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Polymer solution for oil displacement is mostly used in the middle and late stage of water flooding reservoir development, and reservoir groundwater conditions are often one of the main conditions restricting polymer application. Therefore, it is necessary to develop salt tolerance of polymer solutions with different aggregation behaviors, so as to facilitate the synthesis and optimization of suitable polymer systems. The differences in the micro‐aggregation behavior of three polymers with different molecular structures were explored. On this basis, the effects of divalent metal cations on the properties of the polymer solutions were analyzed by assessing the micro‐aggregation behavior, apparent viscosity, hydrodynamic size, and shear rheological characteristics. The results showed that the linear partially hydrolyzed polyacrylamide (HPAM) was seriously affected by divalent cations, and the viscosity decreased obviously. The aggregation behavior of the polymer changed by hydrophobic association can enhance the salt tolerance of the solution. The hydrophobically modified partially hydrolyzed polyacrylamide (HMPAM) with "chain beam" aggregation behavior has strong intermolecular connection, which enables it to withstand the content of calcium and magnesium ions of 1100 mg l−1. When the content of calcium and magnesium ions exceeds 600 mg l−1, dendritic hydrophobically associating polymer (DHAP) will destroy the interaction between molecular chains, resulting in the decrease of apparent viscosity and hydrodynamic size. For polymer flooding in high‐salinity reservoir, salt tolerant polymer system can be constructed by optimizing molecular weight and hydrophobic group content. [ABSTRACT FROM AUTHOR]

The study of polymer aggregation behavior effect on shear resistance shed light on the synthesis of antishear polymer for oil displacement and enhances the application effect of polymer flooding. The effects of mechanical degradation on the properties of polymer solutions were studied by using partially hydrolyzed polyacrylamide (HPAM), hydrophobically modified HPAM (HMPAM), and dendritic hydrophobic associative polymers (DHAP), which are characterized by "granular," "chain," and "cluster" aggregation behavior, respectively. The results show that mechanical shearing can dramatically reduce the performance of polymer solution. The shearing resistance can be effectively enhanced by improving the polymer aggregation behavior. After being strongly sheared, hydrophobically associating polymers can still partially restore its network through hydrophobic association, therefore rebuild the solution viscosity. For DHAP, the broken molecular chains distribute more evenly in solution after shearing. In addition, the strength of reconstructed network structure of DHAP is better than that of HMAPM, which implies a better shear resistance. Furthermore, the hydrophobic association of linear polymers will increase their static adsorption on quartz sand. Meanwhile, DHAP with stronger spatial structure has less static adsorption, which is beneficial to maintain a higher polymer concentration in solution. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 137, 48670. [ABSTRACT FROM AUTHOR]

In recent years, gas injection, especially CO 2 injection, has been acknowledged as a promising approach for enhanced oil recovery (EOR) and CO 2 capture and storage (CCS), especially for tight reservoirs. However, when CO 2 is injected into the oil reservoirs, it can disturb the equilibrium of the system and lead to chemical reactions between CO 2 , formation water, and reservoir rocks. The reactions will alter some geochemical and physicochemical characteristics of the target reservoirs. However, the reactions still lack quantitative characterization at the pore scale, especially under reservoir conditions. Herein, we conducted an experimental study of the interactions between CO 2 , brine, and rocks in the Mahu oilfield at 20 MPa and 70 °C. The low-field nuclear magnetic resonance (LF-NMR) measurements showed that the incremental amplitude for tight cores of CO 2 -rock-water tests was larger than that for CO 2 -rock tests, and the amplitude alteration presented significant differences corresponding to different types of minerals and pores. Furthermore, the interplanar spacing of the core samples was increased with the increase of reaction time in the CO 2 -rock experiments but still lower than that in CO 2 -rock-water tests. This research demonstrated evident changes in the geochemistry in tight reservoirs caused by CO 2 , brine, and rock reactions. The results of this study may provide a significant reference for the exploration of similar reservoirs in the field of CO 2 -EOR and CO 2 sequestration., Competing Interests: The authors declare no competing financial interest., (© 2022 The Authors. Published by American Chemical Society.)

In order to further develop efficient ultraviolet light-driven photocatalysts for environmental application, α-zirconium phosphate (α-ZrP) and carbon nitride (C 3 N 4 ) were synthesized, respectively. Then, C 3 N 4 -ZrP compositing nanomaterials were prepared by compositing α-ZrP nanocrystals and C 3 N 4 with different mass ratios. C 3 N 4 -ZrP compositing nanomaterials were characterized by X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The results illustrated that α-ZrP and C 3 N 4 were successfully composited, and the polarization of the compositing nanomaterials was reduced compared with raw materials. The photocatalytic performances of C 3 N 4 -ZrP compositing nanomaterials with different mass ratios were studied by photodegradation of RhB under ultraviolet irradiation. All of the degradation rates of the C 3 N 4 -ZrP compositing nanomaterials system were achieved more than 90% after 18 min. When the mass ratio of C 3 N 4 -ZrP compositing nanomaterials is 2:1, the degradation efficiency achieved 99.95%, which is more efficient than other tested mass ratios. The result indicated the possibility of utilizing C 3 N 4 -ZrP compositing nanomaterials for environmental pollutants degradation., Competing Interests: The authors declare no competing financial interest.