Novel approaches to cross-linking high molecular weight polysaccharides: Application to guar-based hydraulic fracturing fluids

We report on recent work carried out using computational chemistry techniques which is aimed at suggesting novel ways of improving upon current methods of handling guar-based fracturing fluids. We describe generic methods available for modelling macromolecular, polysaccharide systems and apply these methods to building representative sections of the guar polysaccharide molecule, and to study its conformations in vacuo and in aqueous solutions using molecular dynamics. We then propose some novel cross-linking agents which differ from most of those currently under consideration in that they are extended, linear molecules related to polyethers. Representative cross-linking agents are then prepared and tested with various guar preparations. This study shows that with the correct choice of cross-linking agent, the overlap concentration C* can be reduced below the expected level for particular guars.