Wood-derived lignocellulose nanomaterials as multifunctional agents in eco-friendly pickering emulsion-based drilling fluids

Emulsion-based drilling fluids are critical in the development of oil and natural gas from unconventional reservoirs due to their superior wellbore stabilizing capacity, good erosion resistance, and excellent lubricity. However, their widespread applications have been limited by the stringent environmental regulations and poor emulsion stability caused by hazardous, non-biodegradable oils and surfactants that have weak tolerance to temperature, pH, and salts. To address these concerns, an eco-friendly and high-performance Pickering emulsionbased drilling fluid has been developed, which includes sunflower seed-derived biodiesel as the oil phase, woodderived lignocellulose nanomaterials (i.e., cellulose nanofibers-CNFs, cellulose nanocrystals-CNCs, and lignin nanoparticles-LNPs) as solid stabilizers, and bentonite as viscosifiers and fluid loss reducers. By tailoring the physicochemical characteristics and the synergistic effect of lignocellulose nanomaterials, the droplet size and stability of the emulsion can be well adjusted. The as-formulated drilling fluid exhibits desirable rheology and filtration performance, and can be used to cultivate paddy rice without treatment. The introduction of CNFs promotes soil loosening and nutrient absorption, leading to enhanced cultivation performance. This work may open a new avenue for the development of eco-friendly and high-performance drilling fluids using fully biomassderived feedstocks.