Salt-resistant polymer for oil displacement of oil field and preparation method thereof

Abstract

The invention discloses a salt-resistant polymer for oil displacement of an oil field and a preparation method thereof. The salt-resistant polymer comprises the following materials in parts by weight: 80-120 parts of acrylamide, 26-40 parts of acrylic acid, 1-5 parts of hydrophobic monomer, 1-5 parts of polyoxyethylene octadecanol ether methacrylate or polyoxyethylene hexadecanol ether methacrylate, 230-450 parts of deionized water and 0.1-0.3 part of chain transferring agent. The salt-resistant polymer and the preparation method disclosed by the invention have the advantages that in a formula of the polymer, since polyoxyethylene octadecanol ether methacrylate and the hydrophobic monomer are added for composite use, the salt resistance of the polymer is improved; in the formula of the polymer, polyoxyethylene octadecanol ether methacrylate is added, and a surface active agent does not need to be added in the synthesis process, so that the following treatment process is reduced; the viscosity retention rate of 1500ppm salt-resistant polymer solution is larger than 80% after the 1500ppm salt-resistant polymer solution is put in the solution with the degree of mineralization being 30000mg / L NaCl and 200mg / L Ca<2+> and Mg<2+>.

Description

technical field [0001] The invention relates to the technical field of oil field flooding, in particular to a salt-resistant polymer used for oil field flooding and a preparation method thereof. Background technique [0002] my country started the research on tertiary oil recovery technology in the 1960s. After the 1980s, tertiary oil recovery technology has developed rapidly. Most of my country's oil reservoirs are continental lacustrine deposits. The formation conditions are intricate, and the heterogeneity of oil layers is serious. The difference in internal permeability is large, and it has a wide application prospect to adapt to polymer flooding. [0003] Commonly used oil displacement polymers are mainly partially hydrolyzed polyacrylamide and its derivatives. Hydrolyzed polyacrylamide has poor temperature resistance. The oil effect becomes worse; the salt resistance of partially hydrolyzed polyacrylamide is poor, and polyacrylamide has a salt-sensitive effect. In the ...

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Problems solved by technology

[0003] Commonly used oil displacement polymers are mainly partially hydrolyzed polyacrylamide and its derivatives. Hydrolyzed polyacrylamide has poor temperature resistance. The oil effect becomes worse; the salt resistance of partially hydrolyzed polyacrylamide is poor, and polyacrylamide has a salt-sensitive effect. In the oil reservoir with high salinity, especially in high-priced metal ions, its viscosity will drop significantly, and even produce Precipitation, so partially hydrolyzed polyacrylamide is difficult to dispose with sewage

[0004] Polyacrylamide has strong hydrophilicity, is easy to form hydrogen bonds with water, is easy to dissolve in water, and has a large hydrodynamic volume after hydration, but due to the flexible chain of the molecular chain, it shows a random coil conformation in aqueous solution , in high-temperature and high-salinity brine, the molecular chain curls up, and the viscosity drops significantly, which makes the viscosifying effect of the polymer significantly worse, and the flexible chain is easy to be mechanically degraded, so its application is greatly restricted and cannot be used well. Applications that meet high temperature and high salinity

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