A Crosslinkable Synthetic-Polymer System for High-Temperature Hydraulic-Fracturing Applications

A new hydraulic-fracturing fluid has been developed that is capable of reaching fluid service temperatures up to 232 degrees C. This fracturing fluid technology uses a synthetic polymer that is crosslinkable with metal ions to generate high viscosity. The synthetic-polymeric fracturing gel overcomes the thermal limitations of traditional guar and derivatized guar-based fracturing fluids. Several advancements have been made in the development of this technology to maximize the efficiency of crosslinking and to give an effective breaking profile, resulting in good laboratory gel cleanup in the proppant pack. Research efforts have yielded a fracturing fluid with good fluid stability at high temperatures to create better proppant transport and placement in these most-demanding environments. An integral part of this fluid is a crosslinking system that can be tuned for crosslinking onset from 38 to 138 degrees C, allowing for optimization for particular well conditions. The crosslinking system allows the treatment schedule to be tailored to the targeted well to help minimize frictional pressure loss. An efficient and effective oxidative-breaker package has been developed to give a controlled rheological break for the synthetic fluid and provide good regained conductivity data. The new, high-temperature fracturing technology provides a new tool to stimulate hotter, deeper hydrocarbon resources to help maximize hydrocarbon recovery. This fracturing-fluid system has been applied successfully in south Texas at temperatures approaching 232 degrees C. Laboratory rheological data that demonstrate fluid stability, crosslinking performance, and controlled fluid breaks are presented. Dynamic fluid-loss and regained-conductivity data are also presented to illustrate fluid cleanup in proppant packs.