Oligomeric efficient clay stabilizer and preparation method thereof

Abstract

The invention discloses an oligomeric high-efficiency clay stabilizer and a preparation method of the oligomeric high-efficiency clay stabilizer, and the oligomeric high-efficiency clay stabilizer is mainly prepared from 20-40 wt% of an acrylamide monomer, 5-10 wt% of a DMDAAC monomer, 10-20 wt% of an AMPS monomer and 2-4 wt% of a methacryloyloxyalkyl trimethyl ammonium chloride monomer through a polymerization reaction. The prepared oligomeric efficient clay stabilizer has multiple functions of salt resistance, high temperature resistance and the like on the basis of the characteristics of efficient swelling resistance, scouring resistance and the like of the clay stabilizer, and the limitation of the clay stabilizer in complex reservoirs is broken through.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas field exploitation, relates to an oligomeric high-efficiency clay stabilizer, and also relates to a preparation method of the oligomeric high-efficiency clay stabilizer. Background Art

[0002] During the exploitation of oil and gas fields, it is necessary to inject a variety of working fluids into the formation, such as drilling fluid, perforating fluid, fracturing fluid, water injection fluid, etc. When clay minerals such as montmorillonite, illite and kaolinite in the reservoir come into contact with foreign liquids, they will hydrate, swell and disperse and migrate, blocking the reservoir pores, reducing the reservoir permeability and causing reservoir damage.

[0003] my country's oil fields generally have the characteristics of high formation temperature, high formation water mineralization, and high clay content. Conventional clay stabilizers have single performance and cannot meet the needs of complex reservoir exploration and development. There is an urgent need for a low-molecular-weight and high-efficiency clay stabilizer to supplement the shortcomings of existing clay stabilizers. Currently, commonly used clay stabilizers are divided into two categories: inorganic clay stabilizers and organic clay stabilizers; conventional inorganic salts (KCl, ZrOCl 2 etc.) are the earliest clay stabilizers used due to their low price, sufficient supply and obvious anti-swelling effect. However, they have obvious defects such as poor durability, poor scouring resistance, poor acid and alkali resistance, and lack anti-migration ability, which has great limitations. Quaternary ammonium salts and pyridinium salts cationic surfactants have strong adsorption force with the negative charge on the clay surface, are resistant to scouring, and are long-lasting, but their lipophilic groups make the reservoir lipophilic, causing the clay to oil and swell. The cationic properties of themselves can react with some anions to produce precipitation and block the reservoir, so they need to be carefully selected when used. Organic cationic polymer clay stabilizers have a large molecular weight and carry multiple hydrophobic chains and hydrophilic cationic groups. They can be firmly adsorbed on the clay surface through intermolecular hydrogen bonds and other effects to prevent the hydration, expansion and dispersion migration of clay minerals in the reservoir. They have the advantages of small dosage, high efficiency and irreversible adsorption.

[0004] The Chinese patent "A Multifunctional Clay Stabilizer" (application date: 2017.02.07; application number: CN201710067555.1; announcement date: 2017.05.31; publication number: CN106753316A) discloses a multifunctional clay stabilizer, which is made by reacting allyl chloride, dimethylamine and AMPS as monomer raw materials. It has a highly efficient anti-swelling effect and also has a drainage function, but is not resistant to high temperatures.

[0005] Chinese patent "A method for preparing a low molecular weight clay stabilizer" (application date: 20140408; application number: CN201310118314.7; announcement date 20141015; publication number: CN104098738A) discloses a multifunctional clay stabilizer, which uses two monomers, ammonium salt containing carbon-carbon double bonds and AMPS, to synthesize a polymer clay stabilizer with a molecular weight of less than 50,000. The temperature resistance reaches 120°C, but its maximum anti-swelling rate is 76.8%, and the anti-swelling effect is average. Summary of the invention

[0006] The purpose of the present invention is to provide a method for preparing an oligomeric high-efficiency clay stabilizer, which solves the problem that the existing clay stabilizers have single performance and cannot meet the needs of complex reservoir exploration and development.

[0007] A technical solution adopted by the present invention is a low-molecular-weight high-efficiency clay stabilizer having a chemical structural formula of:

[0008]

[0009] Among them, m:n:x:y is the percentage of structural units, m is 50-60%, n is 10-20%, x is 20-30%, y is 5-10%; z is the number of carbon atoms in the alkyl chain, z is 5-8.

[0010] The present invention is also characterized in that:

[0011] The molecular weight of low-molecular-weight high-efficiency clay stabilizer is between 30,000 and 60,000.

[0012] Another technical solution adopted by the present invention is a method for preparing an oligomeric high-efficiency clay stabilizer, which is specifically implemented according to the following steps:

[0013] Step 1, placing acrylamide monomer and AMPS monomer in a round-bottom flask, adding water, and adjusting the pH of the system to neutral using NaOH solution during stirring;

[0014] Step 2, adding methacryloyloxyalkyltrimethylammonium chloride and DMDAAC to the solution prepared in step 1 and stirring;

[0015] Step 3, heating the reactants in step 2 to 400°C-100°C under nitrogen protection, adding an initiator dropwise to the reactants and stirring them thoroughly;

[0016] Step 4, placing the product obtained in step 3 at a constant temperature for reaction for 5h-10h. After the reaction is completed, the solution is filtered out to obtain a crude product, which is repeatedly washed with ethanol for 3-5 times, and then soaked in acetone for 1h-3h. After drying, a white compound is obtained, that is, a low-molecular-weight high-efficiency clay stabilizer.

[0017] The present invention is also characterized in that:

[0018] Step 1: Weigh 20-40 wt% of acrylamide monomer and 10-20 wt% of AMPS monomer.

[0019] Step 2: Weigh 5-10 wt% of dimethyldiallyl ammonium chloride monomer and 2-4 wt% of methacryloyloxyalkyltrimethylammonium chloride monomer.

[0020] In step 2, the alkyl group of methacryloyloxyalkyltrimethylammonium chloride contains 5 to 8 carbon atoms.

[0021] In step 3, the initiator is one of sodium bisulfite, ammonium persulfate or potassium persulfate, or any two of them, or a combination of any two or more of them.

[0022] The beneficial effects of the present invention are as follows: the present invention prepares a low-molecular-weight high-efficiency clay stabilizer, each component has good compatibility, and on the basis of the high-efficiency anti-swelling and erosion-resistant properties of the clay stabilizer, it also has multiple functions such as salt resistance and high temperature resistance. It is a multifunctional quaternary low-molecular-weight clay stabilizer, which breaks through the limitations of clay stabilizers in complex reservoirs and has broad development and application prospects. DETAILED DESCRIPTION

[0023] The present invention is described in detail below in conjunction with specific implementation modes.

[0024] The chemical structural formula of the oligomeric high-efficiency clay stabilizer of the present invention is:

[0025]

[0026] Wherein, m:n:x:y is the percentage of structural units, m is 50-60%, n is 10-20%, x is 20-30%, y is 5-10%; z is the number of carbon atoms in the alkyl chain, z is 5 to 8;

[0027] The molecular weight of low-molecular-weight high-efficiency clay stabilizer is 30,000-60,000;

[0028] The preparation method of the oligomeric high-efficiency clay stabilizer of the present invention is specifically implemented according to the following steps:

[0029] Step 1, placing acrylamide monomer and AMPS monomer in a round-bottom flask, adding water, and adjusting the pH of the system to neutral using NaOH solution during stirring;

[0030] Weigh 20-40 wt% of acrylamide monomer and 10-20 wt% of AMPS monomer.

[0031] Step 2, adding methacryloyloxyalkyltrimethylammonium chloride and DMDAAC to the solution prepared in step 1 and stirring;

[0032] Weigh 5-10 wt% of DMDAAC (dimethyldiallyl ammonium chloride) monomer and 2-4 wt% of methacryloyloxyalkyltrimethylammonium chloride monomer, wherein the alkyl group of methacryloyloxyalkyltrimethylammonium chloride has 5-8 carbon atoms;

[0033] Step 3, heating the reactants in step 2 to 40°C-100°C under nitrogen protection, adding an initiator dropwise to the reactants and stirring them thoroughly;

[0034] The initiator is one of sodium bisulfite, ammonium persulfate or potassium persulfate, or any two of them, or a combination of any two or more of them;

[0035] Step 4, placing the product obtained in step 3 at a constant temperature for reaction for 5h-10h. After the reaction is completed, the solution is filtered out to obtain a crude product, which is repeatedly washed with ethanol for 3-5 times, and then soaked in acetone for 1h-3h. After drying, a white compound is obtained, that is, a low-molecular-weight high-efficiency clay stabilizer.

[0036] The low-molecular-weight high-efficiency clay stabilizer of the present invention is used for complex reservoirs such as deep wells and high temperatures.

[0037] The invention discloses a method for preparing an oligomeric high-efficiency clay stabilizer. The quaternary ammonium salt organic cation in the polymer molecule enhances the acid and alkali resistance of the clay stabilizer, and the group has strong adsorption to the surface of the clay mineral and is resistant to scouring. A strong hydrophobic non-polar long-chain functional group is introduced to wrap the clay mineral, making it difficult for water molecules to contact the surface of the clay mineral. The polymer molecule contains a plurality of long-chain molecules, which can be adsorbed between crystal layers of the clay mineral to prevent dispersion and particle migration. The AMPS group is introduced to improve the temperature and salt resistance of the quaternary oligomeric compound.

[0038] Example 1

[0039] The preparation method of the oligomeric high-efficiency clay stabilizer of the present invention is specifically implemented according to the following steps:

[0040] Step 1, adding 20 wt% acrylamide and 10 wt% AMPS into a 500 ml three-necked flask, adding 200 ml distilled water, and adjusting the pH of the solution to neutral using 2.0 M sodium hydroxide solution during stirring;

[0041] Step 2, weighing 2 wt% of methacryloyloxypentyltrimethylammonium chloride and 5 wt% of DMDAAC (dimethyldiallylammonium chloride), adding them to the above solution and stirring;

[0042] Step 3: Heat to 40°C under nitrogen protection and add 2.5×10 -3 mol of sodium bisulfite aqueous solution and stir thoroughly;

[0043] Step 4, placing the product obtained in step 3 at a constant temperature for reaction for 5 hours. After the reaction is completed, the solution is filtered out to obtain a crude product, which is repeatedly washed with ethanol for 3 times, then soaked in acetone for 1 hour, and dried to obtain a white compound, that is, a low-polymer high-efficiency clay stabilizer.

[0044] Example 2

[0045] The preparation method of the oligomeric high-efficiency clay stabilizer of the present invention is specifically implemented according to the following steps:

[0046] Step 1, adding 30 wt% acrylamide and 15 wt% AMPS into a 500 ml three-necked flask, adding 200 ml distilled water, and adjusting the pH of the solution to neutral using 2.0 M sodium hydroxide solution during stirring;

[0047] Step 2, weighing 3 wt% of methacryloyloxypentyltrimethylammonium chloride and 7.5 wt% of DMDAAC (dimethyldiallylammonium chloride), adding them to the above solution and stirring;

[0048] Step 3: Heat to 50°C under nitrogen protection, and add 3.5×10 -3 mol of ammonium persulfate aqueous solution and stir thoroughly;

[0049] Step 4, placing the product obtained in step 3 at a constant temperature for reaction for 6 hours. After the reaction is completed, the solution is filtered out to obtain a crude product, which is repeatedly washed with ethanol for 3 times, then soaked in acetone for 2 hours, and dried to obtain a white compound, that is, a low-molecular-weight high-efficiency clay stabilizer.

[0050] Example 3

[0051] The preparation method of the oligomeric high-efficiency clay stabilizer of the present invention is specifically implemented according to the following steps:

[0052] Step 1, adding 40 wt% acrylamide and 20 wt% AMPS into a 500 ml three-necked flask, adding 200 ml of distilled water, and adjusting the pH of the solution to neutral with 2.0 M sodium hydroxide solution during stirring;

[0053] Step 2, weighing 4 wt% of methacryloyloxypentyltrimethylammonium chloride and 10 wt% of DMDAAC (dimethyldiallylammonium chloride), adding them to the above solution and stirring;

[0054] Step 3: Heat to 60°C under nitrogen protection and add 5×10 -3 mol of potassium persulfate aqueous solution and stir thoroughly;

[0055] Step 4, react at a constant temperature for 7 hours. After the reaction is completed, filter out the solution to obtain a crude product, wash it repeatedly with ethanol for 3 times, soak it in acetone for 2 hours, and dry it to obtain a white compound, that is, a low-molecular-weight high-efficiency clay stabilizer.

[0056] Example 4

[0057] The preparation method of the oligomeric high-efficiency clay stabilizer of the present invention is specifically implemented according to the following steps:

[0058] Step 1, adding 20 wt% acrylamide and 10 wt% AMPS into a 500 ml three-necked flask, adding 200 ml distilled water, and adjusting the pH of the solution to neutral using 2.0 M sodium hydroxide solution during stirring;

[0059] Step 2, weighing 2 wt% of methacryloyloxyhexyltrimethylammonium chloride and 5 wt% of DMDAAC (dimethyldiallylammonium chloride), adding them to the above solution and stirring;

[0060] Step 3: Heat to 60°C under nitrogen protection and add 2.5×10 -3 mol of ammonium persulfate and sodium bisulfite (molar mass ratio is 1:1) in aqueous solution and stir thoroughly;

[0061] Step 4, react at a constant temperature for 8 hours. After the reaction is completed, filter out the solution to obtain a crude product, wash it repeatedly with ethanol for 3 times, soak it in acetone for 2 hours, and dry it to obtain a white compound, that is, a low-molecular-weight high-efficiency clay stabilizer.

[0062] Example 5

[0063] The preparation method of the oligomeric high-efficiency clay stabilizer of the present invention is specifically implemented according to the following steps:

[0064] Step 1, adding 20 wt% acrylamide and 10 wt% AMPS into a 500 ml three-necked flask, adding 200 ml distilled water, and adjusting the pH of the solution to neutral using 2.0 M sodium hydroxide solution during stirring;

[0065] Step 2, weighing 2 wt% of methacryloyloxyheptyltrimethylammonium chloride and 5 wt% of DMDAAC (dimethyldiallylammonium chloride), adding them to the above solution and stirring;

[0066] Step 3: Heat to 60°C under nitrogen protection and add 2.5×10 -3 mol of sodium bisulfite and potassium sulfate (molar mass ratio is 1:1) in aqueous solution and stir thoroughly;

[0067] Step 4, react at a constant temperature for 8 hours. After the reaction is completed, filter out the solution to obtain a crude product, wash it repeatedly with ethanol for 3 times, soak it in acetone for 2 hours, and dry it to obtain a white compound, that is, a low-molecular-weight high-efficiency clay stabilizer.

[0068] Example 6

[0069] The preparation method of the oligomeric high-efficiency clay stabilizer of the present invention is specifically implemented according to the following steps:

[0070] Step 1, adding 20 wt% acrylamide and 10 wt% AMPS into a 500 ml three-necked flask, adding 200 ml distilled water, and adjusting the pH of the solution to neutral using 2.0 M sodium hydroxide solution during stirring;

[0071] Step 2, weighing 2 wt% of methacryloyloxyoctyltrimethylammonium chloride and 5 wt% of DMDAAC (dimethyldiallylammonium chloride), adding them to the above solution and stirring;

[0072] Step 3: Heat to 100°C under nitrogen protection and add 2.5×10 -3 mol of potassium sulfate and ammonium persulfate (molar mass ratio is 1:1) in aqueous solution and stir thoroughly;

[0073] Step 4, react at a constant temperature for 10 hours. After the reaction is completed, filter out the solution to obtain a crude product, wash it repeatedly with ethanol for 5 times, soak it in acetone for 3 hours, and dry it to obtain a white compound, that is, a low-molecular-weight high-efficiency clay stabilizer.

[0074] Example 7

[0075] The preparation method of the oligomeric high-efficiency clay stabilizer of the present invention is specifically implemented according to the following steps:

[0076] Step 1, adding 40 wt% acrylamide and 20 wt% AMPS into a 500 ml three-necked flask, adding 200 ml of distilled water, and adjusting the pH of the solution to neutral with 2.0 M sodium hydroxide solution during stirring;

[0077] Step 2, weighing 4 wt% of methacryloyloxypentyltrimethylammonium chloride and 10 wt% of DMDAAC (dimethyldiallylammonium chloride), adding them to the above solution and stirring;

[0078] Step 3: Heat to 100°C under nitrogen protection and add 2.5×10 -3 mol of sodium bisulfite, ammonium persulfate or potassium persulfate (molar mass ratio of 1:1:1) in aqueous solution and stir thoroughly;

[0079] Step 4, react at a constant temperature for 10 hours. After the reaction is completed, filter out the solution to obtain a crude product, wash it repeatedly with ethanol for 5 times, soak it in acetone for 3 hours, and dry it to obtain a white compound, that is, a low-molecular-weight high-efficiency clay stabilizer.

[0080] The anti-swelling performance of the above six embodiments was evaluated according to "SY / T5971-94 Performance Evaluation Method for Clay Stabilizer for Water Injection", and the water washability was evaluated at room temperature according to the enterprise standard "Q / SH 0053-2010 Technical Requirements for Clay Stabilizers". The experimental results are shown in Table 1.

[0081] Table 1 Dissolution rate of core powder in Examples 1-7

[0082] Test samples Anti-swelling rate (%) Temperature resistance(℃) Washing resistance (%) Example 1 89.2 151 93 Example 2 87.8 148 92 Example 3 86.4 154 94 Example 4 88.5 150 94 Example 5 94.2 158 95 Example 6 93.9 157 93 Example 7 94 155 95

[0083] The test results show that the oligomeric high-efficiency clay stabilizers prepared in Examples 1-7 are all highly effective in preventing swelling and are resistant to heat and water washing.

[0084] The preparation method of the low-molecular-weight high-efficiency clay stabilizer of the present invention comprises 20-40wt% of acrylamide monomer, 5-10wt% of DMDAAC monomer, 10-20wt% of AMPS monomer and 2-4wt% of methacryloyloxyalkyl trimethylammonium chloride monomer through polymerization reaction. The present invention overcomes the problem that the existing clay stabilizer has single performance and cannot meet the needs of complex reservoir exploration and development. The low-molecular-weight high-efficiency clay stabilizer prepared by the present invention has high-efficiency anti-swelling effect and high-temperature resistance, and the stability of the stabilizer is significantly improved. The low-molecular-weight high-efficiency clay stabilizer prepared by the present invention has low cost and simple preparation process, and can reduce engineering cost and improve economic and social benefits.

Claims

1. Low-molecular-weight high-efficiency clay stabilizer, characterized in that: The chemical structure is: Among them, m:n:x:y is the percentage of structural units, m is 50-60%, n is 10-20%, x is 20-30%, y is 5-10%; z is the number of carbon atoms in the alkyl chain, z is 5-8.

2. The oligomeric high-efficiency clay stabilizer according to claim 1, characterized in that: The molecular weight of the oligomeric high-efficiency clay stabilizer is 30,000-60,000.

3. A method for preparing an oligomeric high-efficiency clay stabilizer, characterized in that: Follow the steps below to implement it: Step 1, placing acrylamide monomer and AMPS monomer in a round-bottom flask, adding water, and adjusting the pH of the system to neutral using NaOH solution during stirring; Step 2, adding methacryloyloxyalkyltrimethylammonium chloride and DMDAAC to the solution prepared in step 1 and stirring; Step 3, heating the reactants in step 2 to 40°C-100°C under nitrogen protection, adding an initiator dropwise to the reactants and stirring them thoroughly; Step 4, placing the product obtained in step 3 at a constant temperature for reaction for 5h-10h. After the reaction is completed, the solution is filtered out to obtain a crude product, which is repeatedly washed with ethanol for 3-5 times, and then soaked in acetone for 1h-3h. After drying, a white compound is obtained, that is, a low-molecular-weight high-efficiency clay stabilizer.

4. The method for preparing the oligomeric high-efficiency clay stabilizer according to claim 3, characterized in that: In the step 1, 20-40 wt% of acrylamide monomer and 10-20 wt% of AMPS monomer are weighed.

5. The method for preparing the oligomeric high-efficiency clay stabilizer according to claim 3, characterized in that: In the step 2, 5-10 wt% of DMDAAC monomer and 2-4 wt% of methacryloyloxyalkyltrimethylammonium chloride monomer are weighed.

6. The method for preparing the oligomeric high-efficiency clay stabilizer according to claim 3, characterized in that: In the step 2, the alkyl group of the methacryloyloxyalkyltrimethylammonium chloride contains 5 to 8 carbon atoms.

7. The method for preparing the oligomeric high-efficiency clay stabilizer according to claim 3, characterized in that: In step 3, the initiator is one of sodium bisulfite, ammonium persulfate or potassium persulfate, or any two of them, or a combination of any two or more of them.

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