite aggregation, enhancing fluid retention for effective well excavation.
Area of Science:
- Materials Science
- Colloid and Surface Chemistry
- Petroleum Engineering
Background:
- Cellulose nanocrystals (CNCs) enhance bentonite-based drilling fluid (BT-WDF) filtration.
- High salt concentrations degrade BT-WDF performance by reducing CNC-BT interactions and causing bentonite aggregation.
- Novel hybrid materials are needed to maintain BT-WDF stability and performance in saline environments.
Purpose of the Study:
- To develop and evaluate polyelectrolyte-grafted cellulose nanocrystals (CNC-PEs) for improved BT-WDF filtration performance in high salt.
- To investigate the effect of different grafting methods and polyelectrolyte types on CNC-PE interactions with bentonite platelets.
- To understand the mechanisms of steric and electrostatic stabilization provided by CNC-PEs in preventing bentonite aggregation.
Main Methods:
- Grafting polyelectrolytes (PSS, PAM, PSS-co-PAM) onto CNCs using direct surface initiation and GMA modification.
- Physical mixing of CNCs and polyelectrolytes as a control.
- Incorporation of CNC-PEs into bentonite-water-based drilling fluids (BT-WDFs).
- Evaluation of fluid filtration performance under high salt concentrations.
Main Results:
- Covalently grafted CNC-PEs significantly improved filtration properties compared to physically mixed counterparts.
- Direct grafting yielded better results than GMA modification due to reduced interparticle cross-linking.
- Anionic PSS-modified CNC-PEs attached to bentonite edges, while cationic PAM-modified CNC-PEs attached to bentonite faces.
- The PSS-co-PAM CNC hybrid demonstrated the most effective disruption of bentonite aggregation and superior filtration.
Conclusions:
- Grafting polyelectrolytes onto CNCs is an effective strategy to create stable BT-WDFs for high-salinity conditions.
- Steric and electrostatic stabilization by CNC-PEs prevents bentonite aggregation, crucial for maintaining filtration performance.
- The PSS-co-PAM CNC hybrid offers a promising solution for high-performance drilling fluids in challenging environments.
