Journal of Southwest Petroleum University(Science & Technology Edition) ›› 2023, Vol. 45 ›› Issue (4): 174-184.DOI: 10.11885/j.issn.1674-5086.2020.10.10.02


Effect of Ion Composition on the Salt-tolerance Behavior of Medium-low Molecular Weight Polymers

WANG Lili1,2, LIANG Yan3, LI Wenhong1,2, YUAN Guowei1,2, CAO Miao4   

  1. 1. Exploration and Development Research Institute, Changqing Oilfield Company, PetroChina, Xi'an, Shaanxi 710018, China;
    2. National Engineering Laboratory of Low Permeability Oil and Gas Exploration and Development, Xi'an, Shaanxi 710018, China;
    3. College of Chemistry and Chemical Engineering, Southwest Petroleum University, Chengdu, Sichuan 610500, China;
    4. Sichuan Guangya Polymer Chemical Co. Ltd., Nanchong, Sichuan 637900, China
  • Received:2020-10-10 Online:2023-08-10 Published:2023-07-18

Abstract: In view of the practical problem of choosing the medium-low molecular weight salt-tolerance polymer for Changqing Jurassic reservoir with low permeability and high salinity, this paper systematically analyzed the influence of ion concentration and composition on the salt-tolerance behavior of three different medium-low molecular weight salt-tolerance polymers. The measurement results of viscosity, relaxation time, fluorescence and environmental scanning electron microscopy showed that, compared with the conventional salt-tolerance polymer SAV55 and the associative polymer EY-131 with lower molecular weight, the associative polymer BHXF-850 with higher molecular weight and associative monomer content had better viscosifying capacity. However, with the addition of Na+, Ca2+ and Mg2+, the viscosity retention rate, relaxation time and solution structure number of BHXF-850 were the lowest and the structural strength was also the weakest, and the solution microstructure was significantly affected by the addition of ions. At the same time, the salt-tolerance behavior of the polymer had no obvious difference between the addition of mono-valent and divalent ions. The findings can provide reference for the optimization of medium-low molecular weight salt-resistant polymers used for chemical flooding in reservoir fields.

Key words: Jurassic reservoir, ion composition, medium-low molecular weight, salt-tolerance polymers, relaxation time, solution structure, micro-structure

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