A clay stabilizer for oil fields and its preparation method and application

Abstract

The present invention belongs to the field of oil production technology, and is specifically related to a kind of oil field clay stabilizer and its preparation method and application. The preparation method specifically comprises the following steps: adding dodecylamine, ethanol, allyl chloride in a reactor, passing nitrogen, heating, temperature control at 50-60°C, maintaining pH7-8; distilling under reduced pressure, sequentially adding 2-(allyldimethylsilyl) pyridine, 3-(methacrylamido) propyldimethyl (3-sulfopropyl) ammonium inner salt, 1-vinyl-3-ethylimidazolium bromide, potassium dihydrogen phosphate, deionized water, adjusting pH7-8, stirring evenly; dripping initiator, dropping is complete, the mixed solution becomes viscous, warming up to 65-70°C, continuing to react 4-8h, cooling to less than 30°C, adding ethanol, precipitating, filtering, drying overnight, and obtaining the product, i.e., clay stabilizer. The clay stabilizer of the present invention has the advantages of high anti-swelling rate and water-resistant.

Description

Technical Field

[0001] The invention belongs to the technical field of oil extraction, and in particular relates to a clay stabilizer for oil fields and a preparation method and application thereof. Background Art

[0002] Unconventional reservoirs have poor physical properties, small porosity and low permeability. The injected water can easily break through and flush the high permeability layer, further increasing the permeability of the high permeability layer and further expanding the heterogeneity of the reservoir, causing large amounts of water to flow out of the oil wells, reducing production capacity and worsening economic benefits.

[0003] These oil and gas reservoirs are usually deep, low in permeability, and high in temperature, and require fracturing. During the fracturing process, a large amount of aqueous solution comes into contact with clay, which expands due to its high water sensitivity. During the expansion process, the clay absorbs water into the crystal structure, resulting in an increase in the volume of the clay, which blocks the pores of the formation. At the same time, during the migration process, the clay material is dispersed by foreign liquids or carried by the produced fluid, forming a bridge or throttling point at the pore throat of the capillary, which then leads to a decrease in the permeability of the reservoir.

[0004] In order to inhibit the reduction of oil and gas layer permeability, prevent clay expansion and migration from damaging reservoirs, and achieve high and stable production of oil and gas fields, an effective oilfield chemical treatment agent - clay stabilizer is widely used.

[0005] Generally speaking, clay stabilizers used for water injection are not only required to have high anti-swelling effect and low effective use concentration, but also need to have good compatibility with formation water, stable and lasting expansion inhibition effect on clay in the formation, and resistance to erosion by various fluids.

[0006] CN106147739A discloses a fracturing clay stabilizer and a preparation method thereof, which is prepared from the following raw materials in parts by weight: 35-50 parts of choline chloride, 3-8 parts of calcium chloride, 40-50 parts of water, 5-10 parts of methanol and 1-5 parts of alcohol ether solvent; the preparation method of the fracturing clay stabilizer comprises the following specific steps: (1) weighing choline chloride and methanol according to the above formula and mixing them evenly to obtain component a; (2) adding the formula amount of water, calcium chloride and alcohol ether solvent to component a obtained in step (1) in sequence, stirring until the solid is completely dissolved, and discharging the material. The fracturing clay stabilizer prepared by the method has excellent anti-swelling performance and good compatibility. However, the clay stabilizer of the invention contains a large amount of methanol and alcohol ether, which are easily washed away by water, indicating that the clay stabilizer has limited water washing resistance and an anti-swelling rate of only 50%, which cannot meet actual needs.

[0007] CN114106795A discloses a clay stabilizer and its preparation method and application, belonging to the technical field of clay stabilizers. The clay stabilizer, by weight, comprises: 2-8 parts of bisindolylmethane compounds, 2-8 parts of quinazolinone compounds, 5-15 parts of methanol and 80-85 parts of water. The clay stabilizer has a small molecular weight, which is conducive to dispersion on the clay surface, has high anti-swelling efficiency, and is easy to discharge. After fracturing or mining operations, it can reduce residues and reduce damage to the formation. However, from the perspective of molecular structure, the invention belongs to non-ionic organic matter, and has limited adsorption effect on negatively charged clay, thus affecting the anti-swelling effect to some extent. Summary of the invention

[0008] The present invention aims at the above-mentioned deficiencies of the prior art and provides a clay stabilizer for oil fields and its preparation method and application. The clay stabilizer of the present invention has the advantages of high anti-swelling rate and water-resistant.

[0009] One of the purposes of the present invention is to disclose a method for preparing a clay stabilizer for oil fields, and the specific steps of the preparation method are as follows:

[0010] (1) Add dodecylamine, ethanol and allyl chloride into the reactor, introduce nitrogen, heat, and control the temperature at 50-60°C. During this period, add potassium hydroxide solution dropwise to maintain the pH at 7-8;

[0011] (2) The mixed solution in the above reactor was distilled under reduced pressure to 70°C until no distillate was produced. 2-(allyldimethylsilyl)pyridine, 3-(methacrylamido)propyldimethyl(3-sulfopropyl)ammonium inner salt, 1-vinyl-3-ethylimidazolium bromide, potassium dihydrogen phosphate, and deionized water were added in sequence. The pH was adjusted to 7-8 with potassium hydroxide solution, and the mixture was stirred evenly.

[0012] (3) Add the initiator dropwise to the above reactor. After the addition is completed, the mixed solution becomes viscous and the temperature is raised to 65-70°C. The reaction is continued for 4-8 hours. The temperature is lowered to below 30°C, ethanol is added, and a precipitate is precipitated. The solid is filtered and dried at 105°C overnight to obtain the product, i.e., the clay stabilizer.

[0013] In the present invention, preferably, based on 1 mol part of dodecylamine, the amounts of allyl chloride, 2-(allyldimethylsilyl)pyridine, 3-(methacrylamido)propyldimethyl(3-sulfopropyl)ammonium inner salt, and 1-vinyl-3-ethylimidazolium bromide are 0.8-1.2 mol parts, 0.05-0.1 mol parts, 1-2 mol parts, and 0.2-0.4 mol parts, respectively.

[0014] In the present invention, preferably, the weight ratio of ethanol to dodecylamine in step (1) is 10-15:1.

[0015] In the present invention, preferably, the weight ratio of potassium dihydrogen phosphate, deionized water and dodecylamine in step (2) is 0.1-0.2:30-60:1.

[0016] In the present invention, preferably, the initiator in step (3) is an aqueous solution of persulfate and sodium bisulfite, and the weight ratio of the initiator to dodecylamine is 0.5-1:1.

[0017] Preferably, the persulfate is one of potassium persulfate, ammonium persulfate and sodium persulfate.

[0018] Preferably, the concentration of the persulfate is 8-10wt%, and the concentration of the sodium bisulfite is 3-5wt%.

[0019] In the present invention, preferably, the weight ratio of ethanol to dodecylamine in step (3) is 30-60:1.

[0020] The reaction equation of the oil field clay stabilizer of the present invention is as follows:

[0021]

[0022]

[0023]

[0024]

[0025] Another object of the present invention is to disclose a clay stabilizer for oil fields, wherein the molecular structure of the clay stabilizer is as follows:

[0026]

[0027] Where, a=200-2000;

[0028] b = 10-200;

[0029] c = 200-4000;

[0030] d=40-800.

[0031] Preferably, the viscosity average molecular weight of the clay stabilizer is 200,000-500,000.

[0032] The third object of the present invention is to disclose the application of the above-mentioned clay stabilizer in oil fields.

[0033] The oil field clay stabilizer of the present invention belongs to a high molecular surfactant. The quaternary ammonium and imidazoline in the molecule are both cations, and the pyridine is also positive, which can adsorb and neutralize the negative charge on the surface of the clay, increase the electrostatic attraction, reduce the repulsion between crystal layers, and play an anti-swelling effect; the silicon in the molecule is easily adsorbed and firmly combined with the silicon in the clay; the molecule has quaternary ammonium salt cations and sulfonic acid anions, so it is less affected by pH; the dodecyl group is a hydrophobic group, which can effectively prevent water molecules from infiltrating the clay particles, thereby controlling the hydration expansion of the clay.

[0034] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0035] (1) The oilfield clay stabilizer of the present invention has the advantage of a high anti-swelling rate, which can reach up to 99%;

[0036] (2) The oil field clay stabilizer of the present invention has the advantage of being resistant to water washing, and the anti-swelling rate after water washing can reach up to 95.3%. DETAILED DESCRIPTION

[0037] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0038] The present invention will be further described below in conjunction with specific embodiments:

[0039] Example 1

[0040] (1) Add 40 mmol of dodecylamine, 74 g of ethanol, and 32 mmol of allyl chloride into a reactor, introduce nitrogen, heat, and control the temperature at 50°C. During this period, potassium hydroxide solution is added dropwise to maintain the pH at 7-8;

[0041] (2) The mixed solution in the above reactor was distilled under reduced pressure to 70°C until no distillate was produced. Then, 2 mmol 2-(allyldimethylsilyl)pyridine, 40 mmol 3-(methacrylamido)propyldimethyl(3-sulfopropyl)ammonium inner salt, 16 mmol 1-vinyl-3-ethylimidazolium bromide, 0.74 g potassium dihydrogen phosphate, and 222 g deionized water were added in sequence. The pH was adjusted to 7-8 with potassium hydroxide solution, and the mixture was stirred evenly.

[0042] (3) 3.7 g of initiator was added dropwise to the above reactor. The initiator was a mixture of 10 wt % potassium persulfate and 5 wt % sodium bisulfite. After the addition was completed, the mixture became viscous and the temperature was raised to 65° C. The reaction was continued for 8 h. The temperature was lowered to below 30° C. 222 g of ethanol was added to precipitate. The solid was filtered and dried at 105° C. overnight to obtain a clay stabilizer product.

[0043] Example 2

[0044] (1) Add 40 mmol of dodecylamine, 88 g of ethanol, and 34 mmol of allyl chloride into a reactor, introduce nitrogen, heat, and control the temperature at 60°C. During this period, potassium hydroxide solution is added dropwise to maintain the pH at 7-8;

[0045] (2) The mixed solution in the above reactor was distilled under reduced pressure to 70°C until no distillate was produced. Then, 2.5 mmol 2-(allyldimethylsilyl)pyridine, 45 mmol 3-(methacrylamido)propyldimethyl(3-sulfopropyl)ammonium inner salt, 15 mmol 1-vinyl-3-ethylimidazolium bromide, 0.88 g potassium dihydrogen phosphate, and 248 g deionized water were added in sequence. The pH was adjusted to 7-8 with potassium hydroxide solution, and the mixture was stirred evenly.

[0046] (3) 4.2 g of initiator was added dropwise to the above reactor. The initiator was a mixture of 9 wt % potassium persulfate and 4 wt % sodium bisulfite. After the addition was completed, the mixture became viscous and the temperature was raised to 70°C. The reaction was continued for 4 h, and the temperature was lowered to below 30°C. 252 g of ethanol was added to precipitate. The solid was filtered and dried at 105°C overnight to obtain the product clay stabilizer.

[0047] Example 3

[0048] (1) Add 40 mmol of dodecylamine, 92 g of ethanol, and 36 mmol of allyl chloride into a reactor, introduce nitrogen, heat, and control the temperature at 55°C. During this period, potassium hydroxide solution is added dropwise to maintain the pH at 7-8;

[0049] (2) The mixed solution in the above reactor was distilled under reduced pressure to 70°C until no distillate was produced. Then, 3 mmol 2-(allyldimethylsilyl)pyridine, 50 mmol 3-(methacrylamido)propyldimethyl(3-sulfopropyl)ammonium inner salt, 14 mmol 1-vinyl-3-ethylimidazolium bromide, 0.94 g potassium dihydrogen phosphate, and 278 g deionized water were added in sequence. The pH was adjusted to 7-8 with potassium hydroxide solution, and the mixture was stirred evenly.

[0050] (3) 4.7 g of initiator was added dropwise to the above reactor. The initiator was a mixture of 10 wt% ammonium persulfate and 4 wt% sodium bisulfite. After the addition was completed, the mixture became viscous and the temperature was raised to 70°C. The reaction was continued for 4 h, and the temperature was lowered to below 30°C. 282 g of ethanol was added to precipitate. The solid was filtered and dried at 105°C overnight to obtain the product clay stabilizer.

[0051] Example 4

[0052] (1) Add 40 mmol of dodecylamine, 98 g of ethanol, and 38 mmol of allyl chloride into a reactor, introduce nitrogen, heat, and control the temperature at 55°C. During this period, potassium hydroxide solution is added dropwise to maintain the pH at 7-8;

[0053] (2) The mixed solution in the above reactor was distilled under reduced pressure to 70°C until no distillate was produced. Then, 3 mmol 2-(allyldimethylsilyl)pyridine, 60 mmol 3-(methacrylamido)propyldimethyl(3-sulfopropyl)ammonium inner salt, 12 mmol 1-vinyl-3-ethylimidazolium bromide, 1.04 g potassium dihydrogen phosphate, and 302 g deionized water were added in sequence. The pH was adjusted to 7-8 with potassium hydroxide solution, and the mixture was stirred evenly.

[0054] (3) 5.4 g of initiator was added dropwise to the above reactor. The initiator was a mixture of 9 wt% ammonium persulfate and 3 wt% sodium bisulfite. After the addition was completed, the mixture became viscous and the temperature was raised to 68°C. The reaction was continued for 6 h, and the temperature was lowered to below 30°C. 316 g of ethanol was added to precipitate. The solid was filtered and dried at 105°C overnight to obtain the product clay stabilizer.

[0055] Example 5

[0056] (1) Add 40 mmol of dodecylamine, 102 g of ethanol, and 40 mmol of allyl chloride into a reactor, introduce nitrogen, heat, and control the temperature at 58°C. During this period, potassium hydroxide solution is added dropwise to maintain the pH at 7-8;

[0057] (2) The mixed solution in the above reactor was distilled under reduced pressure to 70°C until no distillate was produced. Then, 3.5 mmol 2-(allyldimethylsilyl)pyridine, 70 mmol 3-(methacrylamido)propyldimethyl(3-sulfopropyl)ammonium inner salt, 10 mmol 1-vinyl-3-ethylimidazolium bromide, 1.24 g potassium dihydrogen phosphate, and 362 g deionized water were added in sequence. The pH was adjusted to 7-8 with potassium hydroxide solution, and the mixture was stirred evenly.

[0058] (3) 5.7 g of initiator was added dropwise to the above reactor. The initiator was a mixture of 10 wt % sodium persulfate and 4 wt % sodium bisulfite. After the addition was completed, the mixture became viscous and the temperature was raised to 67° C. The reaction was continued for 4 h. The temperature was lowered to below 30° C. 384 g of ethanol was added to precipitate. The solid was filtered and dried at 105° C. overnight to obtain a clay stabilizer product.

[0059] Example 6

[0060] (1) Add 40 mmol of dodecylamine, 110 g of ethanol, and 44 mmol of allyl chloride into a reactor, introduce nitrogen, heat, and control the temperature at 60°C. During this period, potassium hydroxide solution is added dropwise to maintain the pH at 7-8;

[0061] (2) The mixed solution in the above reactor was distilled under reduced pressure to 70°C until no distillate was produced. Then, 4 mmol of 2-(allyldimethylsilyl)pyridine, 75 mmol of 3-(methacrylamido)propyldimethyl(3-sulfopropyl)ammonium inner salt, 9 mmol of 1-vinyl-3-ethylimidazolium bromide, 1.4 g of potassium dihydrogen phosphate, and 400 g of deionized water were added in sequence. The pH was adjusted to 7-8 with potassium hydroxide solution, and the mixture was stirred evenly.

[0062] (3) 6.7 g of initiator was added dropwise to the above reactor. The initiator was a mixture of 9 wt % sodium persulfate and 4 wt % sodium bisulfite. After the addition was completed, the mixture became viscous and the temperature was raised to 70° C. The reaction was continued for 8 h. The temperature was lowered to below 30° C. 428 g of ethanol was added to precipitate. The solid was filtered and dried at 105° C. overnight to obtain a clay stabilizer product.

[0063] Example 7

[0064] (1) Add 40 mmol of dodecylamine, 111 g of ethanol, and 48 mmol of allyl chloride into a reactor, introduce nitrogen, heat, and control the temperature at 58°C. During this time, add potassium hydroxide solution dropwise to maintain the pH at 7-8;

[0065] (2) The mixed solution in the above reactor was distilled under reduced pressure to 70°C until no distillate was produced. Then, 4 mmol of 2-(allyldimethylsilyl)pyridine, 80 mmol of 3-(methacrylamido)propyldimethyl(3-sulfopropyl)ammonium inner salt, 16 mmol of 1-vinyl-3-ethylimidazolium bromide, 1.48 g of potassium dihydrogen phosphate, and 444 g of deionized water were added in sequence. The pH was adjusted to 7-8 with potassium hydroxide solution, and the mixture was stirred evenly.

[0066] (3) 7.4 g of initiator was added dropwise to the above reactor. The initiator was a mixture of 8 wt % potassium persulfate and 3 wt % sodium bisulfite. After the addition was completed, the mixture became viscous and the temperature was raised to 68° C. The reaction was continued for 7 h. The temperature was lowered to below 30° C. 444 g of ethanol was added to precipitate. The solid was filtered and dried at 105° C. overnight to obtain a clay stabilizer product.

[0067] Example 8 Evaluation of the Anti-swelling Capacity of Clay Stabilizer

[0068] The evaluation method refers to SY / T5971-2016 "Performance Evaluation Method of Clay Stabilizer for Oil and Gas Field Fracturing Acidizing and Water Injection" and the anti-swelling rate is tested by centrifugal method. The anti-swelling rate test results of clay stabilizer are shown in Table 1. At the same time, the fracturing acidizing clay stabilizer of Tianjin Xiongguan Technology Development Co., Ltd. was used for comparative experiments.

[0069] It can be seen from Table 1 that the anti-swelling rate of the clay stabilizer of the present invention is greater than 98%, and the highest is 99%; while the anti-swelling rate of the comparative example is 89.8%. Therefore, the clay stabilizer for oil fields of the present invention has the advantage of a high anti-swelling rate.

[0070] Example 9 Evaluation of the water washability of clay stabilizers

[0071] The evaluation method refers to SY / T5971-2016 "Performance Evaluation Method of Clay Stabilizer for Oil and Gas Field Fracturing Acidizing and Water Injection" and the centrifugal method is used to test the water wash resistance. The water wash resistance test results are shown in Table 1. At the same time, the fracturing acidizing clay stabilizer of Tianjin Xiongguan Technology Development Co., Ltd. was used for comparative experiments.

[0072] Table 1 Test results of anti-swelling rate and water washability

[0073]

[0074] It can be seen from Table 1 that the water-washing anti-swelling rate of the clay stabilizer of the present invention is above 94%, with the highest reaching 95.3%; while the water-washing anti-swelling rate of the comparative example is 82.1%. The clay stabilizer for oil fields of the present invention has the advantage of being resistant to water washing.

[0075] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0076] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0077] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A method for preparing a clay stabilizer for oil fields, characterized in that: The specific steps of the preparation method are as follows: (1) Add dodecylamine, ethanol and allyl chloride into the reactor, introduce nitrogen, heat, and control the temperature at 50-60°C. During this period, add potassium hydroxide solution dropwise to maintain the pH at 7-8; (2) The mixed solution in the above reactor was distilled under reduced pressure to 70°C until no distillate was produced. 2-(allyldimethylsilyl)pyridine, 3-(methacrylamido)propyldimethyl(3-sulfopropyl)ammonium inner salt, 1-vinyl-3-ethylimidazolium bromide, potassium dihydrogen phosphate, and deionized water were added in sequence. The pH was adjusted to 7-8 with potassium hydroxide solution, and the mixture was stirred evenly. (3) Add initiator dropwise to the reactor. After the addition is complete, the mixed solution becomes viscous and the temperature is raised to 65-70°C. The reaction is continued for 4-8 hours. The temperature is lowered to below 30°C, ethanol is added to precipitate, and the solid is filtered to obtain a solid. The solid is dried at 105°C overnight to obtain a product, i.e., a clay stabilizer. Based on 1 mole of dodecylamine, the amounts of allyl chloride, 2-(allyldimethylsilyl)pyridine, 3-(methacrylamido)propyldimethyl(3-sulfopropyl)ammonium inner salt, and 1-vinyl-3-ethylimidazolium bromide are 0.8-1.2 mole parts, 0.05-0.1 mole parts, 1-2 mole parts, and 0.2-0.4 mole parts, respectively; The molecular structure of the clay stabilizer is as follows: ， Where, a=200-2000; b=10-200； c=200-4000； d=40-800。 2. The preparation method according to claim 1, characterized in that: The weight ratio of ethanol to dodecylamine in step (1) is 10-15:

1.

3. The preparation method according to claim 1, characterized in that: The weight ratio of potassium dihydrogen phosphate, deionized water and dodecylamine in step (2) is 0.1-0.2:30-60:

1.

4. The preparation method according to claim 1, characterized in that: The initiator in step (3) is an aqueous solution of persulfate and sodium bisulfite, and the weight ratio of the initiator to dodecylamine is 0.5-1:

1.

5. The preparation method according to claim 4, characterized in that: The persulfate is one of potassium persulfate, ammonium persulfate and sodium persulfate.

6. The preparation method according to claim 4, characterized in that: The concentration of the persulfate is 8-10wt%, and the concentration of the sodium bisulfite is 3-5wt%.

7. The preparation method according to claim 1, characterized in that: The weight ratio of ethanol to dodecylamine in step (3) is 30-60:

1.

8. The clay stabilizer prepared according to the preparation method according to any one of claims 1 to 7, wherein the molecular structure of the clay stabilizer is as follows: ， in, a=200-2000； b=10-200； c=200-4000； d=40-800。 9. The clay stabilizer according to claim 8, characterized in that: The viscosity average molecular weight of the clay stabilizer is 200,000-500,000.

10. Use of the clay stabilizer according to claim 8 or 9 in oil fields.

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