Core-Shell Structured Ultrahyperbranched Polymer Based Hydraulic Fracturing Fluid Crosslinker

Hydraulic fracturing operation has been widely used in oil and gas industry production applications. Fracturing fluid plays a key role in transiting pressure, transporting proppant and minimizing possible leaking during the job, with thickeners and crosslinkers together to enhance fluid viscosity. Commercial crosslinkers are mostly borates or inorganic salts. Some polymeric crosslinker have also been used for guar gum and polyacrylamide (PAM) thickeners.<br/>When compared with linear and branched polymers, hyperbranched polymers have attracted significant attention due to their extraordinary properties, such as a lower viscosity, higher solubility, smaller size and higher surface functional group concentrations. Such properties make hyperbranched polymers potential candidates for downhole applications with low formation damage.<br/>This paper demonstrated the A to Z for a novel core-shell structured ultrahyperbranched polymer (UHP) for applications of hydraulic fracturing fluid crosslinker. The UHP was designed and synthesized by growing a hyperbranched polymer shell structure from the surface of a pre-existing hyperbranched polymer core that acts as a macroinitiator. Characterizations for UHPs have been performed, such as FT-IR, NMR and GC-MS. Gelation properties with fracturing fluids were tested with rheometer following ISO 13503-1 method. Multiple functional groups were tested for different conditions. The synthesized UHPs have been approved potential crosslinkers for polymer based fracturing fluids.<br/>The UHP crosslinkers will be further investigated for compatibility with current fracturing fluid package and tested in the field for future fracturing operations.