Low-temperature gel breaking activating agent for fracturing fluid and preparation method of low-temperature gel breaking activating agent

Abstract

The invention relates to a low-temperature gel breaking activator for fracturing fluid and a preparation method thereof, and belongs to the technical field of fracturing fluid gel breaking assistants, the low-temperature gel breaking activator comprises the following components by weight: 3-5 parts of 2-mercaptoethyl trimethyl ammonium chloride, 12-25 parts of nickel chloride, 3-6 parts of diethylenetriamine penta (methylene phosphonic acid) sodium, 1-2 parts of dodecyl dimethyl benzyl ammonium chloride, and the balance of water, totaling 100 parts. The low-temperature gel breaking activator for the fracturing fluid can improve the reaction rate of a gel breaker of the fracturing fluid at low temperature, so that gel breaking is accelerated, and the gel breaking time is shortened. The preparation method disclosed by the invention is simple, easy for large-scale production and high in applicability.

Description

Technical Field

[0001] The invention belongs to the technical field of fracturing fluid debonding aids, and relates to a low-temperature debonding activator for fracturing fluid and a preparation method thereof. The activator can significantly improve the debonding performance of the fracturing fluid under low temperature conditions, thereby increasing the production of oil and gas wells. Background Art

[0002] Fracturing fluid is one of the commonly used production-increasing measures in oilfield development. It injects high-pressure fluid into the formation to create cracks in the formation, thereby increasing the flow channels for oil and gas. However, after use, the fracturing fluid needs to be quickly debonded to reduce its viscosity to facilitate subsequent fluid discharge and oil and gas flow.

[0003] At present, the commonly used fracturing fluid breakers mainly include oxidants and enzymes. Oxidants such as ammonium persulfate and potassium persulfate can effectively break the gel at high temperatures, but the effect is poor at low temperatures; although enzyme breakers are suitable for low temperatures, they require a lower pH value and are easily inactivated at high temperatures, making it difficult to meet the needs of low-temperature oil and gas fields.

[0004] A Chinese patent document with publication number CN 110408375 A discloses a low-temperature guar gum fracturing fluid, in which water-soluble Ag that is stable under alkaline conditions is used. + Ionic complexes are low-temperature activators, but they are only applicable to temperatures ranging from 20 to 50°C and cannot meet lower temperature requirements.

[0005] A Chinese patent document with publication number CN 103484092 A discloses an ultra-low temperature guar gum fracturing fluid, in which cuprous chloride or stannous chloride is used as an activator. However, it can only achieve fracturing transformation conditions of 15-35° C. and cannot meet lower temperature requirements.

[0006] Therefore, it is of great significance to develop an efficient debonding activator suitable for low temperature conditions. Summary of the invention

[0007] The present invention aims to provide a low-temperature degelling activator for fracturing fluid and a preparation method thereof, which is suitable for a fracturing transformation environment of ≥5°C.

[0008] The technical solution adopted by the present invention to achieve its purpose is as follows:

[0009] A low-temperature gel-breaking activator for fracturing fluid comprises, by weight, 3-5 parts of 2-mercaptoethyltrimethylammonium chloride, 12-25 parts of nickel chloride, 3-6 parts of sodium diethylenetriaminepenta(methylenephosphonate), 1-2 parts of dodecyldimethylbenzylammonium chloride, and water to make up to 100 parts.

[0010] Preferably, the mass ratio of 2-mercaptoethyltrimethylammonium chloride to nickel chloride is 1:(4-5).

[0011] Preferably, a pH regulator is also included, and the pH regulator is one or any combination of citric acid, sodium citrate, acetic acid, sodium acetate, glycolic acid, sulfonic acid amine, and ammonia water.

[0012] Preferably, the use temperature range of the low-temperature degelling activator for the fracturing fluid is ≥5°C.

[0013] A method for preparing a low-temperature degelling activator for fracturing fluid comprises the following steps:

[0014] S1. Dissolve sodium diethylenetriamine penta (methylene phosphonate) and dodecyl dimethyl benzyl ammonium chloride in water according to their mass fractions to obtain a premixed solution;

[0015] S2. Add 2-mercaptoethyltrimethylammonium chloride and nickel chloride thereto, stir evenly, and obtain a low-temperature debonding activator for fracturing fluid.

[0016] Preferably, after obtaining the premix, a pH adjuster is first added to adjust the pH value of the premix to 7-8.

[0017] Preferably, in step S3, the stirring time is 10-20 min.

[0018] The beneficial effects of the present invention are:

[0019] The low-temperature debonding activator for fracturing fluid of the present invention can improve the reaction rate of the debonding agent of fracturing fluid at low temperature, thereby accelerating debonding and shortening debonding time. The preparation method of the present invention is simple, easy to mass produce and highly applicable.

[0020] In the present invention, nickel chloride is used as the main activator, which can reduce the activation energy of the gel breaking reaction, increase the reaction rate of peroxides such as ammonium persulfate at low temperatures, and enable the reaction to proceed at relatively low temperatures.

[0021] In the present invention, 2-mercaptoethyltrimethylammonium chloride is used as an auxiliary activator. On the one hand, 2-mercaptoethyltrimethylammonium chloride contains a thiol group and has good reducing property, which can promote the decomposition of persulfate ions and generate more free radicals, accelerate the decomposition of ammonium persulfate, and thus improve the debonding efficiency; on the other hand, the presence of its cationic group can help it to be better dispersed in the fracturing fluid in the aqueous solution, and help it to be adsorbed on the polymer colloid network, so as to more effectively bring the activated persulfate to the polymer chain. This interfacial activity can accelerate the degradation process of the colloid network and improve the debonding efficiency.

[0022] The role of sodium diethylenetriamine penta (methylene phosphonate) is to be used as a stabilizer for the activator.

[0023] Dodecyl dimethyl benzyl ammonium chloride as a dispersant can improve the dispersibility of sodium diethylene triamine penta (methylene phosphonate), making it more evenly dispersed and better stabilizing. DETAILED DESCRIPTION

[0024] The present invention is described in detail below in conjunction with specific embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should belong to the scope of protection of the present invention. 1. Specific embodiments

[0026] Example 1

[0027] A low-temperature gel-breaking activator for a fracturing fluid comprises, by weight, 4 parts of 2-mercaptoethyltrimethylammonium chloride, 16 parts of nickel chloride, 4 parts of sodium diethylenetriaminepenta(methylenephosphonate), 2 parts of dodecyldimethylbenzylammonium chloride, water is added to 100 parts, and a pH regulator is used to adjust the pH value to 7.

[0028] A method for preparing a low-temperature degelling activator for fracturing fluid comprises the following steps:

[0029] S1. Dissolve sodium diethylenetriamine penta (methylene phosphonate) and dodecyl dimethyl benzyl ammonium chloride in water according to their mass fractions to obtain a premixed solution;

[0030] S2. Add a pH adjuster to the premixed liquid to adjust the pH value of the premixed liquid to 7; add 2-mercaptoethyltrimethylammonium chloride and nickel chloride thereto, stir evenly for 15 minutes, and obtain a low-temperature degelling activator for fracturing fluid.

[0031] Example 2

[0032] A low-temperature gel-breaking activator for a fracturing fluid comprises, by weight, 3 parts of 2-mercaptoethyltrimethylammonium chloride, 15 parts of nickel chloride, 3 parts of sodium diethylenetriaminepenta(methylenephosphonate), 1 part of dodecyldimethylbenzylammonium chloride, water is added to 100 parts, and a pH regulator is used to adjust the pH value to 8.

[0033] A method for preparing a low-temperature degelling activator for fracturing fluid comprises the following steps:

[0034] S1. Dissolve sodium diethylenetriamine penta (methylene phosphonate) and dodecyl dimethyl benzyl ammonium chloride in water according to their mass fractions to obtain a premixed solution;

[0035] S2. Add a pH adjuster to the premixed liquid to adjust the pH value of the premixed liquid to 8; add 2-mercaptoethyltrimethylammonium chloride and nickel chloride thereto, stir evenly for 10 minutes, and obtain a low-temperature degelling activator for fracturing fluid.

[0036] Example 3

[0037] A low-temperature gel-breaking activator for a fracturing fluid comprises, by weight, 5 parts of 2-mercaptoethyltrimethylammonium chloride, 20 parts of nickel chloride, 5 parts of sodium diethylenetriaminepenta(methylenephosphonate), 2 parts of dodecyldimethylbenzylammonium chloride, water is added to 100 parts, and a pH regulator is used to adjust the pH value to 7.5.

[0038] A method for preparing a low-temperature degelling activator for fracturing fluid comprises the following steps:

[0039] S1. Dissolve sodium diethylenetriamine penta (methylene phosphonate) and dodecyl dimethyl benzyl ammonium chloride in water according to their mass fractions to obtain a premixed solution;

[0040] S2. Add a pH adjuster to the premixed liquid to adjust the pH value of the premixed liquid to 7.5; add 2-mercaptoethyltrimethylammonium chloride and nickel chloride thereto, stir evenly for 20 minutes, and obtain a low-temperature degelling activator for fracturing fluid.

[0041] Example 4

[0042] A low-temperature gel-breaking activator for a fracturing fluid comprises, by weight, 3.5 parts of 2-mercaptoethyltrimethylammonium chloride, 21 parts of nickel chloride, 3.5 parts of sodium diethylenetriamine penta(methylenephosphonate), 1.5 parts of dodecyldimethylbenzylammonium chloride, water is added to 100 parts, and a pH regulator is used to adjust the pH value to 7.5.

[0043] A method for preparing a low-temperature degelling activator for fracturing fluid comprises the following steps:

[0044] S1. Dissolve sodium diethylenetriamine penta (methylene phosphonate) and dodecyl dimethyl benzyl ammonium chloride in water according to their mass fractions to obtain a premixed solution;

[0045] S2. Add a pH adjuster to the premixed liquid to adjust the pH value of the premixed liquid to 7.5; add 2-mercaptoethyltrimethylammonium chloride and nickel chloride thereto, stir evenly for 15 minutes, and obtain a low-temperature degelling activator for fracturing fluid.

[0046] Example 5

[0047] A low-temperature gel-breaking activator for a fracturing fluid comprises, by weight, 5 parts of 2-mercaptoethyltrimethylammonium chloride, 12.5 parts of nickel chloride, 4.5 parts of sodium diethylenetriamine penta(methylenephosphonate), 2 parts of dodecyldimethylbenzylammonium chloride, water supplemented to 100 parts, and a pH regulator adjusted to a pH value of 7.5.

[0048] A method for preparing a low-temperature degelling activator for fracturing fluid comprises the following steps:

[0049] S1. Dissolve sodium diethylenetriamine penta (methylene phosphonate) and dodecyl dimethyl benzyl ammonium chloride in water according to their mass fractions to obtain a premixed solution;

[0050] S2. Add a pH adjuster to the premixed liquid to adjust the pH value of the premixed liquid to 7.5; add 2-mercaptoethyltrimethylammonium chloride and nickel chloride thereto, stir evenly for 15 minutes, and obtain a low-temperature degelling activator for fracturing fluid.

[0051] Comparative Example 1

[0052] A low-temperature gel-breaking activator for a fracturing fluid comprises, by weight, 20 parts of nickel chloride, 4 parts of sodium diethylenetriamine penta (methylene phosphonate), 2 parts of dodecyl dimethyl benzyl ammonium chloride, water is added to 100 parts, and a pH regulator is used to adjust the pH value to 7.

[0053] A method for preparing a low-temperature degelling activator for fracturing fluid comprises the following steps:

[0054] S1. Dissolve sodium diethylenetriamine penta (methylene phosphonate) and dodecyl dimethyl benzyl ammonium chloride in water according to their mass fractions to obtain a premixed solution;

[0055] S2. Add a pH adjuster to the premixed liquid to adjust the pH value of the premixed liquid to 7; add 2-mercaptoethyltrimethylammonium chloride and nickel chloride thereto, stir evenly for 15 minutes, and obtain a low-temperature degelling activator for fracturing fluid.

[0056] 2. Performance Test

[0057] Prepare the guar fracturing fluid system: 0.2 parts of hydroxypropyl guar, 0.3 parts of organic boron crosslinking agent, 1.0 parts of clay stabilizer, 1.0 parts of drainage aid, 0.04 parts of ammonium persulfate, 0.01 parts of low-temperature debonding activator and 100 parts of water.

[0058] The prepared fracturing fluids were placed in constant temperature devices at 5°C, 10°C, 15°C, 30°C and 50°C, respectively, and left to stand to observe gel breaking. The results are shown in Tables 1 to 5.

[0059] Table 1

[0060]

[0061] Table 2

[0062]

[0063]

[0064] Table 3

[0065]

[0066] Table 4

[0067]

[0068] Table 5

[0069]

[0070] It can be seen from Tables 1 to 5 that the addition of the low-temperature debonding activator of the present invention can enable the fracturing fluid system to be constructed in a low-temperature environment, with excellent debonding effect, rapid debonding, and shortened debonding time.

Claims

1. A low-temperature degelling activator for fracturing fluid, characterized in that: By weight, it comprises 3-5 parts of 2-mercaptoethyltrimethylammonium chloride, 12-25 parts of nickel chloride, 3-6 parts of sodium diethylenetriaminepenta(methylenephosphonate), 1-2 parts of dodecyldimethylbenzylammonium chloride, and water is added to 100 parts.

2. A low-temperature degelling activator for fracturing fluid according to claim 1, characterized in that: The mass ratio of 2-mercaptoethyltrimethylammonium chloride to nickel chloride is 1:(4-5).

3. The low-temperature degelling activator for fracturing fluid according to claim 1, characterized in that: It also includes a pH adjuster, which is one or any combination of citric acid, sodium citrate, acetic acid, sodium acetate, glycolic acid, sulfonic acid amine, and ammonia water.

4. The low-temperature degelling activator for fracturing fluid according to claim 1, characterized in that: The use temperature range of the low-temperature degelling activator for the fracturing fluid is ≥5°C.

5. A method for preparing a low-temperature degelling activator for fracturing fluid, characterized in that: The following steps are involved: S1. Dissolve sodium diethylenetriamine penta (methylene phosphonate) and dodecyl dimethyl benzyl ammonium chloride in water according to their mass fractions to obtain a premixed solution; S2. Add 2-mercaptoethyltrimethylammonium chloride and nickel chloride thereto, stir evenly, and obtain a low-temperature debonding activator for fracturing fluid.

6. The method for preparing a low-temperature degelling activator for fracturing fluid according to claim 5, characterized in that: After obtaining the premixed solution, first add a pH adjuster to adjust the pH value of the premixed solution to 7-8.

7. The method for preparing a low-temperature degelling activator for fracturing fluid according to claim 5, characterized in that: In step S2, the stirring time is 10-20 min.

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