Efficient multifunctional clay stabilizer for compact oil and gas reservoirs and preparation method of efficient multifunctional clay stabilizer

Abstract

The invention relates to the technical field of clay stabilizers, in particular to a high-efficiency multifunctional clay stabilizer for compact oil and gas reservoirs and a preparation method thereof.The high-efficiency multifunctional clay stabilizer is obtained through the following steps that a silane coupling agent and ethylene glycol are added into a hexamethylphosphoramide aqueous solution for a reaction, and after the pH value of the obtained product is adjusted, stirring is conducted to obtain a mixture; and adding a cationic surface active agent to continuously react. The efficient multifunctional clay stabilizer not only has lower surface tension and interfacial tension, can improve the surface wettability of clay and achieve neutral / weak hydrophilicity, has the effects of discharge aiding and imbibition / displacement, but also has higher anti-swelling effect and long-term effectiveness, and is suitable for compact oil and gas reservoirs.

Description

Technical Field

[0001] The invention relates to the technical field of clay stabilizers and is a high-efficiency multifunctional clay stabilizer for tight oil and gas reservoirs and a preparation method thereof. Background Art

[0002] The oil reservoir contains a large amount of clay minerals. Water molecules enter the crystal layers of clay minerals, causing the exchangeable cations in the crystal layers to dissociate and diffuse in the water, forming a diffuse double layer. Since the surface of the crystal layers is charged, they repel each other, causing the clay to swell, disperse and migrate, thereby blocking the pores of the formation and reducing the permeability of the oil layer. In order to protect the permeability of the oil and gas layer and increase the oil and gas production, clay stabilizers are added to various working fluids such as fracturing fluids, drilling fluids, and acidizing fluids to inhibit clay swelling.

[0003] Commonly used clay stabilizers are mainly inorganic salts, organic cations and high molecular polymers. Among them, inorganic salts have poor scouring resistance, and high molecular polymers have good water washing resistance because they can form multi-point adsorption, but their molecular chains are long and easy to block the pores of the reservoir, which is more harmful to tight gas reservoirs. Organic cationic quaternary ammonium salts are widely used in oil fields because of their good anti-swelling effect and small molecular weight. However, it is not strong enough to act on clay only by intermolecular forces or hydrogen bonds, and the water washing resistance is still limited. It is also easy to change the wettability of the rock surface into oil wettability, which is not conducive to oil and gas production. At the same time, if the rock surface is highly hydrophilic, it is not conducive to the return of the working fluid. The working fluid is retained in the formation, which is prone to water lock damage, causing reverse absorption of tiny capillary channels, thereby reducing the production of oil and gas. For tight oil and gas reservoirs, due to low permeability and small pore throat size, the capillary end effect is more obvious, resulting in more serious water lock damage. Summary of the invention

[0004] The present invention provides a high-efficiency multifunctional clay stabilizer for tight oil and gas reservoirs and a preparation method thereof, which overcomes the deficiencies of the above-mentioned prior art and can effectively solve the problems of the existing clay stabilizers such as poor long-term effectiveness, easy clogging of pore throats resulting in reduced reservoir permeability, and changing rock wettability resulting in reduced recovery rate.

[0005] One of the technical solutions of the present invention is achieved by the following measures: A high-efficiency multifunctional clay stabilizer for tight oil and gas reservoirs is obtained by the following method: S1, adding 25 to 30 parts of a silane coupling agent and 25 to 30 parts of ethylene glycol to 200 to 300 parts of an aqueous solution of hexamethylphosphoric triamide by mass under stirring, mixing to obtain a mixed solution, adjusting the pH of the mixed solution, and reacting to obtain a reaction product; S2, after adjusting the pH of the reaction product, 10 to 15 parts of a cationic surfactant are added to continue the reaction to obtain a high-efficiency multifunctional clay stabilizer.

[0006] The following is a further optimization and / or improvement of one of the above-mentioned technical solutions: The above-mentioned cationic surfactant is one or more of dodecyltrimethylammonium chloride, hexadecyltrimethylammonium chloride, hexadecyltrimethylammonium bromide, octadecyltrimethylammonium chloride, octadecyltrimethylammonium bromide, hexadecyltrimethylacetoxyammonium chloride, hexadecyltrimethylphenylammonium bromide and hexadecyltrimethylhydroxyethylammonium chloride.

[0007] The silane coupling agent is one or more of trimethyl[3-(trimethoxysilyl)propyl]ammonium chloride, aminosilane, butadienyltriethoxysilane and isobutyltriethoxysilane.

[0008] In the above step S1, the mass concentration of the hexamethylphosphoric triamide aqueous solution is 55% to 65%.

[0009] In the above step S1, during stirring, the stirring rate is 120 r / min to 150 r / min, the reaction temperature is 50° C. to 60° C., and the reaction time is 55 min to 60 min.

[0010] In the above step S1, a potassium hydroxide solution with a mass concentration of 10% is used to adjust the pH value of the mixed solution to 8.5 to 9.0.

[0011] In the above step S2, the pH value of the reaction product is adjusted to 5 to 6 with hydrochloric acid, and the reaction time is 30 min to 40 min.

[0012] The second technical solution of the present invention is achieved by the following measures: A method for preparing a high-efficiency multifunctional clay stabilizer for tight oil and gas reservoirs is carried out according to the following method: S1, adding 25 to 30 parts of a silane coupling agent and 25 to 30 parts of ethylene glycol to 200 to 300 parts of an aqueous solution of hexamethylphosphoric triamide by mass under stirring, mixing to obtain a mixed solution, adjusting the pH of the mixed solution, and reacting to obtain a reaction product; S2, after adjusting the pH of the reaction product, 10 to 15 parts of a cationic surfactant are added to continue the reaction to obtain a high-efficiency multifunctional clay stabilizer.

[0013] The high-efficiency multifunctional clay stabilizer of the present invention not only has low surface tension and interfacial tension, can improve the wettability of the clay surface, achieve neutral / weak hydrophilicity, has the functions of assisting drainage, imbibition / displacement, but also has high anti-swelling effect and long-term effectiveness, and is suitable for tight oil and gas reservoirs. DETAILED DESCRIPTION

[0014] The present invention is not limited by the following embodiments, and the specific implementation method can be determined according to the technical scheme of the present invention and the actual situation. Unless otherwise specified, the various chemical reagents and chemicals mentioned in the present invention are all chemical reagents and chemicals known and used in the prior art; unless otherwise specified, the percentages in the present invention are all mass percentages; unless otherwise specified, the solutions in the present invention are all aqueous solutions with water as the solvent, for example, hydrochloric acid solution is a hydrochloric acid aqueous solution; the normal temperature and room temperature in the present invention generally refer to a temperature of 15°C to 25°C, and are generally defined as 25°C.

[0015] The present invention will be further described below in conjunction with embodiments: Example 1: The high-efficiency multifunctional clay stabilizer for tight oil and gas reservoirs is obtained by the following method: S1, adding 25 to 30 parts of a silane coupling agent and 25 to 30 parts of ethylene glycol to 200 to 300 parts of an aqueous solution of hexamethylphosphoric triamide by mass under stirring, mixing to obtain a mixed solution, adjusting the pH of the mixed solution, and reacting to obtain a reaction product; S2, after adjusting the pH of the reaction product, 10 to 15 parts of a cationic surfactant are added to continue the reaction to obtain a high-efficiency multifunctional clay stabilizer.

[0016] Example 2: As an optimization of the above example, the cationic surfactant is one or more of dodecyltrimethylammonium chloride, hexadecyltrimethylammonium chloride, hexadecyltrimethylammonium bromide, octadecyltrimethylammonium chloride, octadecyltrimethylammonium bromide, hexadecyltrimethylacetoxyammonium chloride, hexadecyltrimethylphenylammonium bromide and hexadecyltrimethylhydroxyethylammonium chloride.

[0017] Example 3: As an optimization of the above example, the silane coupling agent is one or more of trimethyl[3-(trimethoxysilyl)propyl]ammonium chloride, aminosilane, butadienyltriethoxysilane and isobutyltriethoxysilane.

[0018] Example 4: As an optimization of the above example, in step S1, the mass concentration of the hexamethylphosphoric triamide aqueous solution is 55% to 65%.

[0019] Example 5: As an optimization of the above example, in step S1, during stirring, the stirring rate is 120 r / min to 150 r / min, the reaction temperature is 50°C to 60°C, and the reaction time is 55 min to 60 min.

[0020] Example 6: As an optimization of the above example, in step S1, a potassium hydroxide solution with a mass concentration of 10% is used to adjust the pH value of the mixed solution to 8.5 to 9.0.

[0021] Example 7: As an optimization of the above example, in step S2, the pH value of the reaction product is adjusted to 5 to 6 with hydrochloric acid, and the reaction time is 30 min to 40 min.

[0022] Embodiment 8: The high-efficiency multifunctional clay stabilizer for tight oil and gas reservoirs is obtained according to the following method: S1, adding 25 parts of silane coupling agent (trimethyl [3-(trimethoxysilyl)propyl] ammonium chloride, aminosilane) and 25 parts of ethylene glycol to 200 parts of a 55% aqueous solution of hexamethylphosphoric triamide by mass at a stirring rate of 120 r / min, and mixing to obtain a mixed solution, adjusting the pH value of the mixed solution to 8.5 with a 10% potassium hydroxide solution, and reacting at 50° C. for 55 min to obtain a reaction product; S2, after adjusting the pH value of the reaction product to 5 with hydrochloric acid, 10 parts of cationic surfactant (dodecyltrimethylammonium chloride) were added and the reaction was continued for 30 minutes to obtain a high-efficiency multifunctional clay stabilizer.

[0023] Embodiment 9: The high-efficiency multifunctional clay stabilizer for tight oil and gas reservoirs is obtained according to the following method: S1, adding 30 parts of silane coupling agent (butadienyl triethoxysilane) and 30 parts of ethylene glycol to 300 parts of a 65% hexamethylphosphoric triamide aqueous solution at a stirring rate of 150 r / min, mixing to obtain a mixed solution, adjusting the pH value of the mixed solution to 9.0 with a 10% potassium hydroxide solution, reacting at 60° C. for 60 minutes, and obtaining a reaction product; S2, after adjusting the pH value of the reaction product to 6 with hydrochloric acid, 15 parts of a cationic surfactant (hexadecyltrimethylammonium chloride) were added and the reaction was continued for 40 minutes to obtain a high-efficiency multifunctional clay stabilizer.

[0024] Embodiment 10: The high-efficiency multifunctional clay stabilizer for tight oil and gas reservoirs is obtained according to the following method: S1, adding 28 parts of silane coupling agent (isobutyl triethoxysilane) and 28 parts of ethylene glycol to 250 parts of a 60% hexamethylphosphoric triamide aqueous solution at a stirring rate of 130 r / min, and mixing to obtain a mixed solution, adjusting the pH value of the mixed solution to 8.7 with a 10% potassium hydroxide solution, and reacting at 55° C. for 58 minutes to obtain a reaction product; S2, after adjusting the pH value of the reaction product to 5.5 with hydrochloric acid, 12 parts of a cationic surfactant (octadecyltrimethylammonium chloride) were added and the reaction was continued for 35 minutes to obtain a high-efficiency multifunctional clay stabilizer.

[0025] Compared with the prior art, the present invention has the following beneficial effects: The present invention performs chain extension and modification reaction on the silane coupling agent. During the reaction process, the silicon in the molecular chain reacts chemically with the clay surface to form a stable covalent bond, and a condensation reaction occurs between the crystal layers inside the clay, connecting them with silicon-oxygen bonds. At the same time, since the quaternary ammonium group with a high positive charge in the cationic surfactant can be adsorbed on the negatively charged clay, the two produce a synergistic effect, locking the clay particles to prevent them from expanding, migrating and dispersing. Therefore, the anti-swelling effect and water-washing resistance of the high-efficiency multifunctional clay stabilizer for dense oil and gas reservoirs of the present invention can be significantly improved, making it efficient and durable.

[0026] In step S1 of the present invention, the reaction product obtained after the polymerization reaction of the silane coupling agent and ethylene glycol, due to the polyhydroxy alkyl chain in the reaction product can adjust the wettability of the clay surface to a neutral / weakly hydrophilic state (70°<contact angle<90°), coupled with its lower surface tension and interfacial tension, is conducive to the return of the working fluid and the imbibition-displacement effect, thereby reducing water lock damage and improving oil and gas recovery. In addition, since the quaternary ammonium group in the surfactant has a high positive charge, it can play a bactericidal and antibacterial role, and has a small molecular weight, it can be used in tight oil and gas reservoirs.

[0027] Embodiment 11: The high-efficiency multifunctional clay stabilizer for tight oil and gas reservoirs is obtained according to the following method: S1, adding 25 g of a silane coupling agent (trimethyl [3-(trimethoxysilyl)propyl] ammonium chloride) and 25 g of ethylene glycol to 200 g of a 65% aqueous solution of hexamethylphosphoric triamide at a stirring rate of 120 r / min, and mixing to obtain a mixed solution, adjusting the pH value of the mixed solution to 8.5 with a 10% potassium hydroxide solution, and reacting at 60° C. for 60 min to obtain a reaction product; S2, after adjusting the pH value of the reaction product to 5.5 with hydrochloric acid, 10 g of cationic surfactant (dodecyltrimethylammonium chloride) was added and the reaction was continued for 30 min to obtain a high-efficiency multifunctional clay stabilizer.

[0028] Embodiment 12: The high-efficiency multifunctional clay stabilizer for tight oil and gas reservoirs is obtained according to the following method: S1, adding 25 g of a silane coupling agent (trimethyl [3-(trimethoxysilyl)propyl] ammonium chloride) and 25 g of ethylene glycol to 200 g of a 65% aqueous solution of hexamethylphosphoric triamide at a stirring rate of 150 r / min, and mixing to obtain a mixed solution, adjusting the pH value of the mixed solution to 9.0 with a 10% potassium hydroxide solution, and reacting at 60° C. for 60 min to obtain a reaction product; S2, after adjusting the pH value of the reaction product to 6 with hydrochloric acid, 12g of cationic surfactant (dodecyltrimethylammonium chloride) was added and the reaction was continued for 30min to obtain a high-efficiency multifunctional clay stabilizer.

[0029] Embodiment 13: The high-efficiency multifunctional clay stabilizer for tight oil and gas reservoirs is obtained according to the following method: S1, adding 30g of silane coupling agent (trimethyl[3-(trimethoxysilyl)propyl]ammonium chloride) and 25g of ethylene glycol to 250g of a 65% aqueous solution of hexamethylphosphoric triamide at a stirring rate of 150r / min, and mixing to obtain a mixed solution, adjusting the pH value of the mixed solution to 9.0 with a 10% potassium hydroxide solution, and reacting at 60°C for 60min to obtain a reaction product; S2, after adjusting the pH value of the reaction product to 5.5 with hydrochloric acid, 10 g of cationic surfactant (hexadecyl trimethylacetoxy ammonium chloride) was added and the reaction was continued for 30 min to obtain a high-efficiency multifunctional clay stabilizer.

[0030] Embodiment 14: The high-efficiency multifunctional clay stabilizer for tight oil and gas reservoirs is obtained according to the following method: S1, adding 25 g of a silane coupling agent (trimethyl [3-(trimethoxysilyl)propyl] ammonium chloride) and 30 g of ethylene glycol to 250 g of a 65% aqueous solution of hexamethylphosphoric triamide at a stirring rate of 150 r / min, and mixing to obtain a mixed solution, adjusting the pH value of the mixed solution to 8.5 with a 10% potassium hydroxide solution, and reacting at 55° C. for 55 min to obtain a reaction product; S2, after adjusting the pH value of the reaction product to 5.5 with hydrochloric acid, 15 g of cationic surfactant (octadecyltrimethylammonium chloride) was added and the reaction was continued for 30 min to obtain a high-efficiency multifunctional clay stabilizer.

[0031] Comparative Example 1: The difference from Example 13 of the present invention is that the raw material silane coupling agent (trimethyl[3-(trimethoxysilyl)propyl]ammonium chloride) is replaced by methacryloyloxyethyltrimethylammonium chloride, and the remaining steps are the same as Example 13 of the present invention.

[0032] Example 15: The high-efficiency multifunctional clay stabilizers obtained in Examples 12 to 14 of the present invention were mixed with water to obtain high-efficiency multifunctional clay stabilizers A, B, C and D with a mass concentration of 0.5%. At the same time, the comparative example was used as a control, and the performance of clay stabilizers A, B, C and D was investigated according to the method specified in SY / T 5971-2016 "Performance Evaluation Method of Clay Stabilizers for Oil and Gas Field Fracturing Acidification and Water Injection", and their anti-swelling rate and water washing resistance were investigated. The test results are shown in Table 1. It can be seen from Table 1 that compared with the comparative example, the high-efficiency multifunctional clay stabilizers obtained in Examples 12 to 14 of the present invention have high anti-swelling rate and high water washing resistance, indicating that the high-efficiency multifunctional clay stabilizer of the present invention has a high anti-swelling effect and long-lasting performance.

[0033] Example 16: The core damage rate test was conducted on the high-efficiency multifunctional clay stabilizer obtained in Examples 12 to 14 of the present invention, wherein the core was taken from the Su 19 block of Changqing Oilfield. The specific operation is: saturating the core with standard brine, forward displacing the standard brine, and measuring the initial permeability K0 of the core, reversely injecting the clay stabilizer solution to damage the core, and after the flow rate and pressure are stable, measuring the final permeability K0 of the damaged core W , the calculation formula of core damage rate is: .

[0034] The core damage rate test results of the high-efficiency multifunctional clay stabilizer obtained in Examples 12 to 14 of the present invention are 9% to 14%, indicating that the high-efficiency multifunctional clay stabilizer of the present invention has a low core damage rate and can be used in tight oil and gas reservoirs.

[0035] Example 17: The surface tension, interfacial tension and contact angle tests were performed on the high-efficiency multifunctional clay stabilizers obtained in Examples 12 to 14 of the present invention. At the same time, Comparative Example 1 was used as a control. The test results are shown in Table 2. Compared with the comparative example, the surface tension and interfacial tension of the high-efficiency multifunctional clay stabilizers obtained in Examples 12 to 14 of the present invention are lower, indicating that the high-efficiency multifunctional clay stabilizer of the present invention has lower surface tension and interfacial tension, can improve the wettability of the clay surface, and achieve neutral / weak hydrophilicity (70°<contact angle<90°), which is conducive to the backflow of the working fluid and the imbibition / displacement effect.

[0036] In summary, the high-efficiency multifunctional clay stabilizer of the present invention not only has lower surface tension and interfacial tension, can improve the wettability of the clay surface, achieve neutral / weak hydrophilicity, has the effects of assisting drainage, imbibition / displacement, but also has higher anti-swelling effect and long-term effectiveness, and is suitable for tight oil and gas reservoirs.

[0037] The above technical features constitute the embodiments of the present invention, which have strong adaptability and implementation effect. Non-essential technical features can be added or reduced according to actual needs to meet the requirements of different situations.

Claims

1. A high-efficiency multifunctional clay stabilizer for tight oil and gas reservoirs, characterized in that Obtained as follows: S1, adding 25 to 30 parts of a silane coupling agent and 25 to 30 parts of ethylene glycol to 200 to 300 parts of an aqueous solution of hexamethylphosphoric triamide by mass under stirring, mixing to obtain a mixed solution, adjusting the pH of the mixed solution, and reacting to obtain a reaction product; S2, after adjusting the pH of the reaction product, 10 to 15 parts of a cationic surfactant are added to continue the reaction to obtain a high-efficiency multifunctional clay stabilizer.

2. The high-efficiency multifunctional clay stabilizer for tight oil and gas reservoirs according to claim 1, characterized in that The cationic surfactant is one or more of dodecyltrimethylammonium chloride, hexadecyltrimethylammonium chloride, hexadecyltrimethylammonium bromide, octadecyltrimethylammonium chloride, octadecyltrimethylammonium bromide, hexadecyltrimethylacetoxyammonium chloride, hexadecyltrimethylphenylammonium bromide and hexadecyltrimethylhydroxyethylammonium chloride.

3. The high-efficiency multifunctional clay stabilizer for tight oil and gas reservoirs according to claim 1 or 2, characterized in that The silane coupling agent is one or more of trimethyl[3-(trimethoxysilyl)propyl]ammonium chloride, aminosilane, butadienyltriethoxysilane and isobutyltriethoxysilane.

4. The high-efficiency multifunctional clay stabilizer for tight oil and gas reservoirs according to any one of claims 1 to 3, characterized in that In step S1, the mass concentration of the hexamethylphosphoric triamide aqueous solution is 55% to 65%.

5. The high-efficiency multifunctional clay stabilizer for tight oil and gas reservoirs according to any one of claims 1 to 4, characterized in that In step S1, during stirring, the stirring rate is 120 r / min to 150 r / min, the reaction temperature is 50° C. to 60° C., and the reaction time is 55 min to 60 min.

6. The high-efficiency multifunctional clay stabilizer for tight oil and gas reservoirs according to any one of claims 1 to 5, characterized in that In step S1, a potassium hydroxide solution with a mass concentration of 10% is used to adjust the pH value of the mixed solution to 8.5 to 9.

0.

7. The high-efficiency multifunctional clay stabilizer for tight oil and gas reservoirs according to any one of claims 1 to 6, characterized in that In step S2, the pH value of the reaction product is adjusted to 5 to 6 with hydrochloric acid, and the reaction time is 30 min to 40 min.

8. A method for preparing a high-efficiency multifunctional clay stabilizer for tight oil and gas reservoirs according to any one of claims 2 to 7, characterized in that Proceed as follows: S1, adding 25 to 30 parts of a silane coupling agent and 25 to 30 parts of ethylene glycol to 200 to 300 parts of an aqueous solution of hexamethylphosphoric triamide by mass under stirring, mixing to obtain a mixed solution, adjusting the pH of the mixed solution, and reacting to obtain a reaction product; S2, after adjusting the pH of the reaction product, 10 to 15 parts of a cationic surfactant are added to continue the reaction to obtain a high-efficiency multifunctional clay stabilizer.

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