Thermothickening Drilling Fluids Containing Bentonite and Dual-Functionalized Cellulose Nanocrystals
Mei‐Chun Li, Qinglin Wu, Tingzhou Lei, Changtong Mei, Xinwu Xu, Sunyoung Lee, Jaegyoung Gwon
Abstract
The approaching era of sustainable development and rapid increase in global energy demand necessitates the development of high-performance drilling fluids with low toxicity, sustainability, and in-situ rheology controllability for complicated formation excavation. Herein, smart water-based drilling fluids (WDFs) with thermocontrollable rheological properties are developed using bentonite (BT) and dual-functionalized cellulose nanocrystals (fCNCs). The fCNCs are synthesized by surface grafting of poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPS) and poly(N-isopropylacrylamide) (PNIPAM) through free-radical graft polymerization. The presence of PAMPS grafts with abundant amide and negatively charged sulfonate groups not only enables fCNCs to attach on the surface of BT platelets creating BT/fCNC clusters but also ensures the created BT/fCNC clusters to uniformly disperse through electrostatic repulsion. On the other hand, the introduction of thermoresponsive PNIPAM grafts induces the association of BT/fCNC clusters at elevated temperatures through enhanced hydrophobic attraction, resulting in promising thermothickening rheological performance of BT/fCNC-WDFs. Furthermore, the thermothickening rheological behavior can be maintained even after 10 heating/cooling cycles, albeit with a slight increase in the critical transition temperature. The developed BT/fCNC-WDFs with sustainability, in-situ rheology controllability, and good cyclability have great potential in the smart drilling industry, making the exploration and production of oil and gas more safe, efficient, and environmentally friendly.