Small cation clay stabilizer as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of petrochemical engineering, and particularly relates to a small cation clay stabilizer as well as a preparation method and application thereof. The small cationic clay stabilizer comprises the following components: cationic quaternary ammonium salt, organic ammonium salt and water, and the number of carbon atoms of the cationic quaternary ammonium salt is 25-40. The small cation clay stabilizer solves the problems that an inorganic salt clay stabilizer is insufficient in long-term effect, an organic cation quaternary ammonium salt clay stabilizer has a large influence on the viscosity of a fracturing fluid base fluid and the like, on the basis that the anti-swelling rate is kept to be larger than or equal to 90%, the washing resistance of the clay stabilizer is greatly improved, the washing resistance is larger than or equal to 85%, and the anti-swelling rate is larger than or equal to 90%. The influence on the viscosity of the fracturing fluid is reduced; the influence on the performance of the fracturing fluid is small, the apparent viscosity reduction amplitude of the fracturing fluid is smaller than or equal to 15%, the viscosity retention rate of the gel fracturing fluid is larger than or equal to 90%, and good application prospects are achieved.

Description

Technical Field

[0001] This invention belongs to the field of petrochemical technology, specifically relating to a small cationic clay stabilizer, its preparation method, and its application. Background Technology

[0002] Fracturing is the primary method for increasing oil and gas reservoir production. However, when water-sensitive minerals in the reservoir come into contact with water-based fracturing fluids, they undergo irreversible swelling and migration, leading to pore throat blockage and decreased reservoir permeability, severely impacting oil recovery efficiency. To protect the permeability of oil and gas formations, chemical treatment agents must be used to stabilize clay minerals in the formation. Agents that prevent the swelling and migration of clay minerals are called clay stabilizers. Clay stabilizers prevent swelling of expansive clays such as montmorillonite from the repulsion phenomenon caused by the replacement of surface cations with hydrogen ions from water, forming a diffused double layer, which results in the expansion of the clay.

[0003] Existing clay stabilizers are mainly classified into three categories: inorganic salts, cationic surfactants, and organic cationic polymers. Among them, inorganic salts, as clay stabilizers, lack long-term effectiveness. During oil extraction, their clay-stabilizing effect disappears when their concentration decreases to a certain level. Furthermore, these clay stabilizers cannot generate multi-point adsorption, thus their effect on preventing clay migration is not significant. Cationic surfactants can dissociate into surface-active cations in water, which can adsorb onto the surface of clay particles and neutralize the negative charge on the clay surface. However, when used as clay anti-swelling agents, cationic surfactants are prone to react with other anionic chemical agents to produce precipitation. Their biggest drawback is that they change the water wettability of the reservoir to oil wettability, leading to a decrease in the relative permeability of water. Organic cationic polymers are polymers containing nitrogen, sulfur, and phosphorus. Polyquaternary ammonium salts are commonly used. They dissociate in water to generate high-positive-valence high-molecular-weight cations, which can simultaneously form multi-point adsorption with multiple clay particles. After adsorption, an adsorption protective film is formed on the surface of the clay particles, preventing the expansion and migration of the clay particles.

[0004] Chinese invention patent application CN117304400A discloses a high-temperature resistant clay stabilizer and its preparation method. The method involves adding N,N-bis(2-hydroxyethyl)methacrylamide, aminosulfonic acid powder, and urea to a four-necked flask, stirring and heating the mixture while maintaining the temperature for the reaction. Then, distilled water, (3-acrylamidopropyl)trimethylammonium chloride, 2-methacryloyloxyethyl phosphocholine, and a buffer salt are added sequentially to the same four-necked flask, and the mixture is stirred until homogeneous. An initiator is then added dropwise to the flask, causing the system to automatically heat up and maintain the temperature for the reaction. The reaction is terminated by adding potassium dimethyl dithiocarbamate solution, adjusting the pH, and cooling the mixture to below 40°C to obtain a viscous liquid. The viscous liquid is then dried and granulated to obtain the clay stabilizer product.

[0005] Another Chinese invention patent application, CN104098738A, discloses a method for preparing a low molecular weight clay stabilizer. This clay stabilizer is prepared by polymerizing an ammonium salt containing carbon and 2-acrylamido-2-methylpropanesulfonic acid (AMPS) in an aqueous solution in the presence of an initiator. The number average molecular weight of the polymer is less than 50,000. The polymer stabilizer introduces sulfonic acid groups, which increases the water solubility and temperature resistance of the polymer. The stabilizer has high temperature resistance, reaching above 120°C.

[0006] Another Chinese invention patent application, CN109456741A, discloses a clay stabilizer and its preparation method. The method involves copolymerizing 1-allyl-3-phenylthiourea with acrylamide and acryloyloxyethyltrimethylammonium chloride, and then compounding it with an h-PAMAM type guanidine salt compound to prepare a composite clay stabilizer. This stabilizer effectively inhibits the hydration and swelling of clay particles, with an anti-swelling rate of over 90%, and the anti-swelling rate remains over 80% even after four washes.

[0007] While the above-mentioned clay stabilizers have a good inhibitory effect, they also have some problems: (1) The small molecule quaternary ammonium salts used have small molecular weights. Although they can enter the clay lamellae, they cannot effectively pull the adjacent clay particles together to keep them in a larger particle state. They have poor water washing resistance and insufficient long-term effect. (2) The polymer-type large cationic polymer fracturing fluids used in field applications are mostly thickened with anionic polyacrylamide. In the unconventional shale gas fracturing process, the thickening agent used in large-scale drag-reducing water fracturing fluids is ultra-high molecular weight anionic polyacrylamide. In this case, the addition of cationic clay stabilizers will cause the thickener to flocculate and precipitate. At the same time, due to the large molecular weight, it is not suitable for low-permeability formations and is easy to form plugs in the formation pore channels, thereby blocking the formation.

[0008] Therefore, there is an urgent need in this field to develop a long-lasting clay stabilizer with low molecular weight, excellent anti-swelling properties, strong water-washing resistance, and good compatibility with other treatment agents, in order to meet the growing demand of the fracturing fluid market and improve production efficiency. Summary of the Invention

[0009] This invention addresses the problems existing in the prior art by providing a small cationic clay stabilizer, its preparation method, and its application.

[0010] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0011] A small cationic clay stabilizer comprises the following components: a cationic quaternary ammonium salt, an organic ammonium salt, and water.

[0012] Preferably, the cation quaternary ammonium salt has 25-40 carbon atoms.

[0013] More preferably, the cationic quaternary ammonium salt is selected from one or more of dodecyl dimethyl ammonium chloride, tetraheptyl ammonium chloride, methyl trioctyl ammonium chloride, and tetraoctyl ammonium chloride.

[0014] Preferably, the organic ammonium salt is selected from one or more of choline chloride, dimethyl diallyl ammonium chloride, octadecyl dimethyl trimethylsilyl ammonium chloride, and trimethyl allyl ammonium chloride.

[0015] More preferably, the organic ammonium salt is dimethyl diallyl ammonium chloride or trimethyl allyl ammonium chloride.

[0016] Preferably, by mass parts, it comprises the following components: 60-90 parts of cationic quaternary ammonium salt, 0-20 parts of organic ammonium salt, 0-10 parts of inorganic salt, and 5-15 parts of water.

[0017] More preferably, by mass parts, it comprises the following components: 75-85 parts of cationic quaternary ammonium salt, 10-20 parts of organic ammonium salt, 0-5 parts of inorganic salt and 5-10 parts of water.

[0018] More preferably, by mass parts, it comprises the following components: 80 parts of cationic quaternary ammonium salt, 10 parts of organic ammonium salt, and 10 parts of water.

[0019] Preferably, the inorganic salt is potassium chloride or ammonium chloride.

[0020] The present invention also provides a method for preparing the above-mentioned small cationic clay stabilizer, comprising the following steps: mixing cationic quaternary ammonium salt, organic ammonium salt and inorganic salt with water to obtain the stabilizer.

[0021] The present invention also provides the application of the above-mentioned small cationic clay stabilizer or the small cationic clay stabilizer prepared by the above preparation method in the preparation of fracturing fluid base fluid.

[0022] Preferably, the fracturing fluid base fluid comprises the following components: the above-mentioned small cationic clay stabilizer or the small cationic clay stabilizer prepared by the above preparation method, a thickener, a drainage aid, and water.

[0023] Preferably, the thickener is a polyacrylamide polymer, and the discharge aid is a fluorocarbon surfactant.

[0024] Preferably, the fracturing fluid base fluid comprises, by mass percentage: 0.2-0.8% small cationic clay stabilizer, 0.4-0.8% thickener, 0.2-0.8% drainage aid, and the balance water to make up to 100%.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The small cationic clay stabilizer of this invention solves the problems of insufficient long-term effectiveness of inorganic salt clay stabilizers and the significant impact of organic cationic quaternary ammonium salt clay stabilizers on the viscosity of fracturing fluid base fluid. While maintaining an anti-swelling rate of ≥90%, it significantly improves the water-washing resistance of the clay stabilizer, achieving a water-washing resistance of ≥85%, thus reducing its impact on the viscosity of fracturing fluid. It has minimal impact on the performance of fracturing fluid, with an apparent viscosity reduction of ≤15%, and a viscosity retention rate of ≥90% for gel fracturing fluid, demonstrating good application prospects. Detailed Implementation

[0027] It is worth noting that all raw materials used in this invention are commercially available products. Among them, didecyl dimethyl ammonium chloride, tetraheptyl ammonium chloride, methyl trioctyl ammonium chloride, and tetraoctyl ammonium chloride are all analytical grade and purchased from Maclean's Reagent Company; polyacrylamide polymer GAF-KY is purchased from Sichuan Guangya Polymer Chemical Co., Ltd.; organozirconium complex GAF-5A is purchased from Sichuan Guangya Polymer Chemical Co., Ltd.; fluorocarbon surfactant MJ-1 is purchased from Xinjiang Kang'en Industrial Petrochemical Co., Ltd.; 2% KCl is purchased from Aladdin; clay stabilizer ZGNW-013 is purchased from Karamay Ziguang Technology Co., Ltd.; and clay stabilizer OFC-610 is purchased from Shandong Aike Water Treatment Technology Co., Ltd.

[0028] Example 1

[0029] A small cationic clay stabilizer, by mass parts, is composed of the following raw materials:

[0030] Cationic quaternary ammonium salt: 80 parts of tetraheptylammonium chloride;

[0031] Organic ammonium salt: 10 parts of dimethyl diallyl ammonium chloride;

[0032] Water: 10 parts.

[0033] A method for preparing a small cationic clay stabilizer, comprising the following steps:

[0034] The cationic quaternary ammonium salt, organic ammonium salt, and water are mixed at 25°C to obtain the product.

[0035] Example 2

[0036] A small cationic clay stabilizer, by mass parts, is composed of the following raw materials:

[0037] Cationic quaternary ammonium salt: 70 parts of methyltrioctylammonium chloride;

[0038] Organic ammonium salt: 20 parts of dimethyl diallyl ammonium chloride;

[0039] Water: 10 parts.

[0040] A method for preparing a small cationic clay stabilizer, comprising the following steps:

[0041] The cationic quaternary ammonium salt, organic ammonium salt, and water are mixed at 25°C to obtain the product.

[0042] Example 3

[0043] A small cationic clay stabilizer, by mass parts, is composed of the following raw materials:

[0044] Cationic quaternary ammonium salt: 70 parts of dodecyl dimethyl ammonium chloride;

[0045] Organic ammonium salt: 10 parts of trimethylallyl ammonium chloride;

[0046] Inorganic salt: 10 parts ammonium chloride;

[0047] Water: 10 parts.

[0048] A method for preparing a small cationic clay stabilizer, comprising the following steps:

[0049] The product is obtained by mixing cationic quaternary ammonium salt, organic ammonium salt, inorganic salt and water at 25℃.

[0050] Example 4

[0051] A small cationic clay stabilizer, by mass parts, is composed of the following raw materials:

[0052] Cationic quaternary ammonium salt: 30 parts of dodecyl dimethyl ammonium chloride and 30 parts of tetraheptyl ammonium chloride;

[0053] Organic ammonium salt: 20 parts of trimethylallyl ammonium chloride;

[0054] Inorganic salts: 10 parts potassium chloride;

[0055] Water: 10 parts.

[0056] A method for preparing a small cationic clay stabilizer, comprising the following steps:

[0057] The product is obtained by mixing cationic quaternary ammonium salt, organic ammonium salt, inorganic salt and water at 25℃.

[0058] Example 5

[0059] A small cationic clay stabilizer, by mass parts, is composed of the following raw materials:

[0060] Cationic quaternary ammonium salts: 45 parts of methyltrioctylammonium chloride and 45 parts of tetraoctylammonium chloride;

[0061] Water: 10 parts.

[0062] A method for preparing a small cationic clay stabilizer, comprising the following steps:

[0063] The cationic quaternary ammonium salt is mixed with water at 25°C to obtain the product.

[0064] Example 6

[0065] A fracturing fluid base fluid, by mass percentage, is composed of the following raw materials:

[0066] Thickener: GAF-KY, a polyacrylamide polymer, 0.60 wt%;

[0067] Example 1 prepared small cationic clay stabilizer 1 0.50 wt%;

[0068] Discharge aid: Fluorocarbon surfactant MJ-1 0.50wt%;

[0069] The remaining amount is water, bringing the total to 100%.

[0070] A method for preparing a fracturing fluid-based fluid, comprising the following steps:

[0071] The thickener is mixed with water to obtain a thickener base solution; under stirring, the drainage aid and the small cationic clay stabilizer 1 prepared in Example 1 are added to the thickener base solution and mixed to obtain the final product.

[0072] Example 7

[0073] A fracturing fluid base fluid, by mass percentage, is composed of the following raw materials:

[0074] Thickener: GAF-KY, a polyacrylamide polymer, 0.60 wt%;

[0075] Example 2 prepared small cationic clay stabilizer 2 0.50 wt%;

[0076] Discharge aid: Fluorocarbon surfactant MJ-1 0.50wt%;

[0077] The remaining amount is water, bringing the total to 100%.

[0078] A method for preparing a fracturing fluid-based fluid, comprising the following steps:

[0079] The thickener is mixed with water to obtain a thickener base solution; under stirring, the drainage aid and the small cationic clay stabilizer 2 prepared in Example 2 are added to the thickener base solution and mixed to obtain the final product.

[0080] Example 8

[0081] A fracturing fluid base fluid, by mass percentage, is composed of the following raw materials:

[0082] Thickener: GAF-KY, a polyacrylamide polymer, 0.60 wt%;

[0083] Example 3 prepared small cationic clay stabilizer 3 0.50 wt%;

[0084] Discharge aid: Fluorocarbon surfactant MJ-1 0.50wt%;

[0085] The remaining amount is water, bringing the total to 100%.

[0086] A method for preparing a fracturing fluid-based fluid, comprising the following steps:

[0087] The thickener is mixed with water to obtain a thickener base solution; under stirring, the drainage aid and the small cationic clay stabilizer 3 prepared in Example 3 are added to the thickener base solution and mixed to obtain the final product.

[0088] Example 9

[0089] A gel fracturing fluid, by weight percentage, is composed of the following raw materials:

[0090] Thickener: GAF-KY, a polyacrylamide polymer, 0.60 wt%;

[0091] Crosslinking agent: 0.50 wt% of organozzirconium composite GAF-5A;

[0092] Example 1 prepared small cationic clay stabilizer 1 0.50 wt%;

[0093] Discharge aid: Fluorocarbon surfactant MJ-1 0.50wt%;

[0094] The remainder is water: 97.9 wt%.

[0095] A method for preparing a gel fracturing fluid, comprising the following steps:

[0096] (1) Mix the thickener with 97.4 wt% water to obtain the thickener base liquid; add the drainage aid and the small cationic clay stabilizer 1 prepared in Example 1 to the thickener base liquid under stirring, mix well to obtain the first base liquid (fracturing fluid base liquid);

[0097] (2) Then mix the crosslinking agent with 0.5 wt% water to obtain the second base liquid;

[0098] (3) Finally, mix the first base liquid and the second base liquid at a mass ratio of 99:1 to obtain the final product.

[0099] Example 10

[0100] A gel fracturing fluid, by weight percentage, is composed of the following raw materials:

[0101] Thickener: GAF-KY, a polyacrylamide polymer, 0.60 wt%;

[0102] Crosslinking agent: 0.50 wt% of organozzirconium composite GAF-5A;

[0103] Example 3 prepared small cationic clay stabilizer 3 0.50 wt%;

[0104] Discharge aid: Fluorocarbon surfactant MJ-1 0.50wt%;

[0105] The remainder is water: 97.9 wt%.

[0106] A method for preparing a gel fracturing fluid, comprising the following steps:

[0107] (1) Mix the thickener with 97.4 wt% water to obtain the thickener base liquid; add the drainage aid and the small cationic clay stabilizer 3 prepared in Example 3 to the thickener base liquid under stirring, mix well to obtain the first base liquid (fracturing fluid base liquid);

[0108] (2) Then mix the crosslinking agent with 0.5 wt% water to obtain the second base liquid;

[0109] (3) Finally, mix the first base liquid and the second base liquid at a mass ratio of 99:1 to obtain the final product.

[0110] Comparative Example 1

[0111] Same as Example 1, except that the cationic quaternary ammonium salt is 2-hydroxypropyltrimethylammonium chloride.

[0112] A small cationic clay stabilizer, by mass parts, is composed of the following raw materials:

[0113] Cationic quaternary ammonium salt: 80 parts of 2-hydroxypropyltrimethylammonium chloride;

[0114] Organic ammonium salt: 10 parts of dimethyl diallyl ammonium chloride;

[0115] Water: 10 parts.

[0116] A method for preparing a small cationic clay stabilizer, comprising the following steps:

[0117] The cationic quaternary ammonium salt, organic ammonium salt, and water are mixed at 25°C to obtain the product.

[0118] Comparative Example 2

[0119] Same as Example 1, except that the organic ammonium salt is replaced with the inorganic salt potassium chloride.

[0120] A small cationic clay stabilizer, by mass parts, is composed of the following raw materials:

[0121] Cationic quaternary ammonium salt: 80 parts of tetraheptylammonium chloride;

[0122] Inorganic salts: 10 parts potassium chloride;

[0123] Water: 10 parts.

[0124] A method for preparing a small cationic clay stabilizer, comprising the following steps:

[0125] The cationic quaternary ammonium salt, organic ammonium salt, and water are mixed at 25°C to obtain the product.

[0126] Comparative Example 3

[0127] Same as Example 1, except that the number of cationic quaternary ammonium salts is 50 parts.

[0128] A small cationic clay stabilizer, by mass parts, is composed of the following raw materials:

[0129] Cationic quaternary ammonium salt: 50 parts of tetraheptylammonium chloride;

[0130] Organic ammonium salt: 10 parts of dimethyl diallyl ammonium chloride;

[0131] Water: 40 portions.

[0132] A method for preparing a small cationic clay stabilizer, comprising the following steps:

[0133] The cationic quaternary ammonium salt, organic ammonium salt, and water are mixed at 25°C to obtain the product.

[0134] Comparative Example 4

[0135] Same as Example 6, except that the small cationic clay stabilizer 1 of Example 1 is not added.

[0136] A fracturing fluid base fluid, by mass percentage, is composed of the following raw materials:

[0137] Thickener: GAF-KY, a polyacrylamide polymer, 0.60 wt%;

[0138] Discharge aid: Fluorocarbon surfactant MJ-1 0.50wt%;

[0139] The remaining amount is water, bringing the total to 100%.

[0140] A method for preparing a fracturing fluid-based fluid, comprising the following steps:

[0141] Mix the thickener with water to obtain the thickener base solution; add the discharge aid to the thickener base solution while stirring, mix well, and the product is ready.

[0142] Comparative Example 5

[0143] Same as Example 6, except that the small cationic clay stabilizer 1 of Example 1 is replaced with 2% KCl.

[0144] A fracturing fluid base fluid, by mass percentage, is composed of the following raw materials:

[0145] Thickener: GAF-KY, a polyacrylamide polymer, 0.60 wt%;

[0146] 2% KCl 0.50wt%;

[0147] Discharge aid: Fluorocarbon surfactant MJ-1 0.50wt%;

[0148] The remaining amount is water, bringing the total to 100%.

[0149] A method for preparing a fracturing fluid-based fluid, comprising the following steps:

[0150] Mix the thickener with water to obtain the thickener base solution; add the discharge aid and 2% KCl to the thickener base solution while stirring, and mix well to obtain the final product.

[0151] Comparative Example 6

[0152] Same as Example 6, except that the small cationic clay stabilizer 1 of Example 1 is replaced with commercially available clay stabilizer ZGNW-013.

[0153] A fracturing fluid base fluid, by mass percentage, is composed of the following raw materials:

[0154] Thickener: GAF-KY, a polyacrylamide polymer, 0.60 wt%;

[0155] Commercially available clay stabilizer ZGNW-013 0.50wt%;

[0156] Discharge aid: Fluorocarbon surfactant MJ-1 0.50wt%;

[0157] The remaining amount is water, bringing the total to 100%.

[0158] A method for preparing a fracturing fluid-based fluid, comprising the following steps:

[0159] Mix the thickener with water to obtain the thickener base liquid; add the drainage aid and commercially available clay stabilizer OFC-610 to the thickener base liquid while stirring, mix well, and the product is ready.

[0160] Comparative Example 7

[0161] Same as Example 6, except that the small cationic clay stabilizer 1 of Example 1 is replaced with commercially available clay stabilizer YN-1.

[0162] A fracturing fluid base fluid, by mass percentage, is composed of the following raw materials:

[0163] Thickener: GAF-KY, a polyacrylamide polymer, 0.60 wt%;

[0164] Commercially available clay stabilizer YN-1 0.50wt%;

[0165] Discharge aid: Fluorocarbon surfactant MJ-1 0.50wt%;

[0166] The remaining amount is water, bringing the total to 100%.

[0167] A method for preparing a fracturing fluid-based fluid, comprising the following steps:

[0168] Mix the thickener with water to obtain the thickener base liquid; add the drainage aid and commercially available clay stabilizer ZGNW-013 to the thickener base liquid while stirring, mix well, and the product is ready.

[0169] Comparative Example 8

[0170] Same as Example 9, except that the small cationic clay stabilizer 1 of Example 1 is not added.

[0171] A gel fracturing fluid, by weight percentage, is composed of the following raw materials:

[0172] Thickener: GAF-KY, a polyacrylamide polymer, 0.60 wt%;

[0173] Crosslinking agent: 0.50 wt% of organozzirconium composite GAF-5A;

[0174] Discharge aid: Fluorocarbon surfactant MJ-1 0.50wt%;

[0175] The remainder is water: 98.4 wt%.

[0176] A method for preparing a gel fracturing fluid, comprising the following steps:

[0177] (1) Mix the thickener with 97.9 wt% water to obtain the thickener base liquid; add the drainage aid to the thickener base liquid under stirring, mix well, and obtain the first base liquid (fracturing fluid base liquid);

[0178] (2) Then mix the crosslinking agent with 0.5 wt% water to obtain the second base liquid;

[0179] (3) Finally, mix the first base liquid and the second base liquid at a mass ratio of 99:1 to obtain the final product.

[0180] Comparative Example 9

[0181] Same as Example 9, except that the small cationic clay stabilizer 1 of Example 1 is replaced with 2% KCl.

[0182] A gel fracturing fluid, by weight percentage, is composed of the following raw materials:

[0183] Thickener: GAF-KY, a polyacrylamide polymer, 0.60 wt%;

[0184] Crosslinking agent: 0.50 wt% of organozzirconium composite GAF-5A;

[0185] 2% KCl 0.50wt%;

[0186] Discharge aid: Fluorocarbon surfactant MJ-1 0.50wt%;

[0187] The remainder is water: 97.9 wt%.

[0188] A method for preparing a gel fracturing fluid, comprising the following steps:

[0189] (1) Mix the thickener with 97.4 wt% water to obtain the thickener base liquid; add the drainage aid and 2% KCl to the thickener base liquid under stirring, mix well to obtain the first base liquid (fracturing fluid base liquid);

[0190] (2) Then mix the crosslinking agent with 0.5 wt% water to obtain the second base liquid;

[0191] (3) Finally, mix the first base liquid and the second base liquid at a mass ratio of 99:1 to obtain the final product.

[0192] Comparative Example 10

[0193] Same as Example 9, except that the small cationic clay stabilizer 1 of Example 1 is replaced with commercially available clay stabilizer ZGNW-013.

[0194] A gel fracturing fluid, by weight percentage, is composed of the following raw materials:

[0195] Thickener: GAF-KY, a polyacrylamide polymer, 0.60 wt%;

[0196] Crosslinking agent: 0.50 wt% of organozzirconium composite GAF-5A;

[0197] Commercially available clay stabilizer ZGNW-013 0.50wt%;

[0198] Discharge aid: Fluorocarbon surfactant MJ-1 0.50wt%;

[0199] The remainder is water: 97.9 wt%.

[0200] A method for preparing a gel fracturing fluid, comprising the following steps:

[0201] (1) Mix the thickener with 97.4 wt% water to obtain the thickener base liquid; add the drainage aid and commercial clay stabilizer ZGNW-013 to the thickener base liquid under stirring, mix well to obtain the first base liquid (fracturing fluid base liquid);

[0202] (2) Then mix the crosslinking agent with 0.5 wt% water to obtain the second base liquid;

[0203] (3) Finally, mix the first base liquid and the second base liquid at a mass ratio of 99:1 to obtain the final product.

[0204] Comparative Example 11

[0205] Same as Example 9, except that the small cationic clay stabilizer 1 of Example 1 is replaced with commercially available clay stabilizer YN-1.

[0206] A gel fracturing fluid, by weight percentage, is composed of the following raw materials:

[0207] Thickener: GAF-KY, a polyacrylamide polymer, 0.60 wt%;

[0208] Crosslinking agent: 0.50 wt% of organozzirconium composite GAF-5A;

[0209] Commercially available clay stabilizer YN-1 0.50wt%;

[0210] Discharge aid: Fluorocarbon surfactant MJ-1 0.50wt%;

[0211] The remainder is water: 97.9 wt%.

[0212] A method for preparing a gel fracturing fluid, comprising the following steps:

[0213] (1) Mix the thickener with 97.4 wt% water to obtain the thickener base liquid; add the drainage aid and commercial clay stabilizer YN-1 to the thickener base liquid under stirring, mix well to obtain the first base liquid (fracturing fluid base liquid);

[0214] (2) Then mix the crosslinking agent with 0.5 wt% water to obtain the second base liquid;

[0215] (3) Finally, mix the first base liquid and the second base liquid at a mass ratio of 99:1 to obtain the final product.

[0216] Test Example 1

[0217] The anti-swelling rate and water wash resistance of the small cationic clay stabilizers prepared in Examples 1-5 and Comparative Examples 1-3 were determined and compared with commercially available clay stabilizers 2% KCl, ZGNW-013 and YN-1. The test methods for anti-swelling rate and water wash resistance were all in accordance with "SY / T5971-2016 Performance Evaluation Method of Clay Stabilizers for Fracturing, Acidizing and Water Injection in Oil and Gas Fields".

[0218] The test results are shown in Table 1.

[0219] Table 1. Test data of the small cationic clay stabilizers prepared in Examples 1-5 and Comparative Examples 1-3.

[0220] Serial Number Anti-expansion rate (%) Water wash resistance (%) 2% KCl 94.6 67.3 ZGNW-013 73.9 61.2 YN-1 67.5 58.3 Example 1 96.5 93.6 Example 2 96.1 92.3 Example 3 96.4 91.6 Example 4 92.6 83.6 Example 5 94.4 82.4 Comparative Example 1 91.4 78.6 Comparative Example 2 94.3 89.6 Comparative Example 3 84.2 78.6

[0221] Analysis of the relevant data in Table 1 shows that the small cationic clay stabilizer provided in Example 1 of this invention is the best, with the highest anti-swelling rate and water washability.

[0222] As can be seen from Example 1 and Comparative Example 1, the addition of small molecule multi-branched cationic quaternary ammonium salts (C25-C40) can improve water washability.

[0223] As can be seen from Example 1 and Comparative Example 2, organic ammonium salts can work synergistically with other components to improve anti-swelling rate and water washability.

[0224] As can be seen from Example 1 and Comparative Example 3, reducing the dosage of small molecule multi-branched cationic quaternary ammonium salt (C25-C40) will weaken the anti-swelling rate and water washability.

[0225] Test Example 2

[0226] The apparent viscosity of the fracturing fluid base fluids prepared in Examples 6-8 and Comparative Examples 4-7 was measured respectively. The test method for apparent viscosity was in accordance with "SY / T 7627-2021 Technical Requirements for Water-based Fracturing Fluids".

[0227] The test results are shown in Table 2.

[0228] Table 2 Test data of fracturing fluid base fluids prepared in Examples 6-8 and Comparative Examples 4-7

[0229] Serial Number Apparent viscosity (mPa·s) Example 6 79.3 Example 7 73.6 Example 8 70.6 Comparative Example 4 82.2 Comparative Example 5 68.3 Comparative Example 6 36.4 Comparative Example 7 56.1

[0230] Test Example 3

[0231] The temperature and shear resistance properties of the gel fracturing fluids prepared in Examples 9-10 and Comparative Examples 8-11 were determined. The test methods for temperature and shear resistance properties were in accordance with the "SY / T 5107-2016 Performance Evaluation Method of Water-based Fracturing Fluids".

[0232] The test results are shown in Table 3.

[0233] Table 3 Test data of the gel fracturing fluids prepared in Examples 9-10 and Comparative Examples 8-11

[0234]

[0235]

[0236] In summary, the clay stabilizer of this invention is formed by combining various small-molecule quaternary ammonium salts, small-molecule organic ammonium salts, and inorganic salts. This significantly improves the water-wash resistance of the clay stabilizer while maintaining an anti-swelling rate of ≥95%. Even after three washes with distilled water, the anti-swelling rate still reaches over 90%. It has minimal impact on the performance of the fracturing fluid base fluid, with an apparent viscosity reduction of ≤15% and a viscosity retention rate of ≥90% for the gel fracturing fluid. This forms a small-cationic long-acting clay stabilizer system suitable for most reservoirs, meeting construction requirements and ensuring reservoir construction safety.

[0237] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, and is not intended to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions made by those skilled in the art to the technical solution of the present invention do not depart from the essence and scope of the technical solution of the present invention.

Claims

1. A small cationic clay stabilizer, characterized in that, It comprises the following components: a cationic quaternary ammonium salt, an organic ammonium salt, and water, wherein the cationic quaternary ammonium salt has 25-40 carbon atoms.

2. The small cationic clay stabilizer according to claim 1, characterized in that, The cationic quaternary ammonium salt is selected from one or more of dodecyl dimethyl ammonium chloride, tetraheptyl ammonium chloride, methyl trioctyl ammonium chloride, and tetraoctyl ammonium chloride.

3. The small cationic clay stabilizer according to claim 1, characterized in that, The organic ammonium salt is selected from one or more of choline chloride, dimethyl diallyl ammonium chloride, octadecyl dimethyl trimethylsilyl ammonium chloride, and trimethyl allyl ammonium chloride.

4. The small cationic clay stabilizer according to any one of claims 1-3, characterized in that, By mass, it comprises the following components: 60-90 parts of cationic quaternary ammonium salt, 0-20 parts of organic ammonium salt, 0-10 parts of inorganic salt, and 5-15 parts of water.

5. The small cationic clay stabilizer according to claim 4, characterized in that, The inorganic salt is potassium chloride or ammonium chloride.

6. A method for preparing a small cationic clay stabilizer as described in any one of claims 4-5, characterized in that, The process includes the following steps: mixing the cationic quaternary ammonium salt, organic ammonium salt, and inorganic salt with water to obtain the final product.

7. The application of a small cationic clay stabilizer as described in any one of claims 1-5 or a small cationic clay stabilizer prepared by the preparation method described in claim 6 in the preparation of fracturing fluid base fluid.

8. The application according to claim 7, characterized in that, The fracturing fluid base fluid comprises the following components: the small cationic clay stabilizer according to any one of claims 1-5 or the small cationic clay stabilizer prepared by the preparation method according to claim 6, a thickener, a drainage aid, and water.

9. The application according to claim 8, characterized in that, The thickener is a polyacrylamide polymer, and the drainage aid is a fluorocarbon surfactant.

10. The application according to claim 8, characterized in that, The fracturing fluid base fluid comprises, by mass percentage, the following components: 0.2-0.8% small cationic clay stabilizer, 0.4-0.8% thickener, 0.2-0.8% flow aid, and the balance water to make up to 100%.

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