Synthesis and Study of an AM/AA/SMA Hydrophobically Associating Polymer Used as Thickening Agent in Fracturing Fluids

Hydrophobically associating polymers have found wide applications in oil and gas production because of their unique rheology, high temperature stability and good shear-resistance. A hydrophobically associating polymer HAPAM has recently been synthesized in laboratory with stearyl methacrylate (SMA) as the hydrophobic monomer, and AM and AA as water soluble monomers, through micellar polymerization. The optimum conditions for the synthesis reaction were as follows:the mass ratio of the monomers was 0.3%, pH=6, the mass of SMA was 0.4% of the total mass of monomers, the mass of SDS was 30% of the mass of SMA, and the concentration of chain transfer agent (sodium formate) was 2 mg/L. Laboratory studies on the properties of HAPAM with IR spectroscopy, fluorescence, UV spectroscopy and rotary viscometer showed that HAPAM had hydrophobically association groups in its molecules, and the critical association concentration was ca. 0.5 mg/mL. HAPAM had good water solubility, thickening capacity, shearresistance, and better high temperature performance and salt-resistance than PAM synthesized at the same conditions. Crosslinking reactions of HAPAM with different chemicals showed that organic zirconium was the best crosslinking agent. It is concluded that HAPAM, as a thickening agent for use in fracturing fluids, is worth further extensive studying.