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In this study, a salt-resistant hydrophobic association polymer (PZDY) is synthesized by acrylamide, octadecyl dimethylallyl ammonium chloride and decane polyoxyethylene ether acrylate by aqueous polymerization. The infrared spectroscopy, fluorescence spectroscopy, scanning electron microscopy and other characterization methods were used to study its properties, and the rheological properties of PZDY solution is analyzed. The results showed that when concentration of NaCl is less than 5 wt% and CaCl2 is less than 1 wt%, the viscosity of 0.4 wt% PZDY increases with the increase of salt concentration. When the salt concentration continued to increase, the PZDY viscosity gradually decreased. Investigation of the rheological behavior showed that 0.6 wt% PZDY in 5 wt% NaCl and 1 wt% CaCl2 solution, could withstand a temperature up to 180 °C, after being sheared for 2500 s at 170 s−1, and its viscosity was greater than 50 mPa·s. Moreover, the viscosity of 0.6 wt% PZDY in 5 wt% NaCl increased from 104 to 205 mPa·s and the viscosity of 0.6 wt% PZDY in 1 wt% CaCl2 increased from 110 to 157 mPa·s, when at a shear rate of 170 s-1, at 180 ° C and the shear time was less than 500 s. Meanwhile, SEM results showed that salt addition enhanced the quasi-spatial network structure, with closer clustering of PZDY molecules in NaCl solution than in CaCl2 solution. The storage modulus (G′) and loss modulus (G") increased with the increase of PZDY concentration. Therefore, PZDY can be used to improve the heat and shear resistance of fracturing fluids and enhance oil recovery.

In this study, stearyl alcohol polyoxyethylene ether (AEO) and 2-isocyanatoethyl methacrylate (IEM) are used to synthesize reactive carbamate surfactants (IEM-nAEO), which are characterized through Fourier-transform infrared spectrometry and nuclear magnetic resonance spectroscopy. Additionally, the influence of the AEO-chain content on surface activity is analyzed, and the emulsifying ability of the surfactants is investigated. The surfactants exhibit high surface activities, and their emulsifying abilities enhance upon increasing the AEO-chain content. Additionally, a novel hydrophobically associative polymer is synthesized by copolymerizing IEM-10AEO, acrylamide, 2-acrylamido-2-methylpropane sulfonic acid, and acrylic acid; the rheological properties of its aqueous solution is analyzed. The modified and unmodified polyacrylamide solutions exhibit viscosity retentions of 97.73% and 87.07%, respectively, at 120 C at a shear rate of 170 s À1 . Thus, IEM-10AEO polymerization improves the heat and shear resistance and storage and loss moduli of the polyacrylamide, indicating structural-stability enhancement upon polymerization. Therefore, the modified polyacrylamide can be used to improve the heat and shear resistance of fracturing fluids and enhance oil recovery.

In the wake of increasingly serious challenges in oilfield production and energy utilization, oil and gas reservoirs with ultra‐low permeability have gained tremendous importance for global energy supply. In such reservoirs, hydraulic fracturing is an important stimulation measure. Here, to develop a high‐performance fracturing fluid, a novel type of water‐based thickener named FPM‐2 was exploited based on low‐molecular weight alcohol and hydrophobically associating polymers, labeled as AAOS, and synthesized using acrylamide, acryloyl acid, octadecyl dimethyl allyl ammonium chloride, and octadecyl methacrylate. Dissolution rate and scanning electron microscope results showed the system to be a fast‐soluble thickener with a spatially cross‐linked network structure. The viscosity of 0.8 wt% FPM‐2 reached up to 216 mPa·s. Investigation of the rheological behavior showed that the thickener, 1.4 wt% FPM‐2, could withstand a temperature up to 180°C after being sheared for 80 min at 170 s−1, and its viscosity was up to 53 mPa·s. The 0.6 wt% FPM‐2 sample also displayed excellent shear recovery properties and high viscoelasticity. The most fascinating aspect of FPM‐2 was that its unique formula imparted the thickener with characteristics such as enhanced self‐association, waterproof locking, and prevention of wax formation. In this research, the recovery value of core permeability exceeded 80%, and wax was precipitated as small‐sized particles that prevented pipeline blockage. Therefore, the use of this multi‐effect cleansing thickener should set the trend for the development of oil and gas resources.