Nanosilica dispersion in water-based mud: Balancing sonication and mixing energy for optimized particle dynamics and fluid performance

Abstract

Sustainable drilling fluids are critical for subsurface energy and resources extraction. These drilling applications include oil and gas, geothermal energy, carbon storage, and rare earth in-situ mining. Environmental challenges and the high cost of oil-based muds demand sustainable, nanoparticle-enhanced water-based drilling fluids. However, the current API standards lack protocols for nanoparticle dispersion in drilling fluids. This study addresses this critical gap by systematically optimizing particle size distribution (PSD) through controlled sonication and high-shear mixing. Particle characterization and morphology were analyzed using dynamic light scattering, laser diffraction, dynamic image analysis, and scanning electron microscopy.

High-shear mixing improved the yield point of the base mud by 22 % with the Hamilton Beach Mixer (HBM) and 23 % with the Waring Blender (WB), while the 10-min gel strength increased by 19 % and 20 %, respectively. Filtrate loss over 30 min decreased by 16 % with the HBM and 25 % with the WB, driven by WB extensive particle size reduction of 52 % at high shear, compared to 39 % for the HBM. Results show that doubling the mixing speed halved the time required to reach similar particle sizes. Sonication reduced the hydrodynamic diameter of nanosilica clusters from an initial 960 nm at 2.5 min to 471 nm after 30 min, a 51 % reduction, compared to the manufacturer-reported dry individual particle size of 60–70 nm. The developed decay functions effectively modeled the effects of mixing and sonication on particle size reduction and helped optimize dispersion energy. Optimized nanosilica-enhanced mud, prepared with 2.5 min of sonication at 50 % amplitude and 30 min of high-shear mixing at 11,000 RPM using the WB, achieved a 48 % higher yield point (6.8–13.1 lb/100 ft²), 39 % improved filtration efficiency (20.2–14.5 mL), and 24 % thinner mud cake (1.36–1.8 mm) compared to under- or overmixed samples. Optimal performance was achieved at a 33 % nano-to-micro size ratio when nanosized barite particles were reduced by 53 % in size, and their specific surface area increased by 97 %, which bridged the shape and size gap between nanosilica agglomerates and bentonite sheets.

This study provides practical strategies for optimizing nanoparticle dispersion and refining energy-efficient drilling fluid mixing protocols. Improved particle dynamics bridged nanosilica and microsized additive gaps. These findings establish a foundation for next-generation fluids, drive advancements in API standards, and enhance field applications in geoenergy systems.