This invention relates to methods for preparing slurries that include depolymerized polysaccharides and depolymerized and derivatized polysaccharides that may be useful in subterranean well operations including fracturing, gravel packing, and frac-packing. One embodiment of the present invention provides a method for making a slurry, comprising combining a polysaccharide with an organic solvent to form a slurry; and, depolymerizing the polysaccharide in the slurry. Another embodiment of the present invention provides a method of treating subterranean formation with slurry comprising the steps of creating a slurry using a method comprising the steps of combining a polysaccharide with an organic solvent to form a slurry; and, depolymerizing the polysaccharide in the slurry; and, placing that slurry into a subterranean formation.