阅读说明：本技术 一种疏水缔合聚物及其制备方法及用于耐高温压裂液 (Hydrophobic association polymer, preparation method thereof and application of hydrophobic association polymer in high-temperature-resistant fracturing fluid ) 是由 毛金成 徐涛 林冲 毛金桦 杨小江 于 2019-10-18 设计创作，主要内容包括：本发明公开了一种用于油田压裂液及提高采收率的缔合聚合物及其制备方法。其制备方法包括：(1)将0.05molβ-环糊精和0.05mol马来酸酐溶于N,N-二甲基甲酰胺中,在80℃反应10小时,得到单体MAH-β-CD；(2)在冰浴中将0.1mol N,N-双十二胺和6N氢氧化钠(50ml)加入二氯甲烷中并通入干燥氮气,用恒压漏斗将甲基丙烯酰氯(0.104mol)缓慢加入到二氯甲烷的混合溶液中,搅拌2小时,得到单体DiC<Sub>12</Sub>AM；(3)将单体MAH-β-CD和DiC<Sub>12</Sub>AM与丙烯酰胺,丙烯酸和2-丙烯酰胺基-2-甲基丙磺酸加入到去离子水中,通氮气半小时,升温至45～60℃并加入引发剂,聚合反应6～8h即得到疏水缔合聚合物。用该聚合物制备的压裂液具有良好的增稠能力和抗温性,在油田压裂液及提高采收率中具有较好的应用前景。(The invention discloses an associated polymer for an oil field fracturing fluid and an enhanced recovery ratio and a preparation method thereof. The preparation method comprises the following steps: (1) dissolving 0.05mol of beta-cyclodextrin and 0.05mol of maleic anhydride in N, N-dimethylformamide, and reacting at 80 ℃ for 10 hours to obtain a monomer MAH-beta-CD; (2) 0.1mol of N, N-didodecylamine and 6N sodium hydroxide (50ml) were added to dichloromethane in an ice bath and dry nitrogen was passed through, methacryloyl chloride (0.104mol) was slowly added with constant pressure funnelAdding into mixed solution of dichloromethane, stirring for 2 hours to obtain monomer DiC 12 AM; (3) monomeric MAH-beta-CD and DiC 12 And adding AM, acrylamide, acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid into deionized water, introducing nitrogen for half an hour, heating to 45-60 ℃, adding an initiator, and carrying out polymerization reaction for 6-8 hours to obtain the hydrophobic association polymer. The fracturing fluid prepared from the polymer has good thickening capacity and temperature resistance, and has good application prospects in oilfield fracturing fluid and enhanced recovery ratio.)

1. The hydrophobic association polymer and the preparation method thereof are characterized in that the hydrophobic association polymer has the following structural general formula:

wherein a, b, c, d and e are the percentage of the structural units, b is 70-99.5%, c is 0.2-10%, a is 0.0.01-8%, d is 0.1-5%, and e is 0.1-6%.

2. The hydrophobically associative polymer according to claim 1 and the method of synthesizing the same, which comprises the steps of, in order:

(1) dissolving 0.05mol of beta-cyclodextrin and 0.05mol of maleic anhydride in N, N-dimethylformamide, and reacting at 80 ℃ for 10 hours to obtain a monomer MAH-beta-CD;

(2) adding 0.1mol of N, N-didodecylamine and 6N sodium hydroxide (50ml) into dichloromethane in an ice bath, introducing dry nitrogen, slowly adding methacryloyl chloride (0.104mol) into a mixed solution of dichloromethane by using a constant-pressure funnel, stirring for 2 hours, separating, washing an organic phase to be neutral by using distilled water, drying, and performing rotary evaporation to obtain a monomer DiC₁₂AM；

(3) MAH with the mole fraction of 0.1-5 percent-beta-CD and a mole fraction of 0.1 to 6% DiC₁₂And (2) adding AM, acrylamide with the molar fraction of 70-99.5%, acrylic acid with the molar fraction of 0.01-8% and 2-acrylamido-2-methylpropanesulfonic acid with the molar fraction of 0.2-10% into deionized water to prepare an aqueous solution with the monomer concentration of 10-20%, introducing nitrogen for half an hour, heating to 45-60 ℃, adding an initiator, and carrying out polymerization reaction for 6-8 hours to obtain the polymer.

3. The high-temperature-resistant fracturing fluid prepared by using the hydrophobic association polymer thickener of claim 1 comprises the following components in percentage by mass: 0.5-1% of hydrophobic association polymer thickening agent, and the balance of water.

Technical Field

The invention relates to an oil field fracturing fluid and a hydrophobic association polymer thickening agent for improving recovery ratio, a preparation method thereof and a high-temperature-resistant fracturing fluid.

Background

Since the 40's of the 20 th century, the birth, development and continued use of fracturing fluids have led to the formation of a discipline involving multiple systems. The current fracturing fluid thickeners used at home and abroad are mainly vegetable gums and derivatives thereof, viscoelastic surfactants (VES) and synthetic polymers. The thickening effect of the vegetable gum and the derivatives thereof is good, but the vegetable gum contains more water-insoluble vegetable fibers, and a large amount of residues after gum breaking can block fracturing cracks to directly influence the fracturing effect; the performance of the vegetable gum after chemical modification is improved, but the cost is difficult to control under the condition that the price of the vegetable gum is not stable. The VES fracturing liquid system does not contain water-insoluble substances, is simple in gel breaking and free of residues, and has the advantages of simple system preparation method, no other chemical additives and simplicity in construction, but the system is large in dosage of the viscoelastic surfactant and high in cost, and application of the system in oil fields is limited.

The synthetic polymer does not contain water-insoluble substances, has good viscoelasticity and thixotropy and low dosage, and has great development space. The hydrophobic association polymer is a water-soluble polymer with a small amount of hydrophobic functional monomers on the molecular chain of the polymer. Due to the introduction of a small amount of hydrophobic monomers, in a polymer solution, the hydrophobic monomers are subjected to association, so that polymer molecules are aggregated to form a supermolecular structure, and the supermolecular structure shows special rheological properties and has good temperature resistance, salt resistance and shear resistance, so that the supermolecular structure is widely concerned and widely applied to oil fields.

The self-assembly of hydrophobically associating polymers to form supramolecular aggregates can greatly increase the viscosity of the solution. The association polymer forms supermolecule aggregate with a critical association concentration, and when the solution concentration is lower than the critical association concentration, the association polymer takes intramolecular association as main component, and the viscosity is lower. When the concentration of the solution exceeds the critical association concentration, intermolecular association of the associative polymers occurs to form supramolecular aggregates.

Disclosure of Invention

The purpose of the invention is as follows: in order to improve the association performance of the hydrophobic association polymer and reduce the using amount of the polymer, the hydrophobic association polymer with a long hydrophobic carbon chain and the preparation method thereof are provided, and the polymer thickener has good water solubility, thickening property, viscoelasticity and shear thinning property, and also has temperature resistance and shear resistance.

The invention also aims to provide a preparation method of the hydrophobic polymer thickener, which has the advantages of reliable principle, simple and convenient operation, mild reaction conditions, easy control and high product yield.

The invention also aims to provide the high-temperature-resistant fracturing fluid prepared by using the hydrophobic polymer thickener, which has strong thickening property, stability, temperature resistance and salt resistance, is expected to be used for fracturing and acidizing of oil and gas fields, and has wide market prospect.

The technical scheme of the invention is realized as follows: a hydrophobically associating polymer having the following structure:

wherein a, b, c, d and e are the percentage of the structural units, b is 70-99.5%, c is 0.2-10%, a is 0.1-8%, d is 0.1-5%, and e is 0.1-6%.

The hydrophobic association polymer and the synthesis method thereof are characterized by sequentially comprising the following steps:

(1) dissolving 0.05mol of beta-cyclodextrin and 0.05mol of maleic anhydride in N, N-dimethylformamide, and reacting at 80 ℃ for 10 hours to obtain a monomer MAH-beta-CD;

(2) adding 0.1mol of N, N-didodecylamine and 6N sodium hydroxide (50ml) into dichloromethane in an ice bath, introducing dry nitrogen, slowly adding methacryloyl chloride (0.104mol) into the mixed solution of dichloromethane with a constant pressure funnel, stirring for 2 hours, separating, and addingWashing the organic phase with distilled water to neutrality, drying and rotary evaporating to obtain monomer DiC₁₂AM；

(3) MAH-beta-CD with the mole fraction of 0.1-5 percent and DiC with the mole fraction of 0.1-6 percent₁₂And adding the AM, acrylamide with the molar fraction of 70-99.5%, acrylic acid with the molar fraction of 0.01-8% and 2-acrylamido-2-methylpropanesulfonic acid with the molar fraction of 0.2-10% into deionized water to prepare an aqueous solution with the monomer concentration of 10-20%, introducing nitrogen for half an hour, heating to 45-60 ℃, adding an initiator, and carrying out polymerization reaction for 6-8 hours to obtain the polymer.

The high-temperature-resistant fracturing fluid prepared by using the hydrophobic polymer thickener comprises the following components in percentage by mass: 0.4-0.6% of hydrophobic association polymer thickening agent, and the balance of water

The invention provides a hydrophobic association polymer, a preparation method thereof and a method for preparing high-temperature-resistant fracturing fluid by using the hydrophobic association polymer, and the prepared fracturing fluid can keep excellent viscoelasticity at the temperature of below 100 ℃, and can be used for yield-increasing transformation of fracturing fluid of a medium-low permeability reservoir.

The invention has the beneficial effects that:

(1) the present invention relates to a process for the synthesis of hydrophobically associating polymers comprising cyclodextrin groups;

(2) the target cyclodextrin cavity structure can form a host-guest structure with a hydrophobic long chain, and has high temperature resistance and excellent viscoelasticity;

(3) the consumption of the hydrophobic association polymer is small, and the relative cost is low;

(4) clean fracturing fluid prepared by hydrophobic association polymer thickener at 100 ℃ for 170s^-1Shearing for 100min under the condition, keeping the viscosity above 200 mPas, and having good temperature resistance.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

FIG. 1 is a nuclear magnetic spectrum of the hydrophobically associating polymer thickener.

FIG. 2 is the rheological profile of a fracturing fluid formulated with 0.6% hydrophobically associative polymer in example one.

FIG. 3 is the rheological profile of a fracturing fluid formulated with 0.4% hydrophobically associative polymer in example one.

FIG. 4 is the rheological profile of a fracturing fluid formulated with 0.6% hydrophobically associative polymer in example two.

FIG. 5 is the rheological profile of a fracturing fluid formulated with 0.4% hydrophobically associative polymer in example two.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Preparation of hydrophobic association polymer thickener and high-temperature-resistant fracturing fluid