Low-expansion-rate nano-level water absorption microsphere and preparation method thereof

Abstract

The invention relates to a low-expansion-rate nano-level water absorption microsphere and a preparation method thereof. The prepration method comprises the following steps: preparing a water-phase mixed liquid: uniformly mixing acrylamide, acrylic acid, a cationic monomer, a crosslinking agent and water, and then adding an alkaline substance, thus obtaining the water-phase mixed liquid; preparingan oil-phase mixed liquid: uniformly mixing an oil solvent, a hydrophobic monomer and an emulsifier, thus obtaining an oil-phase mixed liquid; performing polymerization: homogenizing the oil-phase mixed liquid, then feeding nitrogen to remove oxygen, adding an initiator to initiate the polymerization, and controlling temperature of a system to not exceed 70 DEG C through refrigeration equipment; performing post-treatment: after the polymerization reaction is ended, adding nonylphenol polyoxyethylene ether into the reacted mixed liquid, thus obtaining the low-expansion-rate nano-level water absorption microsphere. The microsphere obtained by the method is small in particle size distribution range, low in expansion rate within 30 to 100 nm; the expansion is started within 1 to 2 hours; the low-expansion-rate nano-level water absorption microsphere is particularly applicable to blocking of a special compact bottom layer block.

Description

technical field [0001] The invention relates to the technical field of profile control and water shutoff for increasing production in oilfields, in particular to nanoscale water-absorbing microspheres with low expansion speed and a preparation method thereof. Background technique [0002] The loss of the oil displacement agent system has become a widely faced problem in the exploitation of crude oil, and these problems will greatly affect the production and benefits of the oil field. In the later development process of polymer flooding, due to the existence of many tiny pores in the formation, under the high pressure conditions during the oil displacement process, the oil displacement agent permeated and lost from the pores, resulting in a lot of waste. Therefore, the problem of water plugging and profile control in oilfields is becoming more and more severe. At present, polyacrylamide aqueous solution and cross-linking agent are used most in oilfields for selective water pl...

AI Technical Summary

Problems solved by technology

[0006] Aiming at the problem that existing preparation methods cannot produce polymer microspheres with particle diameters within 100nm, the present invention provides a method for preparing nanoscale water-absorbing microspheres with low expansion speed

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