Abstract
Water-soluble polymers are widely used in oilfields. The rheological behaviors of these polymers in high-salinity solution are very important for stimulation of high-salinity reservoirs. In this work, a novel thermal-resistant and shear-stable amphoteric polyacrylamide (PASD), prepared from acrylamide (AM), sodium styrene sulfonate (SSS), and acryloxyethyl trimethylammonium chloride (DAC) monomers, was prepared by free-radical polymerization in high-salinity solution. The amphoteric polyacrylamide was characterized by Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance spectroscopy (1H NMR), elemental analysis, thermogravimetric analysis (TG), and scanning electron microscopy (SEM). The amphoteric polyacrylamide exhibited excellent salinity tolerance. The slow increase in apparent viscosity of the polymer with increase in salinity was interesting. The amphoteric polyacrylamide showed perfect temperature resistance in high-salinity solution. The viscosity retention reached 38.9% at 120 °C and was restored to 87.8% of its initial viscosity when temperature was decreased to room temperature. The retention ratio of apparent viscosity reached 49.7% at 170 s−1 and could still retain it at 25.8% at 1000 s−1. All these results demonstrated that PASD had excellent thermal-resistance and shear-stability in high-salinity solution. We expect that this work could provide a new strategy to design polymers with excellent salinity-tolerance, thermal-resistance, and shear-stability performances.
Highlights
Water-soluble polymers have been intensively explored, due to their practical importance as viscosity-enhancing agents, flocculating agents, food additives, etc. [1,2]
This paper presents the design and synthesis of an amphoteric polyacrylamide
There was a dramatic increase in temperature and viscosity, which indicated that gelation increased with increase in monomer concentration
Summary
Water-soluble polymers have been intensively explored, due to their practical importance as viscosity-enhancing agents, flocculating agents, food additives, etc. [1,2]. Polyampholytes have been used in petroleum explorations He [30] synthesized an amphiphilic copolymer containing acrylamide, acrylic acid, 2-acrylamido-2-methyl propane sulfonic acid, and modified β-cyclodextrin to be an oil displacement agent, which showed good temperature resistance and oil displacement ability. Synthesized a high molecular-weight polyampholyte containing acrylamide, sodium acrylate, and diallyl dimethyl ammonium chloride as a fracturing fluid thickener These studies indicate that the polyampholyte has excellent thickening ability in solution at high temperatures. The cationic monomer, acryloxyethyl trimethyl ammonium chloride (DAC), can inhibit the hydration swelling ability of clay minerals, and its bulky side chains can boost the salinity tolerance and shear-stability [34] Both SSS and DAC are cheap and undergo copolymerization actively. Detailed rheological properties in high-salinity solution have been studied
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