Alkali-resisting polymer for displacement of reservoir oil of oil field and preparation method thereof

Abstract

The invention discloses an alkali-resisting polymer for displacement of reservoir oil of an oil field and a preparation method thereof. The alkali-resisting polymer is prepared from the following components in parts by weight: 70-130 parts of acrylamide, 10-25 parts of a negative ion monomer, 2-5 parts of a hydrophobic monomer, 2-6 parts of an alkali-resisting monomer, 0.1-0.6% of a surfactant, 13-26 parts of sodium carbonate and 200-400 parts of deionized water. The preparation method disclosed by the invention comprises the following steps: preparing an aqueous solution by acrylamide; adding sodium carbonate, negative ion monomer, hydrophobic monomer, alkali-resisting monomer and surfactant; transferring into a reactor; introducing nitrogen for 30 minutes; adding a 1# initiator; continuously introducing nitrogen for 10 minutes; adding a 2# initiator; introducing nitrogen for 10 minutes and adding a 3# initiator; continuously introducing nitrogen till the temperature is raised to 1-2 DEG C; stopping introduction of nitrogen; raising the temperature to peak temperature and insulating for 6 hours; and cutting, granulating, drying and crushing. By adding the alkali-resisting monomer into the alkali-resisting polymer disclosed by the invention, the viscosity of the product is not reduced in a ternary system. The viscosity retention rate for 90 days is over 80%.

Description

technical field [0001] The invention relates to the technical field of oil field flooding, in particular to an alkali-resistant polymer used for oil field flooding and a preparation method thereof. Background technique [0002] At present, many water flooding oil fields in China have entered the middle and late stages. Due to the heterogeneity of reservoirs and unfavorable mobility ratio in this period, there is still a large amount of remaining oil in the strata after water flooding, which is generally manifested as high water cut in oil wells. The output is low and the economic benefits of exploitation are poor. In order to ensure the stable production of the oil field, increase production and solve the contradiction between oil production and market demand, chemical flooding is a constant and beneficial method of enhancing oil recovery, mainly including polymer flooding, Alkali / polymer flooding, alkali / polymer / surfactant flooding. [0003] At present, the conventional li...

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Problems solved by technology

[0003] At present, the conventional linear polyacrylamide has the following problems in the environment of high salinity and high alkalinity: first, under the condition of high salinity and high salt, the viscosity-increasing ability of the partially hydrolyzed polyacrylamide solution is significantly reduced; Valence cations such as calcium and magnesium can precipitate with the carboxyl groups on the molecular chain of polyacrylamide under certain conditions; second, polyacrylamide solution is easily hydrolyzed under alkaline conditions, and the viscosity decreases sharply after hydrolysis, and linear polyacrylamide is not resistant to high temperature, not resistant to shearing, and not resistant to alkali; therefore, in order to stabilize oil production in oilfields, improve oil recovery, and ensure economical oil recovery, oilfields urgently need a polymer with a relatively high viscosity retention rate in a ternary environment.

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