Preparation method of partially hydrolyzed polyacrylamide gel blocking agent

Abstract

The invention relates to a preparation method of a partially hydrolyzed polyacrylamide gel blocking agent. According to the invention, a chrome propionate cross-linking agent is prepared from materials of chromate, a reducing agent and propionic acid according to a molar ratio of 1:(2.5-5.5):(8-20), wherein a reaction temperature is 10-120 DEG C and a reaction time is 5-10h. An auxiliary agent is prepared from components of, by mass: 1-8% of C2-C5 alcohol, 0.5-1.5% of a sulfur-containing oxygen purification agent, 2-8% of polycarboxylic acid, 30-40% of sodium hydroxide, and 50-60% of distilled water, wherein a reaction temperature is 50-100 DEG C and a reaction time is 2-5h. The partially hydrolyzed polyacrylamide gel blocking agent is prepared from components of, by mass: 1-3% of partially hydrolyzed polyacrylamide, 0.2-0.6% of the chrome propionate cross-linking agent, 0.2-0.4% of the auxiliary agent, and balance of water. The auxiliary agent provides functions of retarding, stabilizing and pH value regulating.

Description

technical field [0001] The invention relates to a preparation method of a partially hydrolyzed polyacrylamide aqueous solution chromium cross-linked to form a chromium gel plugging agent for plugging a high-permeability formation and adjusting the water absorption profile of an oil field water injection formation. Background technique [0002] In the 1980s, Smith et al. used a lower concentration of partially hydrolyzed polyacrylamide and aluminum citrate for cross-linking to form a colloidal dispersion gel system, which was used in oilfield profile control operations. After more than 20 years of research, there are two types of cross-linking agents for partially hydrolyzed polyacrylamide: chelating type and covalent bond type. Among them, the chelating type is formed by metal ions such as chromium (III), aluminum (III), titanium (VI), zirconium (IV) and appropriate chelating agents (such as acetic acid, propionic acid, malonic acid, lactic acid, citric acid, etc.) Metal ch...

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Problems solved by technology

[0004] Initially, Usp4148746 discloses the use of chromium crosslinking agent to add hexavalent chromium salt (such as sodium dichromate or potassium) in the polymer aqueous solution, and then add reducing agent (such as sodium bisulfite or potassium), and the polymer aqueous solution gradually reaches Gel state, when the gel prepared by this method is applied on site, the pumping pressure will be too high. If the gel strength is too high, the pumping pressure will be too high to prevent construction; if the gel strength is small, the plugging effect will be reduced. too bad

[0005] Later, people reacted with chromate and reducing agent (such as sulfite), and then added aqueous sodium hydroxide solution to make trivalent chromium form chromium hydroxide. After separation and purification, pure chromium hydroxide was obtained, and then combined with organic acid (such as Acetic acid, propionic acid, lactic acid, etc.) are reacted to obtain organic chromium cross-linking agent. The main problem of this process is: a large amount of water will be used when synthesizing and separating and purifying chromium hydroxide, and these waters will eventually become sewage containing a certain concentration of trivalent chromium

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