Lignin-containing cellulose nanomaterials produced by microwave-assisted deep eutectic solvent treatment as rheology modifiers for fracturing fluids

Abstract

Fracturing fluids used hydraulic fracturing in energy industry are formulated to have superior rheological properties for suspending and transporting rigid proppants into the fractures. Herein, we report the utilization of lignin-containing cellulose nanomaterials (LCNMs) to enhance the rheological properties of viscoelastic fracturing fluids (VFFs) based on borax-crosslinked guar gum (GG) gels. Two types of LCNMs, i.e., lignin-containing cellulose nanofibers (LCNFs) from energy cane bagasse and nanocrystals (LCNCs) from bleached wood pulp were manufactured using microwave-assisted deep eutectic solvent (MV-DES, choline chloride and lactic acid) pretreatment combined with high-pressure homogenization (HPH). The resultant LCNFs and LCNCs showed fibril- and rod-like morphology with lignin content of 13.7 % and 5.9 %, respectively; and their suspensions exhibited the typical shear-thinning behaviors and gel-like viscoelastic properties. Benefited from the superior rheology of LCNMs and hydrogen bonding formed between LCNMs and GG, the presence of LCNMs significantly increased the zero-shear viscosity, yield stress, shear-thinning capacity as well as thermal stability of GG-VFFs. LCNM/GG-VFFs exhibited outstanding proppant-suspending capacity as demonstrated by sand particles being uniformly dispersed in the fluids without settling after standing for 24 h at 25 and 80 ℃. • The morphologies of lignin-containing cellulose nanomaterials (LCNMs) are affected by the lignin content in origins. • LCNMs are utilized as rheology modifiers in the guar gum-viscoelastic fracturing fluids (GG-VFFs). • GG-VFFs with the addition of LCNMs exhibited outstanding proppant-suspending capacity.