Cu/Bentonite Nanohybrids Prepared by Thermal Decomposition and Their Enhancement Mechanism for High-Temperature Tribological Properties of Water-Based Drilling Fluids

Abstract As oil and gas drilling extends to deep complex formations, water-based drilling fluids urgently need enhanced lubricity to lower friction, torque loss and drill string wear. In this work, Cu/bentonite (Cu/Bent) nanohybrids were synthesized via thermal decomposition with bentonite as the carrier. Structural characterizations verified uniform loading of Cu nanoparticles on bentonite to form stable hybrid structures. Tribological, high-temperature and salt resistance tests showed that Cu/Bent as a water-based drilling fluid lubricant delivered remarkable friction-reduction and anti-wear effects. Before aging, its addition reduced the friction coefficient by 86.9% and wear rate by 82.4%. After 240 °C thermal aging and in high-salt environments, it still maintained superior lubrication capacity. ts outstanding performance stems from the deposition of nano-Cu on friction surfaces and the formation of a composite friction film, which isolates contact interfaces and weakens friction. This research offers a novel reference for high-performance lubricants for deep well drilling fluids.