Instant-dissolved cationic polyacrylamide capsulation agent and preparing method thereof

Abstract

The invention belongs to the field of cationic polymer capsulation agents, and relates to an instant-dissolved low-molecular-weight polyacrylamide capsulation agent and a preparing method thereof. The capsulation agent is prepared from three monomers in a copolymerization mode, wherein the first monomer is one of acrylamide and sodium acrylate, the second monomer is one of cationic monomers including dimethyl diallyl ammonium chloride, diethyl diallyl ammonium chloride, acryloxyethyl ethyl dimethyl benzyl ammonium chloride, methacryloyl oxyethyl dimethyl-benzyl ammonium chloride and methacryloyloxyethyl trimethyl ammonium chloride, and the third monomer is one of hydroxyethyl methylacrylate and hydroxypropyl methacrylate. The molecular structures of the monomers contain hydroxyl, the hydroxyl can interact with drilling cuttings, and the capsulation inhibiting performance is improved. According to the capsulation agent, the inverse emulsion polymerization technology is adopted, the aftertreatment technology is simple, the granular product can be conveniently stored for a long time and transported, the dissolving time is short in use, convenience is brought to site utilization, the capsulation inhibiting effect is good, and the performance of a drilling fluid system can be improved.

Description

technical field [0001] The invention relates to an instant cationic polyacrylamide coating agent and a preparation method thereof, in particular to a low molecular weight cationic polyacrylamide coating agent and a preparation method thereof. Background technique [0002] Coating agent is an important component in polymer drilling fluid. The addition of polymer coating agent can prevent clay from dispersing, and its molecules can quickly adhere to the surface of drilling cuttings and clay to play the role of coating and flocculation. And it can also form internal and external mud cakes on the well wall to reduce pressure difference transmission and filtrate penetration. The coating agent can effectively inhibit the hydration and dispersion of drilling cuttings and the well wall, so as to maintain the stability of the well wall, remove useless solid phase, and maintain low solid phase. [0003] At present, the polyacrylamide coating agent used in common oilfield drilling flu...

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Problems solved by technology

This type of coating agent has the ability to coat the cuttings and prevent the hydration and dispersion of the cuttings, but the high molecular weight coating agent causes the viscosity of the system to increase when used (Fan Yufu, Journal of Shengli College, China University of Petroleum, 2008, 22(1 ):4-5), and excessive flocculation is prone to occur, resulting in increased mud filtration loss and unstable mud performance; and due to the large molecular weight, powdery coating agents tend to form insoluble clumps when dissolved , It takes a long time to completely dissolve, and the speed is slow, which seriously affects the construction progress

Polymers with relatively low molecular weight have a short dissolution time and can meet the requirements of on-site operations, such as the ULTRACAP products of foreign Microbar companies, but they are expensive and used in large quantities, resulting in high drilling fluid costs

On the other hand, there are a large number of silanol groups on the surface of shale, drilling cuttings and clay, and the molecular structure of general polyacrylamide coating agents lacks groups that can interact with them, and the coating inhibition effect needs to be further strengthened

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