Abstract
Comprehending the percolation law of polymer solutions in porous media is the basis of effective application of polymer flooding. The solution properties of partially hydrolyzed polyacrylamide (HPAM) and the hydrophobically associating polymer AP-P4 were compared, and the seepage characteristics in porous media were studied. The results showed that HPAM is a viscoelastic fluid dominated by a viscosity modulus. The smaller hydrodynamic size (≥3 µm) and low adsorption capacity (200 µg/g) caused an increase in the resistance factor of HPAM in porous media with the increase in injection velocity. Hydrophobic association greatly improved the solution properties of the polymer, with a stronger apparent viscosity, elastic modulus, hydrodynamic size (≥10 µm), and adsorption capacity (780 µg/g), showing that the viscoelastic fluid properties were dominated by the elastic modulus. The resistance factor of the polymer solution in porous media decreased with the increase in injection velocity.
Highlights
INTRODUCTIONThe application of polymers in oil displacement has mainly been in porous media, which greatly improves the performance of the solution, and the seepage law of polymers in porous media will change obviously
The mechanism of polymer flooding improves the oil displacement efficiency and sweep efficiency by increasing the effective viscosity of the displacement phase and reducing the permeability of the displacement phase.1,2 polymer flooding is a widely used Enhanced Oil Recovery (EOR) technology in the later stage of water flooding reservoir development.3,4 To meet the demands of reservoir application, polymer synthesis technology has been developed and is mainly divided into the following types: improving the molecular weight and improving the molecular modification
Some scholars have found that the rheological characteristics of polymer solution in porous media under certain conditions do not fully conform to the pseudoplastic fluid characteristics of “shear thinning,” and many characteristic phenomena are observed such as “shear thickening.”17–20 Based on a comparison of the research results obtained by these scholars, it has been observed that the “shear thickening” phenomenon is mainly due to the enhancement of the elastic action characteristics of the polymer solution, which leads to an increase in its effective viscosity in porous media and can be defined as the tensile viscosity of the polymer
Summary
The application of polymers in oil displacement has mainly been in porous media, which greatly improves the performance of the solution, and the seepage law of polymers in porous media will change obviously. Some scholars have found that the rheological characteristics of polymer solution in porous media under certain conditions do not fully conform to the pseudoplastic fluid characteristics of “shear thinning,” and many characteristic phenomena are observed such as “shear thickening.” Based on a comparison of the research results obtained by these scholars, it has been observed that the “shear thickening” phenomenon is mainly due to the enhancement of the elastic action characteristics of the polymer solution, which leads to an increase in its effective viscosity in porous media and can be defined as the tensile viscosity of the polymer.. Some basic data were provided for the application of polymer flooding technology
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