Oligomeric high-efficiency clay stabilizer and method for preparing the same

Abstract

The application discloses an oligomerized high-efficiency clay stabilizer, and discloses a preparation method of the oligomerized high-efficiency clay stabilizer. The oligomerized high-efficiency clay stabilizer is prepared by polymerization reaction of 20-40wt% acrylamide monomers, 5-10wt% DMDAAC monomers, 10-20wt% AMPS monomers and 2-4wt% methacryloyloxyalkyl trimethylammonium chloride monomers. The oligomerized high-efficiency clay stabilizer prepared by the application has the functions of salt resistance and high-temperature resistance in addition to the characteristics of high-efficiency anti-swelling and erosion resistance of the clay stabilizer, and breaks the limitation of the clay stabilizer in complex reservoirs.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of oil and gas field exploitation, and relates to an oligomeric efficient clay stabilizer and a preparation method of the oligomeric efficient clay stabilizer. BACKGROUND

[0002] In the process of oil and gas field exploitation, various working fluids such as drilling fluid, perforating fluid, fracturing fluid and water injection fluid need to be injected into the formation. When the montmorillonite, illite and kaolinite and other clay minerals in the reservoir are in contact with the external liquid, they will undergo hydration swelling and dispersion migration, block the reservoir pores, reduce the reservoir permeability and cause reservoir damage.

[0003] In China, oil fields are generally characterized by high formation temperature, high formation water salinity and high clay content. Conventional clay stabilizers have single performance and cannot meet the needs of complex reservoir exploration and development, so an oligomeric efficient clay stabilizer is needed to make up for the shortcomings of existing clay stabilizers. Currently, clay stabilizers are divided into two categories: inorganic clay stabilizers and organic clay stabilizers. Conventional inorganic salt (KCl, ZrOCl2, etc.) is the earliest used clay stabilizer due to its low price, abundant supply, obvious anti-swelling effect, but it has obvious defects such as poor durability, poor erosion resistance, poor acid and alkali resistance and no anti-migration ability, which has great limitations. Quaternary ammonium salt, pyridine salt cationic surfactant has strong adsorption force with the negative charge on the surface of clay, good erosion resistance and long-term durability, but its lipophilic group makes the reservoir become lipophilic, leading to clay oil swelling, and the nature of its own cation can react with some anions to produce sedimentation and block the reservoir, so it needs to be carefully selected when used. Organic cationic polymer clay stabilizer has large molecular weight and multiple hydrophobic chains and hydrophilic cationic groups, which can be firmly adsorbed on the surface of clay through intermolecular hydrogen bonds and other actions, preventing the hydration swelling and dispersion migration of clay minerals in the reservoir, and has the advantages of small dosage, high efficiency and irreversible adsorption.

[0004] Chinese patent "Multifunctional clay stabilizer" (application date: February 7, 2017; application number: CN201710067555.1; publication date: May 31, 2017; publication number: CN106753316A) discloses a multifunctional clay stabilizer, which is prepared by using allyl chloride, dimethylamine and AMPS as monomer raw materials, has high anti-swelling effect, and has the function of assisting drainage, but is not resistant to high temperature.

[0005] CN104098738A discloses a multifunctional clay stabilizer, which is synthesized by using an ammonium salt containing a carbon-carbon double bond and AMPS two monomers to obtain a polymer clay stabilizer with a molecular weight of less than 50,000, and the temperature resistance reaches 120 DEG C, but the maximum anti-swelling rate is 76.8%, and the anti-swelling effect is general. SUMMARY

[0006] The purpose of the present application is to provide a preparation method of an oligomer high-efficiency clay stabilizer, which solves the problem that the existing clay stabilizer has single performance and cannot meet the complex reservoir exploration and development requirements.

[0007] One technical solution adopted by the present application is an oligomer high-efficiency clay stabilizer, and the chemical structural formula is as follows:

[0008]

[0009] In the formula, m:n:x:y are structural unit percentages, m is 50-60%, n is 10-20%, x is 20-30%, and y is 5-10%; z is the number of carbon atoms in the alkyl chain, and z is 5-8.

[0010] The present application is also characterized in that,

[0011] The molecular weight of the oligomer high-efficiency clay stabilizer is 30,000-60,000.

[0012] Another technical solution adopted by the present application is a preparation method of an oligomer high-efficiency clay stabilizer, which is implemented according to the following steps:

[0013] Step 1, acrylamide monomer and AMPS monomer are placed in a round-bottom flask, water is added, and NaOH solution is used to adjust the system pH to neutral during stirring;

[0014] Step 2, methyl methacryloyloxyalkyl trimethyl ammonium chloride and DMDAAC are added to the solution prepared in step 1 and stirred;

[0015] Step 3, the reactants in step 2 are placed in nitrogen protection and heated to 400 DEG C-100 DEG C, an initiator is added dropwise to the reactants, and the reactants are fully stirred;

[0016] Step 4, the product prepared in step 3 is placed in a constant-temperature environment and reacted for 5-10 hours, after the reaction is completed, the solution is filtered off, the crude product is repeatedly washed with ethanol for 3-5 times, then the crude product is soaked in acetone for 1-3 hours, and the white compound is obtained after drying, that is, the oligomer high-efficiency clay stabilizer is obtained.

[0017] The present application is also characterized in that,

[0018] Step 1, weigh 20-40wt% of acrylamide monomer, 10-20wt% of AMPS monomer.

[0019] Step 2, weigh 5-10wt% of dimethyl diallyl ammonium chloride monomer, 2-4wt% of methacryloyloxyalkyl trimethyl ammonium chloride monomer.

[0020] The number of carbon atoms in the alkyl group of the methacryloyloxyalkyl trimethyl ammonium chloride in step 2 is 5-8.

[0021] The initiator in step 3 is one of sodium bisulfite, ammonium persulfate or potassium persulfate, or a combination of any two or more thereof.

[0022] The beneficial effects of the present application are: the present application prepares an oligomeric high-efficiency clay stabilizer, and the components have good compatibility, and on the basis of the high-efficiency anti-swelling and erosion resistance of the clay stabilizer, it has multiple functions such as salt resistance and high temperature resistance, is a multifunctional four-component oligomeric clay stabilizer, breaks through the limitations of clay stabilizers in complex reservoirs, and has a broad development and application prospect. DETAILED DESCRIPTION

[0023] The present application will be described in detail below in combination with specific embodiments.

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

[0025]

[0026] Among them, m:n:x:y is the percentage of the structural unit, 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;

[0027] The molecular weight of the oligomeric high-efficiency clay stabilizer is 30000-60000;

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

[0029] Step 1, the acrylamide monomer and the AMPS monomer are placed in a round-bottom flask, water is added, and the system PH is adjusted to neutral during stirring using NaOH solution;

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

[0031] Step 2, add methacryloyloxyalkyl trimethyl ammonium chloride and DMDAAC to the solution prepared in step 1 and stir;

[0032] weighing 5-10wt% of DMDAAC (dimethyl diallyl ammonium chloride) monomer, 2-4wt% of methacryloyloxyalkyl trimethyl ammonium chloride monomer, the alkyl in the methacryloyloxyalkyl trimethyl ammonium chloride monomer contains 5-8 carbon atoms;

[0033] Step 3, the reactants in step 2 are placed under nitrogen protection and heated to 40-100 DEG C, an initiator is added dropwise to the reactants and fully stirred;

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

[0035] Step 4, the product prepared in step 3 is placed under constant temperature for 5-10h, the reaction is completed, the solution is filtered off, the crude product is repeatedly washed with ethanol for 3-5 times, then soaked in acetone for 1-3h, and dried to obtain a white compound, i.e. the oligomer high-efficiency clay stabilizer.

[0036] The oligomer high-efficiency clay stabilizer is used in complex reservoirs such as deep well high temperature reservoirs.

[0037] The preparation method of the oligomer high-efficiency clay stabilizer, the quaternary ammonium salt organic cation in the polymer molecule enhances the acid and alkali resistance of the clay stabilizer, meanwhile, the group has strong adsorption on the surface of clay minerals and is resistant to washing; the strong hydrophobic non-polar long-chain functional groups are introduced to wrap the clay minerals, so that water molecules are difficult to contact the surface of the clay minerals; the polymer molecule contains multiple long-chain molecules, which can be adsorbed between the clay mineral crystal layers to prevent dispersion and particle migration; the AMPS group is introduced to improve the temperature and salt resistance of the quaternary oligomer compound.

[0038] Example 1

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

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

[0041] Step 2, 2wt% of methacryloyloxy pentyl trimethyl ammonium chloride and 5wt% of DMDAAC (dimethyl diallyl ammonium chloride) are weighed and added to the above solution for stirring;

[0042] Step 3, under nitrogen protection, the temperature is raised to 40 DEG C, 2.5x10 -3 mol of sodium bisulfite aqueous solution is added dropwise to the reaction, and fully stirred;

[0043] Step 4, the product prepared in step 3 is placed in a constant temperature for 5h, the reaction is completed, the solution is filtered out, the crude product is obtained, washed with ethanol for 3 times, soaked in acetone for 1h, dried to obtain a white compound, and the oligomerization high-efficiency clay stabilizer is obtained.

[0044] Example 2

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

[0046] Step 1, 30wt% acrylamide and 15wt% AMPS are added to a 500ml three-necked bottle, 200ml distilled water is added, and a 2.0M sodium hydroxide solution is used to adjust the pH of the solution to neutral during stirring;

[0047] Step 2, 3wt% methacryloyloxy pentyl trimethyl ammonium chloride and 7.5wt% DMDAAC (dimethyl diallyl ammonium chloride) are weighed and added to the above solution for stirring;

[0048] Step 3, under the protection of nitrogen, the temperature is raised to 50℃, 3.5×10 -3 mol of ammonium persulfate aqueous solution is added dropwise into the reaction, and fully stirred;

[0049] Step 4, the product prepared in step 3 is placed in a constant temperature for 6h, the reaction is completed, the solution is filtered out, the crude product is obtained, washed with ethanol for 3 times, soaked in acetone for 2h, dried to obtain a white compound, and the oligomerization high-efficiency clay stabilizer is obtained.

[0050] Example 3

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

[0052] Step 1, 40wt% acrylamide and 20wt% AMPS are added to a 500ml three-necked bottle, 200ml distilled water is added, and a 2.0M sodium hydroxide solution is used to adjust the pH of the solution to neutral during stirring;

[0053] Step 2, 4wt% methacryloyloxy pentyl trimethyl ammonium chloride and 10wt% DMDAAC (dimethyl diallyl ammonium chloride) are weighed and added to the above solution for stirring;

[0054] Step 3, under the protection of nitrogen, the temperature is raised to 60℃, 5×10 -3 mol of potassium persulfate aqueous solution is added dropwise into the reaction, and fully stirred;

[0055] Step 4, the reaction is carried out at constant temperature for 7h, the reaction is completed, the solution is filtered out, the crude product is obtained, washed with ethanol for 3 times, soaked in acetone for 2h, dried, and then a white compound is obtained, that is, the oligomer high-efficiency clay stabilizer.

[0056] Example 4

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

[0058] Step 1, 20wt% acrylamide and 10wt% AMPS are added into a 500ml three-necked bottle, 200ml distilled water is added, and a 2.0M sodium hydroxide solution is used to adjust the pH of the solution to neutral during stirring;

[0059] Step 2, 2wt% methacryloyloxyhexyl trimethyl ammonium chloride and 5wt% DMDAAC (dimethyl diallyl ammonium chloride) are weighed and added into the above solution for stirring;

[0060] Step 3, under the protection of nitrogen, the temperature is raised to 60℃, 2.5×10 -3 mol of an aqueous solution of ammonium persulfate and sodium bisulfite (molar mass ratio is 1:1) is added dropwise into the reaction, and fully stirred;

[0061] Step 4, the reaction is carried out at constant temperature for 8h, the reaction is completed, the solution is filtered out, the crude product is obtained, washed with ethanol for 3 times, soaked in acetone for 2h, dried, and then a white compound is obtained, that is, the oligomer high-efficiency clay stabilizer.

[0062] Example 5

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

[0064] Step 1, 20wt% acrylamide and 10wt% AMPS are added into a 500ml three-necked bottle, 200ml distilled water is added, and a 2.0M sodium hydroxide solution is used to adjust the pH of the solution to neutral during stirring;

[0065] Step 2, 2wt% methacryloyloxyhexyl trimethyl ammonium chloride and 5wt% DMDAAC (dimethyl diallyl ammonium chloride) are weighed and added into the above solution for stirring;

[0066] Step 3, under the protection of nitrogen, the temperature is raised to 60℃, 2.5×10 -3 mol of an aqueous solution of sodium bisulfite and potassium sulfate (molar mass ratio is 1:1) is added dropwise into the reaction, and fully stirred;

[0067] Step 4, the reaction is carried out at constant temperature for 8h, and after the reaction is completed, the solution is filtered out to obtain a crude product, which is repeatedly washed with ethanol for 3 times, soaked in acetone for 2h, dried, and then a white compound is obtained, that is, the oligomeric high-efficiency clay stabilizer.

[0068] Example 6

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

[0070] Step 1, 20wt% acrylamide and 10wt% AMPS are added to a 500ml three-necked bottle, 200ml distilled water is added, and a 2.0M sodium hydroxide solution is used to adjust the pH of the solution to neutral during stirring;

[0071] Step 2, 2wt% methacryloyloxyoctyl trimethyl ammonium chloride and 5wt% DMDAAC (dimethyl diallyl ammonium chloride) are weighed and added to the above solution for stirring;

[0072] Step 3, under the protection of nitrogen, the temperature is raised to 100℃, and 2.5×10 -3 mol of an aqueous solution of potassium sulfate and ammonium persulfate (molar mass ratio 1:1) is added dropwise to the reaction, and fully stirred;

[0073] Step 4, the reaction is carried out at constant temperature for 10h, and after the reaction is completed, the solution is filtered out to obtain a crude product, which is repeatedly washed with ethanol for 5 times, soaked in acetone for 3h, dried, and then a white compound is obtained, that is, the oligomeric high-efficiency clay stabilizer.

[0074] Example 7

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

[0076] Step 1, 40wt% acrylamide and 20wt% AMPS are added to a 500ml three-necked bottle, 200ml distilled water is added, and a 2.0M sodium hydroxide solution is used to adjust the pH of the solution to neutral during stirring;

[0077] Step 2, 4wt% methacryloyloxy pentyl trimethyl ammonium chloride and 10wt% DMDAAC (dimethyl diallyl ammonium chloride) are weighed and added to the above solution for stirring;

[0078] Step 3, under the protection of nitrogen, the temperature is raised to 100℃, and 2.5×10 -3 mol of an aqueous solution of sodium bisulfite, ammonium persulfate or potassium persulfate (molar mass ratio 1:1:1) is added dropwise to the reaction, and fully stirred;

[0079] Step 4, the reaction is carried out for 10 hours at constant temperature, the reaction is completed, the solution is filtered, the crude product is obtained, the crude product is repeatedly washed with ethanol for 5 times, the crude product is soaked in acetone for 3 hours, and the white compound is obtained after drying, so that the oligomer high-efficiency clay stabilizer is obtained.

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

[0081] Table 1: Dissolution rate of core powder of examples 1-7

[0082] Test sample Anti-bulking rate (%) Temperature resistance performance (°C) Washing resistance rate (%) 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 oligomer high-efficiency clay stabilizer prepared by examples 1-7 can effectively prevent swelling and has temperature resistance and water washing resistance.

[0084] The preparation method of the oligomer high-efficiency clay stabilizer comprises 20-40 wt% of acrylamide monomers, 5-10 wt% of DMDAAC monomers, 10-20 wt% of AMPS monomers and 2-4 wt% of methacryloyloxyalkyl trimethyl ammonium chloride monomers, which are prepared by polymerization. The oligomer high-efficiency clay stabilizer prepared by the method has high-efficiency anti-swelling effect, high-temperature resistance and high stability, and the cost is low. The preparation process is simple, the engineering cost is reduced, and the economic and social benefits are improved.

Claims

1. A low-polymer high-efficiency clay stabilizer, characterized in that, The chemical structural formula is: Where m:n:x:y represents the percentage of structural units, m is 50-60%, n is 10-20%, x is 20-30%, and y is 5-10%; z represents the number of carbon atoms in the alkyl chain, z is 5-8; The molecular weight of the oligomeric high-efficiency clay stabilizer is between 30,000 and 60,000.

2. A method for preparing an oligomeric high-efficiency clay stabilizer, characterized in that, The specific steps are as follows: Step 1: Place the acrylamide monomer and AMPS monomer in a round-bottom flask, add water, and adjust the pH of the system to neutral using NaOH solution while stirring. Step 2: Add methacryloyloxyalkyltrimethylammonium chloride and DMDAAC to the solution prepared in Step 1 and stir. Step 3: Place the reactants from Step 2 under nitrogen protection and heat to 40℃-100℃. Add the initiator dropwise to the reactants and stir thoroughly. Step 4: Place the product obtained in step 3 at a constant temperature for 5-10 hours. After the reaction is complete, filter out the solution to obtain a crude product. Wash it repeatedly with ethanol 3-5 times, then soak it in acetone for 1-3 hours. After drying, a white compound is obtained, which is the oligomeric high-efficiency clay stabilizer. The molecular weight of the oligomeric high-efficiency clay stabilizer is 30,000-60,000.

3. The preparation method of the oligomeric high-efficiency clay stabilizer according to claim 2, characterized in that, In step 1, 20-40 wt% acrylamide monomer and 10-20 wt% AMPS monomer are weighed.

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

5. The preparation method of the oligomeric high-efficiency clay stabilizer according to claim 2, characterized in that, In step 2, the alkyl group in methacryloyloxyalkyltrimethylammonium chloride has 5-8 carbon atoms.

6. The preparation method of the oligomeric high-efficiency clay stabilizer according to claim 2, characterized in that, In step 3, the initiator is one of sodium bisulfite, ammonium persulfate, or potassium persulfate, or any two or more of them.

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