An acidic gelling agent for oil extraction and its preparation method

Abstract

The present invention relates to the technical field of gelling agents for acid fracturing operations, and specifically relates to an acidic gelling agent for oil extraction and a preparation method thereof. The present invention prepares modified hydroxypropyl guar gum by modifying hydroxypropyl guar gum powder with oleic acid amide propyl dimethyl tertiary amine, which can improve its high-temperature resistance while maintaining good crosslinkability of the hydroxypropyl guar gum powder, so that the modified hydroxypropyl guar gum after high-temperature modification can be applied to the compounding of gelling agents; secondly, during the crosslinking of nano-titanium dioxide and modified hydroxypropyl guar gum, self-made carboxymethyl hydroxypropyl guar gum and self-made gelling polymer are added, which can improve the viscosity-increasing effect of the gelling agent through organic-inorganic hybrid crosslinking. The self-made carboxymethyl hydroxypropyl guar gum introduces methyl hydroxy and propyl guanidine structures on the surface of the guar gum, which can make it have better high-temperature resistance while increasing the viscosity.

Description

Technical Field

[0001] The present invention relates to the technical field of gelling agents for acid fracturing operations, and particularly relates to an acidic gelling agent for oil extraction and a preparation method thereof. Background Art

[0002] Acidification is the main measure for increasing production in oil and gas wells and injection in water wells. Through the dissolution of the formation by acid fluid, acid-etched pores can be formed in the formation, thereby improving the conductivity of the reservoir and increasing the production of oil and gas wells. With the progress of oil and gas exploration and development, the number of deep wells and ultra-deep wells is increasing day by day. Ordinary acid fluid systems have a fast reaction rate at high temperatures and it is difficult to form long dissolution pores. In order to slow down the acid-rock reaction rate, it is often necessary to add a gelling agent to the acid fluid. The acidification gelling agent is the key to acid fracturing operations and plays a decisive role in the acidification effect. During acid fracturing operations, by adding an acidification gelling agent to the acid, the viscosity of the acid fluid is increased, and the network structure of the polymer restricts the activity of hydrogen ions in the acid to reduce the propagation speed of the acid in the fracture and the filtration loss in the fracture, thereby increasing the acidification time towards the rock wall.

[0003] For example, a gelling agent for acid fracturing operations and a preparation method thereof disclosed in Chinese Patent No. CN201711472441.1. The gelling agent prepared by this invention has strong stability, has the characteristics of high temperature resistance, high viscosity, no residue, and simple usage method. However, the composition of the gelling agent prepared by this invention is relatively single, and the raw material is only an organic polymer. If it is improved by the method of organic-inorganic hybrid crosslinking, the viscosity under acidic conditions can be greatly improved, thereby enhancing its market application value. Summary of the Invention

[0004] Technical Problem to be Solved

[0005] In view of the above-mentioned drawbacks of the prior art, the present invention provides an acidic gelling agent for oil extraction and a preparation method thereof, aiming to prepare a gelling agent with high temperature resistance and good viscosity by the method of organic-inorganic hybrid crosslinking.

[0006] Technical Solution

[0007] To achieve the above object, the present invention is realized through the following technical solutions:

[0008] A preparation method of an acidic gelling agent for oil extraction, the preparation method is as follows:

[0009] S1. Weigh 30 - 32 parts by weight of oleic acid amide propyl dimethyl tertiary amine and 50 - 55 parts by weight of ethanol aqueous solution and pour them into a three-necked flask. Under stirring conditions, add glacial acetic acid to adjust the pH value to 5 - 6, and then add 10 - 12 parts by weight of epichlorohydrin under the water bath condition of 60 °C. After reacting for 3 - 4 h, the obtained product is denoted as the intermediate component;

[0010] S2. Mix 3 - 4 parts by weight of hydroxypropyl guar gum powder and 30 - 35 parts by weight of an aqueous ethanol solution, then add a sodium hydroxide solution to adjust the pH value to 8, alkalize at a temperature of 25°C for 40 - 45 min, add dropwise the intermediate component in S1 under a water bath condition of 80°C, react for 3 - 4 h to obtain a product, wash it 3 times with absolute ethanol, and record it as modified hydroxypropyl guar gum after suction filtration and drying;

[0011] S3. Weigh 6 - 7 parts by weight of nano - silica and pour it into 50 - 55 parts by weight of absolute ethanol, ultrasonically disperse it at a frequency of 23 - 25 kHz for 30 min, then add 5 - 6 parts by weight of 3 - aminopropyltriethoxysilane, reflux for 12 h, and remove absolute ethanol by rotary evaporation. Record the obtained product as modified silica;

[0012] S4. Weigh 8 - 10 parts by weight of n - butanol, 15 - 18 parts by weight of ethylene glycol and 6 - 8 parts by weight of boric acid and mix them, stir at a stirring speed of 400 - 500 r / min at a temperature of 35°C for 30 min, then add the modified silica in S3, and stir at the original stirring speed at a temperature of 100°C for 4 - 5 h. Record the obtained product as nano - organic boron cross - linked component;

[0013] S5. Add 2 - 3 parts by weight of potassium chloride to 100 parts by weight of deionized water, stir at a stirring speed of 600 - 800 r / min for 10 min, then add 5 - 8 parts by weight of the modified hydroxypropyl guar gum in S2 and 2 - 3 parts by weight of self - made carboxymethyl hydroxypropyl guar gum, stir at the original stirring speed for 10 min, and then place it at a temperature of 30°C for 4 h. Record the obtained product as pre - cross - linked component;

[0014] S6. Add a nano - organic boron cross - linked component with a weight of 5% of that in S5 and a self - made gum polymer with a weight of 3% of that in S5 to the pre - cross - linked component in S5, and stir at high speed for 3 min. The obtained product is the acidic gelling agent for oil exploitation.

[0015] Furthermore, the mass fraction of the aqueous ethanol solution in S1 is 60%, and the stirring speed in S1 is 300 - 400 r / min.

[0016] Furthermore, the mass fraction of the aqueous ethanol solution in S2 is 80%, the mass fraction of the sodium hydroxide solution in S2 is 2%, the drying temperature in S2 is 50°C, and the drying time is 24 h.

[0017] Further, the preparation method of the nano-silica in S3 is as follows: Mix 5 parts by weight of ammonia water and 50 parts by weight of absolute ethanol, stir at a stirring speed of 800 - 1000 r / min for 30 min, then add 3 parts by weight of tetraethyl orthosilicate. Subsequently, stir at a stirring speed of 500 - 600 r / min for 24 h, wash 3 times with absolute ethanol, dry in an oven at 55 °C, and then grind through a 200-mesh sieve. What is obtained is the nano-silica.

[0018] Further, the preparation method of the self-made carboxymethyl hydroxypropyl guar gum in S5 is as follows: Weigh 10 parts by weight of guanidine gum sheets and 100 parts by weight of tetrahydrofuran and pour them into a flask. Adjust the pH value to 9 with sodium hydroxide solution and react at a temperature of 25 °C for 50 min. Then, dropwise add 4 parts by weight of sodium chloroacetate solution and react for 30 min. Subsequently, dropwise add 5 parts by weight of propylene oxide and carry out a condensation reflux reaction at a temperature of 45 °C. After reacting for 4 h, neutralize to neutral with glacial acetic acid. Finally, wash with absolute ethanol and dry at a temperature of 50 °C. What is obtained is the self-made carboxymethyl hydroxypropyl guar gum.

[0019] Further, in the preparation method of the self-made carboxymethyl hydroxypropyl guar gum, the mass fraction of the sodium hydroxide solution is 40%, and the mass fraction of the sodium chloroacetate solution is 20%.

[0020] Further, the preparation method of the self-made gel polymer in S6 includes the following steps:

[0021] Step 1: Weigh 8 parts by weight of 2-acrylamido-2-methylpropanesulfonic acid and 50 parts by weight of deionized water and mix them. Adjust the pH value to 7, then add 5 parts by weight of acrylamide and 2 parts by weight of dimethyldiallylammonium chloride, and react for 30 min under a nitrogen atmosphere. What is obtained is denoted as the mixed component;

[0022] Step 2: Add an initiator component with a weight of 0.3% of that in Step 1 to the mixed component in Step 1, continue to react for 10 min under a nitrogen atmosphere, then seal, and react at a temperature of 40 °C for 4 - 5 h. After the reaction is completed, pour it into isopropanol to obtain a white product. Wash 3 times with absolute ethanol, dry, grind through a 100-mesh sieve. What is obtained is the self-made gel polymer.

[0023] Further, the initiator component is prepared by mixing potassium persulfate and sodium bisulfite in a weight ratio of 2:1.

[0024] Further, the stirring speed of the high-speed stirring in S6 is 800 - 1000 r / min.

[0025] An acidic gelling agent for oil exploitation, the raw materials of the acidic gelling agent for oil exploitation comprising the following components: oleic acid amide propyl dimethyl tertiary amine, an ethanol aqueous solution with a mass fraction of 60%, glacial acetic acid, hydroxypropyl guar gum powder, an ethanol aqueous solution with a mass fraction of 80%, a sodium hydroxide solution with a mass fraction of 2%, absolute ethanol, ammonia water, tetraethyl orthosilicate, 3-aminopropyltriethoxysilane, n-butanol, ethylene glycol, boric acid, potassium chloride, guanidine film, tetrahydrofuran, a sodium hydroxide solution with a mass fraction of 40%, a sodium chloroacetate solution with a mass fraction of 20%, propylene oxide, 2-acrylamide-2-methylpropanesulfonic acid, acrylamide, dimethyldiallylammonium chloride, potassium persulfate, sodium bisulfite and isopropanol.

[0026] Advantageous effects

[0027] The present invention provides an acidic gelling agent for oil exploitation and a preparation method thereof. Compared with the existing well-known technologies, the present invention has the following advantageous effects:

[0028] In the present invention, modified hydroxypropyl guar gum is prepared by modifying hydroxypropyl guar gum powder with oleic acid amide propyl dimethyl tertiary amine. On the basis of maintaining good crosslinkability of the hydroxypropyl guar gum powder, its high-temperature resistance performance can be improved, so that the modified hydroxypropyl guar gum after high-temperature modification can be applied to the compounding of the gelling agent. Secondly, during the crosslinking process of nano-titanium dioxide and modified hydroxypropyl guar gum, self-made carboxymethyl hydroxypropyl guar gum and self-made gel polymer are added, and the thickening effect of the gelling agent can be improved by means of organic-inorganic hybrid crosslinking. Among them, self-made carboxymethyl hydroxypropyl guar gum introduces methyl hydroxy and propyl guanidine structures on the surface of the guar gum, enabling it to have better high-temperature resistance while increasing the viscosity. The self-made gel polymer is polymerized with 2-acrylamide-2-methylpropanesulfonic acid, acrylamide and dimethyldiallylammonium chloride as raw material monomers, enabling the prepared polymer to have better acidification performance. Applying the self-made gel polymer to the compounding of the gelling agent can improve the thickening performance of the gelling agent. Specific embodiments

[0029] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts shall fall within the protection scope of the present invention.

[0030] The present invention will be further described below in conjunction with the embodiments.

[0031] Example 1

[0032] A preparation method of an acidic gelling agent for oil extraction in this embodiment, the preparation method is as follows:

[0033] S1. Weigh 30 parts by weight of oleic acid amide propyl dimethyl tertiary amine and 50 parts by weight of ethanol aqueous solution and pour them into a three-necked flask. Add glacial acetic acid to adjust the pH value to 5 under stirring conditions, and then add 10 parts by weight of epichlorohydrin under the water bath condition of 60 °C. After reacting for 3 h, the obtained product is recorded as the intermediate component;

[0034] S2. Mix 3 parts by weight of hydroxypropyl guar gum powder and 30 parts by weight of ethanol aqueous solution, then add sodium hydroxide solution to adjust the pH value to 8, alkalize at 25 °C for 40 min, and dropwise add the intermediate component in S1 under the water bath condition of 80 °C. After reacting for 3 h, the product is obtained, washed 3 times with absolute ethanol, and the obtained product after suction filtration and drying is recorded as modified hydroxypropyl guar gum;

[0035] S3. Weigh 6 parts by weight of nano-silica and pour it into 50 parts by weight of absolute ethanol, ultrasonically disperse it at a frequency of 23 kHz for 30 min, then add 5 parts by weight of 3-aminopropyltriethoxysilane, reflux for 12 h, and then remove absolute ethanol by rotary evaporation. The obtained product is recorded as modified silica;

[0036] S4. Weigh 8 parts by weight of n-butanol, 15 parts by weight of ethylene glycol and 6 parts by weight of boric acid and mix them. Stir at a stirring speed of 400 r / min at 35 °C for 30 min, then add the modified silica in S3, and stir at the original stirring speed at 100 °C for 4 h. The obtained product is recorded as nano-organic boron crosslinking component;

[0037] S5. Add 2 parts by weight of potassium chloride to 100 parts by weight of deionized water, stir at a stirring speed of 600 r / min for 10 min, then add 5 parts by weight of the modified hydroxypropyl guar gum in S2 and 2 parts by weight of self-made carboxymethyl hydroxypropyl guar gum, stir at the original stirring speed for 10 min, and then place it at 30 °C for 4 h. The obtained product is recorded as the pre-crosslinked component;

[0038] S6. Add 5% by weight of the nano-organic boron crosslinking component and 3% by weight of the self-made gel polymer to the pre-crosslinked component in S5, and stir at high speed for 3 min. The obtained product is the acidic gelling agent for oil extraction.

[0039] The mass fraction of the ethanol aqueous solution in S1 is 60%, and the stirring speed of stirring in S1 is 300 r / min.

[0040] The mass fraction of the ethanol aqueous solution in S2 is 80%, the mass fraction of the sodium hydroxide solution in S2 is 2%, the drying temperature of drying in S2 is 50 °C, and the drying time is 24 h.

[0041] The preparation method of nano-silica in S3 is as follows: Mix 5 parts by weight of ammonia water and 50 parts by weight of absolute ethanol, stir at a stirring speed of 800 r / min for 30 min, then add 3 parts by weight of tetraethyl orthosilicate, and then stir at a stirring speed of 500 r / min for 24 h. Wash with absolute ethanol 3 times, dry in an oven at 55 °C, and then grind through a 200-mesh sieve. The obtained product is nano-silica.

[0042] The preparation method of self-made carboxymethyl hydroxypropyl guar gum in S5 is as follows: Weigh 10 parts by weight of guar gum sheets and 100 parts by weight of tetrahydrofuran and pour them into a flask. Adjust the pH value to 9 with sodium hydroxide solution and react at a temperature of 25 °C for 50 min. Then, dropwise add 4 parts by weight of sodium chloroacetate solution and react for 30 min. Then, dropwise add 5 parts by weight of propylene oxide and carry out a condensation reflux reaction at a temperature of 45 °C. After reacting for 4 h, neutralize to neutral with glacial acetic acid. Finally, wash with absolute ethanol and dry at a temperature of 50 °C. The obtained product is self-made carboxymethyl hydroxypropyl guar gum.

[0043] In the preparation method of self-made carboxymethyl hydroxypropyl guar gum, the mass fraction of the sodium hydroxide solution is 40%, and the mass fraction of the sodium chloroacetate solution is 20%.

[0044] The preparation method of self-made gel polymer in S6 includes the following steps:

[0045] Step 1: Weigh 8 parts by weight of 2-acrylamide-2-methylpropanesulfonic acid and 50 parts by weight of deionized water and mix them. Adjust the pH value to 7, then add 5 parts by weight of acrylamide and 2 parts by weight of dimethyldiallylammonium chloride, and react for 30 min under a nitrogen atmosphere. The obtained product is denoted as the mixed component.

[0046] Step 2: Add an initiator component with a weight of 0.3% of the mixed component in Step 1, continue to react for 10 min under a nitrogen atmosphere, then seal, and react at a temperature of 40 °C for 4 h. After the reaction is completed, pour it into isopropanol to obtain a white product. Wash with absolute ethanol 3 times and then dry, and grind through a 100-mesh sieve. The obtained product is self-made gel polymer.

[0047] The initiator component is prepared by mixing potassium persulfate and sodium bisulfite in a weight ratio of 2:1.

[0048] The stirring speed of high-speed stirring in S6 is 800 r / min.

[0049] An acidic gelling agent for oil extraction, the raw materials of the acidic gelling agent for oil extraction include the following components: oleic acid amide propyl dimethyl tertiary amine, ethanol aqueous solution with a mass fraction of 60%, glacial acetic acid, hydroxypropyl guar gum powder, ethanol aqueous solution with a mass fraction of 80%, sodium hydroxide solution with a mass fraction of 2%, absolute ethanol, ammonia water, tetraethyl orthosilicate, 3-aminopropyltriethoxysilane, n-butanol, ethylene glycol, boric acid, potassium chloride, guanidine film, tetrahydrofuran, sodium hydroxide solution with a mass fraction of 40%, sodium chloroacetate solution with a mass fraction of 20%, propylene oxide, 2-acrylamide-2-methylpropanesulfonic acid, acrylamide, dimethyldiallylammonium chloride, potassium persulfate, sodium bisulfite and isopropanol.

[0050] Example 2

[0051] The preparation method of an acidic gelling agent for oil extraction in this example is as follows:

[0052] S1. Weigh 32 parts by weight of oleic acid amide propyl dimethyl tertiary amine and 55 parts by weight of ethanol aqueous solution and pour them into a three-necked flask. Under stirring conditions, add glacial acetic acid to adjust the pH value to 6, and then add 12 parts by weight of epichlorohydrin under the water bath condition of 60°C. After reacting for 4 h, the obtained product is recorded as the intermediate component;

[0053] S2. Mix 4 parts by weight of hydroxypropyl guar gum powder and 35 parts by weight of ethanol aqueous solution, then add sodium hydroxide solution to adjust the pH value to 8, alkalize at a temperature of 25°C for 45 min, and dropwise add the intermediate component in S1 under the water bath condition of 80°C. After reacting for 4 h, the product is obtained, washed 3 times with absolute ethanol, and dried by suction filtration. The obtained product is recorded as modified hydroxypropyl guar gum;

[0054] S3. Weigh 7 parts by weight of nano-silica and pour it into 55 parts by weight of absolute ethanol, ultrasonically disperse it at a frequency of 25 kHz for 30 min, then add 6 parts by weight of 3-aminopropyltriethoxysilane, reflux for 12 h, and then remove absolute ethanol by rotary evaporation. The obtained product is recorded as modified silica;

[0055] S4. Weigh 10 parts by weight of n-butanol, 18 parts by weight of ethylene glycol and 8 parts by weight of boric acid and mix them. Stir at a stirring speed of 500 r / min at a temperature of 35°C for 30 min, then add the modified silica in S3, and stir at the original stirring speed at a temperature of 100°C for 5 h. The obtained product is recorded as nano-organic boron cross-linking component;

[0056] S5. Add 3 parts by weight of potassium chloride to 100 parts by weight of deionized water, stir at a stirring speed of 800 r / min for 10 min, then add 8 parts by weight of the modified hydroxypropyl guar gum in S2 and 3 parts by weight of the self-made carboxymethyl hydroxypropyl guar gum, stir at the original stirring speed for 10 min, and then place it at a temperature of 30 °C for 4 h. The obtained product is denoted as the pre-crosslinked component;

[0057] S6. Add a nano-organic boron crosslinking component with a weight of 5% of it and a self-made gel polymer with a weight of 3% of it to the pre-crosslinked component in S5, and stir at high speed for 3 min. The obtained product is the acidic gelling agent for oil recovery.

[0058] The mass fraction of the ethanol aqueous solution in S1 is 60%, and the stirring speed in S1 is 400 r / min.

[0059] The mass fraction of the ethanol aqueous solution in S2 is 80%, the mass fraction of the sodium hydroxide solution in S2 is 2%, the drying temperature in S2 is 50 °C, and the drying time is 24 h.

[0060] The preparation method of the nano-silica in S3 is as follows: Mix 5 parts by weight of ammonia water and 50 parts by weight of absolute ethanol, stir at a stirring speed of 1000 r / min for 30 min, then add 3 parts by weight of tetraethyl orthosilicate, then stir at a stirring speed of 600 r / min for 24 h, wash 3 times with absolute ethanol, place it in an oven at 55 °C to dry, and then grind it through a 200-mesh sieve. The obtained product is the nano-silica.

[0061] The preparation method of the self-made carboxymethyl hydroxypropyl guar gum in S5 is as follows: Weigh 10 parts by weight of guar gum flakes and 100 parts by weight of tetrahydrofuran and pour them into a flask. Adjust the pH value to 9 with a sodium hydroxide solution and react at a temperature of 25 °C for 50 min, then dropwise add 4 parts by weight of sodium chloroacetate solution and react for 30 min, then dropwise add 5 parts by weight of propylene oxide, carry out a condensation reflux reaction at a temperature of 45 °C, react for 4 h, neutralize to neutral with glacial acetic acid, and finally wash with absolute ethanol and place it in an oven at 50 °C to dry. The obtained product is the self-made carboxymethyl hydroxypropyl guar gum.

[0062] In the preparation method of the self-made carboxymethyl hydroxypropyl guar gum, the mass fraction of the sodium hydroxide solution is 40%, and the mass fraction of the sodium chloroacetate solution is 20%.

[0063] The preparation method of the self-made gel polymer in S6 includes the following steps:

[0064] Step 1. Weigh 8 parts by weight of 2-acrylamide-2-methylpropanesulfonic acid and 50 parts by weight of deionized water and mix them. Adjust the pH value to 7, then add 5 parts by weight of acrylamide and 2 parts by weight of dimethyldiallylammonium chloride, and react for 30 min under a nitrogen atmosphere. The obtained product is denoted as the mixed component;

[0065] Step 2: Add an initiator component with a weight of 0.3% of the mixed components in Step 1, continue to react for 10 min under a nitrogen atmosphere condition and then seal, react for 5 h under a temperature condition of 40 °C, pour the product into isopropyl alcohol after the reaction is completed, wash it 3 times with absolute ethanol and then dry it, grind it through a 100-mesh sieve, and the obtained product is the self-made gel polymer.

[0066] The initiator component is prepared by mixing potassium persulfate and sodium bisulfite in a weight ratio of 2:1.

[0067] The stirring speed of high-speed stirring in S6 is 1000 r / min.

[0068] An acidic gelling agent for oil extraction, the raw materials of the acidic gelling agent for oil extraction include the following components: oleic acid amide propyl dimethyl tertiary amine, an ethanol aqueous solution with a mass fraction of 60%, glacial acetic acid, hydroxypropyl guar gum powder, an ethanol aqueous solution with a mass fraction of 80%, a sodium hydroxide solution with a mass fraction of 2%, absolute ethanol, ammonia water, tetraethyl orthosilicate, 3-aminopropyltriethoxysilane, n-butanol, ethylene glycol, boric acid, potassium chloride, guanidine film, tetrahydrofuran, a sodium hydroxide solution with a mass fraction of 40%, a sodium chloroacetate solution with a mass fraction of 20%, propylene oxide, 2-acrylamide-2-methylpropanesulfonic acid, acrylamide, dimethyldiallylammonium chloride, potassium persulfate, sodium bisulfite and isopropyl alcohol.

[0069] Example 3

[0070] The preparation method of an acidic gelling agent for oil extraction in this example is as follows:

[0071] S1: Weigh 31 parts by weight of oleic acid amide propyl dimethyl tertiary amine and 53 parts by weight of ethanol aqueous solution and pour them into a three-necked flask. Add glacial acetic acid to adjust the pH value to 6 under stirring conditions, then add 11 parts by weight of epichlorohydrin under a water bath condition of 60 °C, and record the obtained product as the intermediate component after reacting for 4 h.

[0072] S2: Mix 3 parts by weight of hydroxypropyl guar gum powder and 33 parts by weight of ethanol aqueous solution, then add sodium hydroxide solution to adjust the pH value to 8, alkalize for 42 min under a temperature condition of 25 °C, and dropwise add the intermediate component in S1 under a water bath condition of 80 °C. After reacting for 4 h, obtain the product, wash it 3 times with absolute ethanol, and record the obtained product as the modified hydroxypropyl guar gum after suction filtration and drying.

[0073] S3. Weigh 6 parts by weight of nano-silica dioxide and pour it into 53 parts by weight of absolute ethanol. Ultrasonically disperse it for 30 min at a frequency of 24 kHz, then add 5 parts by weight of 3-aminopropyltriethoxysilane. After refluxing for 12 h, remove the absolute ethanol by rotary evaporation. The obtained product is denoted as modified silica dioxide;

[0074] S4. Weigh 9 parts by weight of n-butanol, 17 parts by weight of ethylene glycol and 7 parts by weight of boric acid and mix them. Stir at a stirring speed of 500 r / min at a temperature of 35 °C for 30 min. Then add the modified silica dioxide in S3 and stir at the original stirring speed at a temperature of 100 °C for 4 h. The obtained product is denoted as nano-organic boron cross-linking component;

[0075] S5. Add 3 parts by weight of potassium chloride to 100 parts by weight of deionized water. Stir at a stirring speed of 700 r / min for 10 min, then add 7 parts by weight of the modified hydroxypropyl guar gum in S2 and 3 parts by weight of self-made carboxymethyl hydroxypropyl guar gum. Stir at the original stirring speed for 10 min and then place it at a temperature of 30 °C for 4 h. The obtained product is denoted as pre-cross-linked component;

[0076] S6. Add the nano-organic boron cross-linking component with a weight of 5% of that in S5 and the self-made gel polymer with a weight of 3% of that in S5 to the pre-cross-linked component in S5. Stir at high speed for 3 min. The obtained product is the acidic gelling agent for oil exploitation.

[0077] The mass fraction of the ethanol aqueous solution in S1 is 60%, and the stirring speed in S1 is 400 r / min.

[0078] The mass fraction of the ethanol aqueous solution in S2 is 80%, the mass fraction of the sodium hydroxide solution in S2 is 2%, the drying temperature in S2 is 50 °C, and the drying time is 24 h.

[0079] The preparation method of the nano-silica dioxide in S3 is as follows: Mix 5 parts by weight of ammonia water and 50 parts by weight of absolute ethanol. Stir at a stirring speed of 900 r / min for 30 min, then add 3 parts by weight of tetraethyl orthosilicate. Then stir at a stirring speed of 600 r / min for 24 h, wash it 3 times with absolute ethanol, place it in an oven at 55 °C to dry, and grind it through a 200-mesh sieve. The obtained product is nano-silica dioxide.

[0080] The preparation method of the self-made carboxymethyl hydroxypropyl guar gum in S5 is as follows: Weigh 10 parts by weight of guar gum flakes and 100 parts by weight of tetrahydrofuran and pour them into a flask. After adjusting the pH value to 9 with sodium hydroxide solution, react at a temperature of 25 °C for 50 min, then dropwise add 4 parts by weight of sodium chloroacetate solution and react for 30 min. Then dropwise add 5 parts by weight of propylene oxide and carry out a condensation reflux reaction at a temperature of 45 °C. After reacting for 4 h, neutralize to neutral with glacial acetic acid. Finally, wash with absolute ethanol and dry at a temperature of 50 °C. What is obtained is the self-made carboxymethyl hydroxypropyl guar gum.

[0081] In the preparation method of the self-made carboxymethyl hydroxypropyl guar gum, the mass fraction of the sodium hydroxide solution is 40%, and the mass fraction of the sodium chloroacetate solution is 20%.

[0082] The preparation method of the self-made colloid polymer in S6 includes the following steps:

[0083] Step 1: Weigh 8 parts by weight of 2-acrylamido-2-methylpropanesulfonic acid and 50 parts by weight of deionized water and mix them. After adjusting the pH value to 7, add 5 parts by weight of acrylamide and 2 parts by weight of dimethyldiallylammonium chloride, and react for 30 min under a nitrogen atmosphere. What is obtained is denoted as the mixed component;

[0084] Step 2: Add an initiator component with a weight of 0.3% of that in Step 1 to the mixed component in Step 1, continue to react for 10 min under a nitrogen atmosphere and then seal, and react at a temperature of 40 °C for 4 h. After the reaction is completed, pour it into isopropyl alcohol to obtain a white product. Wash it 3 times with absolute ethanol and then dry, grind it through a 100-mesh sieve. What is obtained is the self-made colloid polymer.

[0085] The initiator component is prepared by mixing potassium persulfate and sodium bisulfite in a weight ratio of 2:1.

[0086] The stirring speed of the high-speed stirring in S6 is 900 r / min.

[0087] An acidic gelling agent for oil exploitation, the raw materials of the acidic gelling agent for oil exploitation include the following components: oleic acid amide propyl dimethyl tertiary amine, ethanol aqueous solution with a mass fraction of 60%, glacial acetic acid, hydroxypropyl guar gum powder, ethanol aqueous solution with a mass fraction of 80%, sodium hydroxide solution with a mass fraction of 2%, absolute ethanol, ammonia water, tetraethyl orthosilicate, 3-aminopropyltriethoxysilane, n-butanol, ethylene glycol, boric acid, potassium chloride, guar gum flakes, tetrahydrofuran, sodium hydroxide solution with a mass fraction of 40%, sodium chloroacetate solution with a mass fraction of 20%, propylene oxide, 2-acrylamido-2-methylpropanesulfonic acid, acrylamide, dimethyldiallylammonium chloride, potassium persulfate, sodium bisulfite, and isopropyl alcohol.

[0088] Comparative Example 1

[0089] A kind of acidic gelling agent for oil extraction and its preparation method provided in this comparative example are generally the same as those in Example 1, and the main difference lies in that: in the preparation method of Comparative Example 1, the modified hydroxypropyl guar gum in Example 1 was not added.

[0090] Comparative Example 2

[0091] A kind of acidic gelling agent for oil extraction and its preparation method provided in this comparative example are generally the same as those in Example 1, and the main difference lies in that: in the preparation method of Comparative Example 2, the self-made carboxymethyl hydroxypropyl guar gum in Example 1 was not added.

[0092] Comparative Example 3

[0093] A kind of acidic gelling agent for oil extraction and its preparation method provided in this comparative example are generally the same as those in Example 1, and the main difference lies in that: in the preparation method of Comparative Example 3, the self-made gelling polymer in Example 1 was not added.

[0094] Performance Test

[0095] The acidic gelling agents for oil extraction prepared in Examples 1 - 3 were respectively marked as Example 1, Example 2, and Example 3, and the acidic gelling agents for oil extraction prepared in Comparative Examples 1 - 3 were respectively marked as Comparative Example 1, Comparative Example 2, and Comparative Example 3. Then, the viscosities of Examples 1 - 3 and Comparative Examples 1 - 3 at different temperatures were detected, and the specific detection data are recorded in the following table:

[0096]

[0097] It can be seen from the data in the above table that the viscosities of the acidic gelling agents for oil extraction in Examples 1 - 3 of the present invention are higher, indicating that the modified hydroxypropyl guar gum, self-made carboxymethyl hydroxypropyl guar gum, and self-made gelling polymer added in the present invention can play a role in increasing the viscosity of the acidic gelling agent; as the temperature rises, the viscosities of the acidic gelling agents for oil extraction in Examples 1 - 3 of the present invention are always higher than those of the acidic gelling agents for oil extraction in Comparative Examples 1 - 3, indicating that the acidic gelling agent prepared by the present invention has good thermal stability and can still maintain good viscosity at a temperature of 180 °C, and can be better applied to oil extraction operations.

[0098] In summary, the acidic gelling agent for oil extraction prepared by the present invention has excellent market application value and broader market application prospects.

[0099] It should be noted that in this text, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the phrase "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or device comprising said element.

[0100] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements will not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A preparation method of an acidic gelling agent for oil extraction, characterized in that, The preparation method is as follows: S1. Weigh 30 - 32 parts by weight of oleamide propyl dimethyl tertiary amine and 50 - 55 parts by weight of ethanol aqueous solution and pour them into a three - necked flask. Under stirring conditions, add glacial acetic acid to adjust the pH value to 5 - 6. Then, add 10 - 12 parts by weight of epichlorohydrin under a water bath condition of 60 °C. After reacting for 3 - 4 h, the obtained product is denoted as the intermediate component; S2. Mix 3 - 4 parts by weight of hydroxypropyl guar gum powder and 30 - 35 parts by weight of ethanol aqueous solution. Then, add sodium hydroxide solution to adjust the pH value to 8. Alkalize at a temperature of 25 °C for 40 - 45 min. Under a water bath condition of 80 °C, dropwise add the intermediate component in S1. After reacting for 3 - 4 h, the product is obtained. Wash it 3 times with absolute ethanol, and after suction filtration and drying, the obtained product is denoted as modified hydroxypropyl guar gum; S3. Weigh 6 - 7 parts by weight of nano - silica and pour it into 50 - 55 parts by weight of absolute ethanol. Ultrasonically disperse it at a frequency of 23 - 25 kHz for 30 min. Then, add 5 - 6 parts by weight of 3 - aminopropyltriethoxysilane. After refluxing for 12 h, remove absolute ethanol by rotary evaporation. The obtained product is denoted as modified silica; S4. Weigh 8 - 10 parts by weight of n - butanol, 15 - 18 parts by weight of ethylene glycol and 6 - 8 parts by weight of boric acid and mix them. Stir at a stirring speed of 400 - 500 r / min at a temperature of 35 °C for 30 min. Then, add the modified silica in S3. Stir at the original stirring speed at a temperature of 100 °C for 4 - 5 h. The obtained product is denoted as nano - organic boron cross - linked component; S5. Add 2 - 3 parts by weight of potassium chloride to 100 parts by weight of deionized water. Stir at a stirring speed of 600 - 800 r / min for 10 min. Then, add 5 - 8 parts by weight of the modified hydroxypropyl guar gum in S2 and 2 - 3 parts by weight of self - made carboxymethyl hydroxypropyl guar gum. Stir at the original stirring speed for 10 min and then place it at a temperature of 30 °C for 4 h. The obtained product is denoted as pre - cross - linked component; S6. Add the nano - organic boron cross - linked component with a weight of 5% of that in S5 and the self - made gel polymer with a weight of 3% of that in S5 to the pre - cross - linked component in S5. Stir at high speed for 3 min. The obtained product is the acidic gelling agent for oil exploitation; The preparation method of the self - made gel polymer in S6 includes the following steps: Step 1. Weigh 8 parts by weight of 2 - acrylamide - 2 - methylpropane sulfonic acid and 50 parts by weight of deionized water and mix them. Adjust the pH value to 7, then add 5 parts by weight of acrylamide and 2 parts by weight of dimethyldiallylammonium chloride. React under a nitrogen atmosphere for 30 min. The obtained product is denoted as the mixed component; Step 2. Add the initiator component with a weight of 0.3% of that in Step 1 to the mixed component in Step 1. Continue to react under a nitrogen atmosphere for 10 min and then seal. React at a temperature of 40 °C for 4 - 5 h. After the reaction is completed, pour it into isopropanol to obtain a white product. Wash it 3 times with absolute ethanol and then dry it. Grind it through a 100 - mesh sieve. The obtained product is the self - made gel polymer.

2. The preparation method of an acidic gelling agent for oil extraction according to claim 1, characterized in that, In S1, the mass fraction of the ethanol aqueous solution is 60%, and the stirring speed of the stirring in S1 is 300 - 400 r / min.

3. The preparation method of an acidic gelling agent for oil exploitation according to claim 1, characterized in that, The mass fraction of the ethanol aqueous solution in S2 is 80%, the mass fraction of the sodium hydroxide solution in S2 is 2%, the drying temperature of the drying in S2 is 50 °C, and the drying time is 24 h.

4. The preparation method of an acidic gelling agent for oil extraction according to claim 1, characterized in that, The preparation method of the nano-silica in S3 is as follows: Mix 5 parts by weight of ammonia water and 50 parts by weight of absolute ethanol, stir at a stirring speed of 800 - 1000 r / min for 30 min, then add 3 parts by weight of tetraethyl orthosilicate, and then stir at a stirring speed of 500 - 600 r / min for 24 h, wash 3 times with absolute ethanol, dry in an oven at 55 °C, and then grind through a 200-mesh sieve. What is obtained is the nano-silica.

5. The preparation method of an acidic gelling agent for oil extraction according to claim 1, characterized in that, The preparation method of the self-made carboxymethyl hydroxypropyl guar gum in S5 is as follows: Weigh 10 parts by weight of guar gum flakes and 100 parts by weight of tetrahydrofuran and pour them into a flask. Adjust the pH value to 9 with a sodium hydroxide solution and react at a temperature of 25 °C for 50 min. Then, dropwise add 4 parts by weight of sodium chloroacetate solution and react for 30 min. Then, dropwise add 5 parts by weight of propylene oxide and carry out a condensation reflux reaction at a temperature of 45 °C. After reacting for 4 h, neutralize to neutral with glacial acetic acid. Finally, wash with absolute ethanol and dry at a temperature of 50 °C. What is obtained is the self-made carboxymethyl hydroxypropyl guar gum.

6. The preparation method of an acidic gelling agent for oil exploitation according to claim 5, characterized in that, In the preparation method of the self-made carboxymethyl hydroxypropyl guar gum, the mass fraction of the sodium hydroxide solution is 40%, and the mass fraction of the sodium chloroacetate solution is 20%.

7. The preparation method of an acidic gelling agent for oil extraction according to claim 1, characterized in that, The initiator component is prepared by mixing potassium persulfate and sodium bisulfite in a weight ratio of 2:

1.

8. The preparation method of an acidic gelling agent for oil extraction according to claim 1, characterized in that, The stirring speed of the high-speed stirring in S6 is 800 - 1000 r / min.

9. An acid gelling agent for oil exploitation prepared by the preparation method of an acid gelling agent for oil exploitation according to any one of claims 1-8, characterized in that, The raw materials of the acidic gelling agent for oil exploitation include the following components: oleic acid amide propyl dimethyl tertiary amine, ethanol aqueous solution with a mass fraction of 60%, glacial acetic acid, hydroxypropyl guar gum powder, ethanol aqueous solution with a mass fraction of 80%, sodium hydroxide solution with a mass fraction of 2%, absolute ethanol, ammonia water, tetraethyl orthosilicate, 3-aminopropyltriethoxysilane, n-butanol, ethylene glycol, boric acid, potassium chloride, guar gum flakes, tetrahydrofuran, sodium hydroxide solution with a mass fraction of 40%, sodium chloroacetate solution with a mass fraction of 20%, propylene oxide, 2-acrylamide-2-methylpropanesulfonic acid, acrylamide, dimethyldiallylammonium chloride, potassium persulfate, sodium bisulfite, and isopropanol.

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