Modified cellulose nanocrystals and their use in drilling fluids
AssigneeBoard of Supervisors of Louisiana State University and Agricultural and Mechanical College
InventorsQinglin Wu, Meichun Li
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Abstract
Bentonite (or other clay) water-based drilling fluids incorporating functionalized cellulose nanocrystals are disclosed. Cellulose nanocrystals are modified with tailored surface charges or tailored levels of salt-tolerant polymer grafting, and combined with bentonite (or other clay) nanoplatelets in an aqueous suspension. Thermal performance of drilling fluids can also be enhanced by surface grafting of thermally functional polymers onto cellulose nanocrystals.
Claims9
A drilling fluid comprising an aqueous suspension of clay particles, sodium hydroxide for pH control, lignite as a deflocculant, polyanionic cellulose as a solid control agent, a finely-ground calcium montmorillonite clay/silica mixture as a viscosifier, and a composition comprising 0.01% to 5% of said drilling fluid by mass;
- wherein:
- (a) said composition comprises nanocellulose covalently bonded to first and second polymers;
- (b) said nanocellulose comprises cellulose particles 1 μm or less in length, and 100 nm or less in diameter;
- (c) said first polymer is negatively charged at pH 7.5-10;
- and
- (d) said second polymer is positively charged at pH 7.5-10.
Dependencies are inferred from the claim text.