Abstract
ZID16PM, a zwitterionic hydrophobic associating polymer, has equivalent positive and negative charges and some hydrophobic monomers with twin-tailed long hydrophobic chains. It exhibits a great heat resistance and salt tolerance to the common salt in formation brine (MgCl2, CaCl2, NaCl, and KCl), which is attributed to its anti-polyelectrolyte effect and strong association force. High-salinity water (seawater or formation water) can be prepared as a fracturing fluid directly. In this paper, the formation water of the West Sichuan Gas Field is directly prepared into fracturing fluid with a concentration of 0.3% ZID16PM (Fluid-1), and the seawater of the Gulf of Mexico is directly prepared into fracturing fluid with a concentration of 0.3% ZID16PM (Fluid-2). Finally, rheological measurements, proppant suspension tests, and core matrix permeability damage rate tests for the Fluid-1 and Fluid-2 are conducted. Results show that after 120 min of shearing at 140 and 160 °C, respectively, the viscosity of Fluid-1 remains in the range of 50–85 mPa·s, and the viscosity of Fluid-2 remains in the range of 60–95 mPa·s. And the wastewater produced by an oilfield in Shaanxi, Xinjiang, and Jiangsu are also prepared into fracturing fluids with a concentration of 0.3% ZID16PM, the viscosity of these fracturing fluids can remain 32, 42, and 45 mPa·s, respectively, after 120 min of shearing at 160 °C. All results demonstrate that the polymer ZID16PM displays prominent performance in fracturing fluids.
Highlights
Hydraulic fracturing technology has developed greatly over recent decades and has been the most commonly applied reservoir stimulation method for low permeability reservoirs
The resonances of protons are as follows: 4.70 (D2 O) for the solvent peak; 0.793 ppm (b) for the methyl proton peak attached to the hydrophobic chain of DiC16 AM; 0.932 ppm (a) for the methyl proton peak attached to the carbon atom of DMC and DiC16 AM; 1.088–1.119 ppm and 3.537–3.610 ppm for ethanol solvent peaks; 1.170–1.243 ppm (e) for the methylene peak of DiC16 AM; 1.361–1.471 ppm (k) for the methyl proton peak of AMPS; 1.480–1.782 ppm (c) and 2.010–2.334 ppm (d) for
–CH2 –C–) on the main chain; 3.128 ppm (g) for the methyl proton peak attached to the quaternary ammonium of DMC; 3.152–3.227 ppm (j) for the methylene peak attached to the sulfonic acid foundation group of AMPS; 3.418–3.469 ppm (i) for the methylene peak attached to the quaternary ammonium of DMC; 3.712 ppm (f) for the methylene peak attached to the tertiary amine of DiC16 AM; 3.958–4.016 ppm (h) for the methylene peak attached to the oxygen atom of DMC
Summary
Hydraulic fracturing technology has developed greatly over recent decades and has been the most commonly applied reservoir stimulation method for low permeability reservoirs. Due to the shortage of freshwater resources in inland and offshore areas, it is sometimes necessary to prepare fracturing fluids directly with high-salinity water (seawater or formation water) or oilfield wastewater [15]. ZID16 PM, a kind of zwitterionic hydrophobic associating polymer, is designed and synthesized in this paper It has an anti-polyelectrolyte effect and can be used in high-salinity water. The design calls for using acrylamide as the main polymerization monomer, and the commonly used and widely available salt-tolerance anionic monomer 2-acrylamide-2-methylpropanesulfonic acid (AMPS) and cationic monomer methacrylatoethyl trimethyl ammonium chloride (DMC) are introduced into the polymer chain. The study of zwitterionic hydrophobic associating polymers with excellent temperature-tolerance and salt-tolerance is of great significance to the development of oil and gas resources
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