High adhesion-promotion salt resistant water-soluble copolymer, preparation method and application thereof

Abstract

The invention discloses a water soluble copolymer with high viscosity and salt resistance, and a preparation method and an application thereof. The preparation method comprises the steps of: adding acrylamide 20 weight parts, an anionic monomer or/and a cationic monomer 0.1-15 weight parts,, a vinyl polycyclic aromatic hydrocarbon 0.05-4 weight parts,, a surfactant 0.5-90 weight parts,, and deionized water 70-900 weight parts, into a three-neck reaction bottle, adjusting the solution pH to 2.5-9, introducing N2 for 30min, adding an initiator persulfate 0.001-0.2 weight parts, at 20-70DEG C, and reacting for 6-36 hours to obtain a low-molecular weight water soluble copolymer with molecular association ability, high viscosity and salt resistance, which can be used in intermediate-permeability oil reservoir and low-permeability oil reservoir development. An associated water soluble polymer oil displacement agent is obtained by preparing the copolymer into an aqueous solution with copolymer concentration of 0.3-3 g/L and surfactant concentration of 0.01-4 mmol/L, adding into a mixer with a stirring device, and stirring uniformly at room temperature; and the obtained oil displacement agent has high viscosity, salt resistance, temperature resistance and shear resistance, and can be used in intermediate-permeability oil reservoir and the low-permeability oil reservoir development.

Description

1. Technical field [0001] The invention relates to a high viscosity-increasing and anti-salt water soluble copolymer and its preparation method and application, belonging to the fields of polymer materials and enhanced oil recovery. 2. Technical background [0002] At present, the contradiction between oil supply and demand in my country is becoming more and more prominent, and there are still a large amount of crude oil in complex oil reservoirs, especially in medium and low permeability reservoirs, which seriously restricts the development effect of oilfields and the improvement of reserves production. Among all oil displacement technologies, polymer flooding can significantly increase oil recovery, and the implementation process is simple, but it is difficult to develop polymer flooding technology for medium and low permeability reservoirs. Industrial polymers suitable for the development of medium and low permeability reservoirs. Today, my country still uses water injecti...

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Problems solved by technology

At present, for ultra-high molecular weight (1.6×10 7 ~3.0×10 7 ) partially hydrolyzed acrylamide (HPAM), because the core pore throat radius R h with R g The ratio is generally less than 5, and it is easy to have structural (non-insoluble) plugging in the pore medium of medium and low permeability reservoirs, so it is difficult to apply to medium and low permeability reservoirs

In addition, the molecular weight of acrylamide-modified copolymers that can be applied to oilfield field development in China is still high molecular weight, with a molecular weight of more than 10 million, and some even as high as more than 20 million. These copolymers can only be used for permeability higher than 1000 (10 -3 μm), it is difficult to meet the requirements of medium and low permeability reservoirs

Luo Jianhui et al., Acta Petroleum Sinica, 2004, 25(2): 67-73, synthesized AM / AHPE comb copolymer (KYPAM), the molecular weight of this type of polymer is as high as 2.514×10 7 , the thickening ability in brine is more than 50% higher than the thickening ability of domestic ultra-high molecular weight polyacrylamide in brine, but comb-shaped polymers are only suitable for high-permeability reservoirs due to their strong rigidity and large hydrodynamic radius , easy to block the pore throats of medium and low permeability reservoirs

Cao Baoge et al., Drilling and Production Technology, 2006, 29(6): 33-37, researched and evaluated the AP polymer that has been applied in the oilfield field, and the random copolymerization of hydrophobic units and acrylamide. This polymer has a temperature resistance of 85°C , anti-salt 30000mg / L, but due to the higher molecular weight (1.077×10 7 ), AP cannot be used in medium and low permeability reservoirs

Geng Tongmou et al., Fine Chemical Industry 2006, 23 (8): 747-751, synthesized a ternary hydrophobic association water-soluble polymer poly(acrylamide / sodium acrylate / N, N-diallyltetradecylamine (P( AM / NaAA / DiAC 14 ), and studied its solution performance, but the critical association concentration of the copolymer is relatively high, and the apparent viscosity of the solution with a mass concentration of 4g / L is still not high. In addition, most of the current hydrophobic monomers are Hydrolyzed at a high temperature, resulting in the loss of its hydrophobic association function, making the anti-aging performance of the polymer solution poor

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