The Development and Application of an Integrated Multifunctional Salt-Resistant Thickening Agent

An integrated multifunctional salt-resistant thickening agent was synthesized with acrylamide and sodium acrylate as the main raw materials to satisfy the needs of fracturing fluids, which are formulated in blocks where only high salinity salt waters are available, for integrated requirements such as instant capacity, salt-resistance, friction reducing, high temperature and shearing tolerance, as well as cleanup. In the inverse emulsion polymerization of the thickening agent, salt-resistant monomers were used to render the thickening agent salt-resistance. Laboratory test on a fracturing fluid treated with the synthesized thickening agent has shown that the viscosity developing rate of the thickening agent in waters of salinity between 50,000 mg/L and 60,000 mg/L in 30 s was at least 85%. The fracturing fluid formulated with this thickening agent had rate of friction reduction of at least 75% at a simulated flow rate of 10 m³/min generally used in field operations. After shearing at 170 s^-1 and 90 ℃ for 90 min, the fracturing fluid still had viscosity of more than 30 mPa∙s. Without using cleanup additives, after complete gel breaking, the fracturing fluid had surface tension of at least 24.65 mN/m, interfacial tension of at least 1.06 mN/m, and residue content of less than 30 mg/L. This thickening agent has been tried on a well in block MH in Xinjiang Oilfield, the fracturing fluid was formulated with diluted saltwater from a salt lake. The different jobs can be easily switched between each other, no cleanup additives were required, and the fluid had stable properties, satisfying the needs of the field operation.