Temperature-resistant and acid-resistant delayed fracturing fluid cross-linking agent and preparation method thereof

Abstract

The invention belongs to the technical field of tertiary oil recovery, and particularly relates to a temperature-resistant and acid-resistant delayed fracturing fluid cross-linking agent and a preparation method thereof. The synthesis method comprises the following steps: adding N, N-bis (2-ethoxyl) aminomethylene diethyl phosphonate into a reactor, then adding zirconium oxychloride, reacting at normal temperature, slowly heating to 50-60 DEG C, and continuously carrying out heat preservation reaction; adding serine and a solvent into the reactor, slowly heating to 55-65 DEG C, carrying out heat preservation reaction, and cooling to 30 DEG C or below; and adding 10wt% of ammonia water to adjust the pH value to 6-7, and filtering to obtain yellow transparent liquid, namely the product cross-linking agent. The cross-linking agent has the advantages of being wide in raw material source, free of pollution, environmentally friendly, good in acid resistance, high in temperature resistance and shear resistance and adjustable in cross-linking time.

Description

Technical Field

[0001] The invention belongs to the technical field of tertiary oil recovery, and in particular relates to a heat-resistant and acid-resistant delayed-type fracturing fluid cross-linking agent and a preparation method thereof. Background Art

[0002] As oilfield exploitation enters the middle and late stages, the difficulty of exploitation is increasing. Unconventional oil and gas reservoir exploitation is an important direction for increasing production, and these oil and gas reservoirs are usually characterized by deep burial, low permeability, and high temperature. Fracturing transformation of such oil and gas reservoirs is an effective measure to increase production and the main means of reservoir transformation. Currently, there are fracturing processes such as water-based fracturing fluid, oil-based fracturing fluid, and foam fracturing fluid, among which water-based fracturing fluid is the most widely used. As oilfield exploration develops deeper, deep low-permeability reservoir fracturing technology plays an increasingly important role.

[0003] The performance of fracturing fluid is a key factor in the effect of fracturing and reforming rock formations. Fracturing fluid is a non-Newtonian fluid, which is required to have high temperature resistance, salt resistance, shear resistance, sand carrying, drag reduction and other properties. During the fracturing process, the fracturing fluid goes through cross-linking, temperature change, variable shear flow and gel breaking and return process from the ground to the reservoir, which is a typical reaction rheological dynamics process and is closely related to the transfer and reaction process of non-Newtonian fluids. In fracturing construction, the cross-linking reaction and rheological process of the fracturing fluid affect each other. The rheological properties of the fracturing fluid directly affect the effect of the fracturing construction process. The fracturing fluid is the key factor in determining the success or failure of the fracturing construction.

[0004] The quality of the cross-linking agent is crucial to the construction effect of the fracturing fluid. There are many types of cross-linking agents. Organic boron cross-linking agent is the main cross-linking agent for plant gum water-based fracturing fluids. These plant gums mainly include guar gum, konjac gum, sesbania gum, etc., but the cross-linking effect on polyacrylamide is not ideal; organic aluminum cross-linking agent is stable at low pH values, but it is easy to hydrolyze at high temperature and high mineralization, and the gel is unstable, so the scope of use is greatly limited; organic zirconium has good cross-linking ability, zirconium compounds have a strong affinity for hydroxyl groups, and have the advantages of a stable positive tetravalent oxidation state and low toxicity, so it is more widely applicable. The bond formed between the zirconium compound and the polymer reaction group has good thermal stability, and the gel formed can be used in high-temperature deep wells. For the high temperature and low pH environment of the reservoir, zirconium cross-linked fracturing fluid can ensure the normal fracturing acidification, so the realization of acid cross-linking is of great significance in oil field development and production increase.

[0005] CN106800927A discloses a guar fracturing fluid crosslinker, comprising a first component and a second component, wherein the first component comprises a polyhydroxy compound, boric acid and an organic amine, and the second component comprises an inorganic base, a metal ion complexing agent and water; the weight ratio of the first component to the second component is 0.25-2.5:1. The invention provides a method for preparing the crosslinker, comprising: preparing the first component: adding the polyhydroxy compound to the first reactor at room temperature, adding boric acid under stirring, heating to 43-53°C, keeping the temperature constant for 25-35 minutes, adding an organic amine to the first reactor, controlling the reaction temperature to 55-65°C, keeping the temperature constant for 25-35 minutes, and cooling to room temperature to obtain the first component; preparing the second component: adding water to the second reactor, adding the metal ion complexing agent under stirring until it is completely dissolved, adding the inorganic base to the second reactor in batches, controlling the reaction temperature to be lower than 70°C, stirring the reaction until the solution is clear, and cooling to room temperature to obtain the second component. The invention also provides a guar fracturing fluid using the crosslinker. The cross-linking agent of the invention can only act on plant gums, especially hydroxypropyl guar gum, and cannot achieve effective cross-linking of polyacrylamide under acidic conditions.

[0006] CN104560003A discloses an organic boron zirconium crosslinking agent, which belongs to the technical field of oilfield fracturing fluid. In order to solve the problems that the existing organic boron zirconium crosslinking agent is prepared with expensive organic zirconium complex as raw material, which reduces its economic benefits, the invention provides an organic boron zirconium crosslinking agent, the formula of which is (by weight): 1 part of inorganic zirconium salt; 2-4 parts of water; 3-6 parts of isopropanol; 0.4-1 part of inorganic boron compound; 4-20 parts of methanol; 2-4 parts of polyol; 1-2 parts of sodium α-hydroxycarboxylate; 1-2 parts of triethanolamine; 0.5-1 part of tetrahydroxypropyl ethylenediamine. The organic boron zirconium crosslinking agent provided by the invention uses cheap inorganic zirconium salt as raw material, which greatly saves costs and is conducive to the marketization of organic boron zirconium crosslinking agents and their wide application in high temperature resistant fracturing fluid systems. According to the viscosity-temperature curve provided, the viscosity of the crosslinking agent fracturing fluid of the invention is less than 100mPa·s after 80 minutes of shearing, and the shear resistance needs to be further improved. Summary of the invention

[0007] The present invention aims to provide a heat-resistant and acid-resistant delayed fracturing fluid crosslinking agent and a synthesis method thereof in view of the above-mentioned deficiencies in the prior art. The crosslinking agent has the advantages of wide raw material sources, no pollution, environmental friendliness, good acid resistance, strong heat and shear resistance, and adjustable crosslinking time.

[0008] One of the purposes of the present invention is to disclose a heat-resistant and acid-resistant delayed-action fracturing fluid crosslinking agent, the molecular structure of which is as follows:

[0009]

[0010] Another object of the present invention is to disclose a method for synthesizing a heat-resistant and acid-resistant delayed-type fracturing fluid cross-linking agent, the specific steps of which are as follows:

[0011] (1) Add N,N-bis(2-hydroxyethyl)aminomethylenephosphonic acid diethyl ester to a reactor, then add zirconium oxychloride, react at room temperature, slowly heat to 50-60° C., and continue to keep the temperature for reaction;

[0012] (2) Add serine and solvent to the above reactor, slowly heat to 55-65° C., keep warm for reaction, and cool to below 30° C.;

[0013] (3) Add 10 wt % ammonia water to adjust the pH to 6-7, filter, and obtain a yellow transparent liquid, i.e., the product cross-linking agent.

[0014] In the present invention, preferably, the molar ratio of N,N-bis(2-hydroxyethyl)aminomethylenephosphonic acid diethyl ester, serine and zirconium oxychloride is 1.5-3:1.5-2.5:1; more preferably, the molar ratio of N,N-bis(2-hydroxyethyl)aminomethylenephosphonic acid diethyl ester, serine and zirconium oxychloride is 2-2.5:1.5-2.0:1.

[0015] In the present invention, preferably, the room temperature reaction time in step (1) is 0.5-1h.

[0016] Preferably, the insulation reaction time in step (1) is 1-2 h; more preferably, the insulation reaction time is 1.5-2 h.

[0017] In the present invention, preferably, the solvent described in step (2) is one of methanol, ethanol, propanol and ethylene glycol, and the weight ratio of the solvent to zirconium oxychloride is 3-5:1.

[0018] Preferably, the insulation reaction time in step (2) is 2-3 h; more preferably, the insulation reaction time is 2-2.5 h.

[0019] The reaction equation for synthesizing the heat-resistant and acid-resistant delayed-action fracturing fluid crosslinking agent of the present invention is as follows:

[0020]

[0021]

[0022] The present invention is an organic zirconium crosslinking agent, which can crosslink guar gum and polyacrylamide. N, N-bis (2-hydroxyethyl) aminomethylenephosphonic acid diethyl ester is the organic body of the crosslinking agent, which has a strong metal chelating ability, and the generated zirconium phosphate is very stable; serine is the ligand of the crosslinking agent, and amino nitrogen has a lone pair of electrons, which can coordinate around the zirconium atom to enhance the stability of the crosslinking agent; the present invention can adjust the crosslinking time by adjusting the number of the organic body and the ligand. The present invention contains a large number of hydroxyl groups and carboxyl groups, and can form multi-nuclear hydroxyl bridges and multi-nuclear carboxyl bridges, thereby enhancing the viscosity and strength of the crosslinked fracturing fluid.

[0023] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0024] (1) The cross-linking agent of the present invention has a wide range of raw material sources, a simple synthesis process, strong adaptability, and a small amount of use;

[0025] (2) The crosslinking agent of the present invention has strong acid resistance, and the pH is less than 2;

[0026] (3) The cross-linking agent of the present invention has strong heat and shear resistance, and the viscosity reaches more than 300 mPa·s;

[0027] (4) The crosslinking time of the crosslinking agent of the present invention can be controlled in a wide range, which can be controlled between 80-900s. DETAILED DESCRIPTION

[0028] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0029] The present invention will be further described below with reference to specific embodiments.

[0030] In the present invention, the devices or equipment used are all conventional devices or equipment known in the art and are commercially available.

[0031] In the following examples and comparative examples, unless otherwise specified, all reagents used were commercially available chemically pure reagents.

[0032] Example 1

[0033] (1) Add 0.3 mol of N,N-bis(2-hydroxyethyl)aminomethylenephosphonic acid diethyl ester and 0.2 mol of zirconium oxychloride into a reactor, react at room temperature for 0.5 h, slowly heat to 50° C., and continue to react at this temperature for 1 h;

[0034] (2) Add 0.3 mol of serine and 147 g of ethanol to the above reactor, slowly heat to 55° C., keep the temperature for 2 h, and then cool to below 30° C.;

[0035] (3) Add 10 wt % ammonia water to adjust the pH to 6-7, filter, and obtain a yellow transparent liquid, i.e., the cross-linking agent product N1.

[0036] Example 2

[0037] (1) Add 0.3 mol of N,N-bis(2-hydroxyethyl)aminomethylenephosphonic acid diethyl ester and 0.2 mol of zirconium oxychloride into a reactor, react at room temperature for 1 hour, slowly heat to 60°C, and continue to keep the temperature for 2 hours;

[0038] (2) Add 0.4 mol of serine and 108 g of ethanol to the above reactor, slowly heat to 65° C., keep the temperature for 3 h, and then cool to below 30° C.;

[0039] (3) Add 10 wt % ammonia water to adjust the pH to 6-7, filter, and obtain a yellow transparent liquid, i.e., the cross-linking agent product N2.

[0040] Example 3

[0041] (1) Add 0.35 mol of N,N-bis(2-hydroxyethyl)aminomethylenephosphonic acid diethyl ester and 0.2 mol of zirconium oxychloride into a reactor, react at room temperature for 0.5 h, slowly heat to 55° C., and continue to react at this temperature for 1 h;

[0042] (2) Add 0.3 mol of serine and 120 g of methanol to the above reactor, slowly heat to 58° C., keep the temperature for 2.5 hours, and then cool to below 30° C.;

[0043] (3) Add 10 wt % ammonia water to adjust the pH to 6-7, filter, and obtain a yellow transparent liquid, i.e., the cross-linking agent product N3.

[0044] Example 4

[0045] (1) Add 0.35 mol of N,N-bis(2-hydroxyethyl)aminomethylenephosphonic acid diethyl ester and 0.2 mol of zirconium oxychloride into a reactor, react at room temperature for 1 hour, slowly heat to 52°C, and continue to keep the temperature for 2 hours;

[0046] (2) Add 0.35 mol of serine and 178 g of ethanol to the above reactor, slowly heat to 60° C., keep the temperature for 2 h, and then cool to below 30° C.;

[0047] (3) Add 10 wt % ammonia water to adjust the pH to 6-7, filter, and obtain a yellow transparent liquid, i.e., the cross-linking agent product N4.

[0048] Example 5

[0049] (1) Add 0.4 mol of N,N-bis(2-hydroxyethyl)aminomethylenephosphonic acid diethyl ester and 0.2 mol of zirconium oxychloride into a reactor, react at room temperature for 0.5 h, slowly heat to 58° C., and continue to keep the temperature for 1.5 h;

[0050] (2) Add 0.35 mol of serine and 142 g of propanol to the above reactor, slowly heat to 57° C., keep the temperature for 2 h, and then cool to below 30° C.;

[0051] (3) Add 10 wt% ammonia water to adjust the pH to 6-7, filter, and obtain a yellow transparent liquid, i.e., the cross-linking agent product N5.

[0052] Example 6

[0053] (1) Add 0.4 mol of N,N-bis(2-hydroxyethyl)aminomethylenephosphonic acid diethyl ester and 0.2 mol of zirconium oxychloride into a reactor, react at room temperature for 1 hour, slowly heat to 57°C, and continue to keep the temperature for 1.5 hours;

[0054] (2) Add 0.4 mol of serine and 145 g of ethanol to the above reactor, slowly heat to 62° C., keep the temperature for 2.5 hours, and then cool to below 30° C.;

[0055] (3) Add 10 wt % ammonia water to adjust the pH to 6-7, filter, and obtain a yellow transparent liquid, i.e., the cross-linking agent product N6.

[0056] Example 7

[0057] (1) Add 0.45 mol of N,N-bis(2-hydroxyethyl)aminomethylenephosphonic acid diethyl ester and 0.2 mol of zirconium oxychloride into a reactor, react at room temperature for 0.5 h, slowly heat to 53° C., and continue to keep the temperature for 1.5 h;

[0058] (2) Add 0.35 mol of serine and 152 g of ethylene glycol to the above reactor, slowly heat to 65° C., keep the temperature for 2.5 h, and then cool to below 30° C.;

[0059] (3) Add 10 wt % ammonia water to adjust the pH to 6-7, filter, and obtain a yellow transparent liquid, i.e., the cross-linking agent product N7.

[0060] Example 8

[0061] (1) Add 0.45 mol of N,N-bis(2-hydroxyethyl)aminomethylenephosphonic acid diethyl ester and 0.2 mol of zirconium oxychloride into a reactor, react at room temperature for 1 hour, slowly heat to 57°C, and continue to keep the temperature for 1.5 hours;

[0062] (2) Add 0.5 mol of serine and 158 g of methanol to the above reactor, slowly heat to 55° C., keep the temperature for 3 h, and then cool to below 30° C.;

[0063] (3) Add 10 wt % ammonia water to adjust the pH to 6-7, filter, and obtain a yellow transparent liquid, i.e., the cross-linking agent product N8.

[0064] Example 9

[0065] (1) Add 0.5 mol of N,N-bis(2-hydroxyethyl)aminomethylenephosphonic acid diethyl ester and 0.2 mol of zirconium oxychloride into a reactor, react at room temperature for 0.75 h, slowly heat to 59° C., and continue to keep the temperature for 1.5 h;

[0066] (2) Add 0.4 mol of serine and 150 g of propanol to the above reactor, slowly heat to 65° C., keep the temperature for 3 h, and then cool to below 30° C.;

[0067] (3) Add 10 wt % ammonia water to adjust the pH to 6-7, filter, and obtain a yellow transparent liquid, i.e., the cross-linking agent product N9.

[0068] Example 10

[0069] (1) Add 0.5 mol of N,N-bis(2-hydroxyethyl)aminomethylenephosphonic acid diethyl ester and 0.2 mol of zirconium oxychloride into a reactor, react at room temperature for 0.75 h, slowly heat to 52° C., and continue to react at this temperature for 2 h;

[0070] (2) Add 0.45 mol of serine and 150 g of ethanol to the above reactor, slowly heat to 60° C., keep the temperature for 3 h, and then cool to below 30° C.;

[0071] (3) Add 10 wt% ammonia water to adjust the pH to 6-7, filter, and obtain a yellow transparent liquid, i.e., the crosslinking agent product N 10 .

[0072] Embodiment 11

[0073] (1) Add 0.55 mol of N,N-bis(2-hydroxyethyl)aminomethylenephosphonic acid diethyl ester and 0.2 mol of zirconium oxychloride into a reactor, react at room temperature for 1 hour, slowly heat to 55°C, and continue to keep the temperature for 2 hours;

[0074] (2) Add 0.4 mol of serine and 170 g of ethanol to the above reactor, slowly heat to 55° C., keep the temperature for 3 h, and then cool to below 30° C.;

[0075] (3) Add 10 wt% ammonia water to adjust the pH to 6-7, filter, and obtain a yellow transparent liquid, i.e., the crosslinking agent product N11 .

[0076] Example 12

[0077] (1) Add 0.55 mol of N,N-bis(2-hydroxyethyl)aminomethylenephosphonic acid diethyl ester and 0.2 mol of zirconium oxychloride into a reactor, react at room temperature for 1 hour, slowly heat to 50°C, and continue to react at this temperature for 2 hours.

[0078] (2) Add 0.4 mol of serine and 155 g of ethanol to the above reactor, slowly heat to 65° C., keep the temperature for 3 h, and then cool to below 30° C.;

[0079] (3) Add 10 wt% ammonia water to adjust the pH to 6-7, filter, and obtain a yellow transparent liquid, i.e., the crosslinking agent product N 12 .

[0080] Example 13

[0081] (1) Add 0.6 mol of N,N-bis(2-hydroxyethyl)aminomethylenephosphonic acid diethyl ester and 0.2 mol of zirconium oxychloride into a reactor, react at room temperature for 1 hour, slowly heat to 60°C, and continue to react at this temperature for 2 hours.

[0082] (2) Add 0.5 mol of serine and 165 g of ethanol to the above reactor, slowly heat to 55° C., keep the temperature for 3 h, and then cool to below 30° C.;

[0083] (3) Add 10 wt% ammonia water to adjust the pH to 6-7, filter, and obtain a yellow transparent liquid, i.e., the crosslinking agent product N 13 .

[0084] Embodiment 14

[0085] (1) Add 0.6 mol of N,N-bis(2-hydroxyethyl)aminomethylenephosphonic acid diethyl ester and 0.2 mol of zirconium oxychloride into a reactor, react at room temperature for 1 hour, slowly heat to 55°C, and continue to react at this temperature for 2 hours.

[0086] (2) Add 0.5 mol of serine and 180 g of ethanol to the above reactor, slowly heat to 60° C., keep the temperature for 2.5 hours, and then cool to below 30° C.;

[0087] (3) Add 10 wt% ammonia water to adjust the pH to 6-7, filter, and obtain a yellow transparent liquid, i.e., the crosslinking agent product N 14 .

[0088] Test Example 1 Acid resistance test

[0089] Dissolve 5g of polyacrylamide in 1000ml of tap water, add 5g of cross-linking agent, stir evenly to obtain fracturing fluid, add the above fracturing fluid into the sample cup of Fann-35 rotary viscometer, heat the sample while stirring, control the heating rate to 3℃ / min, and the rotor to a shear rate of 170S. - After the temperature reaches 90°C, 10 wt% hydrochloric acid is added to the sample cup in portions. When the viscosity drops to 50 mPa·s, the corresponding pH is the acid resistance pH of the fracturing fluid. The test results are shown in Table 1.

[0090] From Table 1 we can see that:

[0091] The crosslinking agent N1-N of the present invention 14 The acid resistance pH value is less than 2, and the crosslinking agent N 14 The acid resistance pH value reaches 1; while the acid resistance value of the comparative cross-linking agent EXP-4901 is 3.8, and the acid resistance performance is significantly lower than that of the present invention.

[0092] Test Example 2 Evaluation of heat and shear resistance

[0093] Refer to 7.5 of Q / SH10202380-2020 "Technical Requirements for High-Temperature Cross-linking Agents for Fracturing Fluids" and the test results are shown in Table 1.

[0094] From Table 1 we can see that:

[0095] The crosslinking agent N1-N of the present invention 14 The temperature and shear resistance viscosity are all greater than 300mPa·s, among which the crosslinking agent N 14 The heat-resistant and shear-resistant viscosity reaches 360 mPa·s; while the heat-resistant and shear-resistant viscosity of the comparative cross-linking agent EXP-4901 is 106 mPa·s, and the heat-resistant and shear-resistant performance is significantly lower than that of the present invention.

[0096] Test Example 3 Cross-linking time test

[0097] Refer to 7.3 of Q / SH10202380-2020 "Technical Requirements for High-Temperature Cross-linking Agents for Fracturing Fluids" and the test results are shown in Table 1.

[0098] It can be seen from the table that the cross-linking time can be controlled between 80-900s, and the adjustable time range is very wide, so rock formations of different depths can be used for fracturing.

[0099] Table 1 Test results of acid resistance, heat resistance, shear resistance and cross-linking time

[0100]

[0101]

[0102] From Table 1 we can see that:

[0103] The crosslinking agent N1-N of the present invention 14 The cross-linking time ranges from 80 to 900 seconds, with the cross-linking time of cross-linker N1 being 80 seconds and that of cross-linker N 14 The cross-linking time was 900s; while the cross-linking time of the comparative cross-linker EXP-4901 was 130s.

[0104] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for synthesizing a heat-resistant and acid-resistant delayed-action fracturing fluid crosslinking agent, characterized in that: The specific steps of the synthetic method are as follows: (1) Add N,N-bis(2-hydroxyethyl)aminomethylenephosphonic acid diethyl ester to a reactor, then add zirconium oxychloride, react at room temperature, slowly heat to 50-60° C., and continue to keep the temperature for reaction; (2) Add serine and solvent to the above reactor, slowly heat to 55-65° C., keep warm for reaction, and cool to below 30° C.; (3) adding 10 wt % ammonia water to adjust the pH to 6-7, filtering, and obtaining a yellow transparent liquid, i.e., the product cross-linking agent; The molar ratio of N,N-bis(2-hydroxyethyl)aminomethylenephosphonic acid diethyl ester, serine and zirconium oxychloride is 1.5-3:1.5-2.5:

1. The molecular structural formula of the cross-linking agent is as follows:

2. The method for synthesizing a heat-resistant and acid-resistant delayed-action fracturing fluid crosslinking agent as claimed in claim 1, characterized in that: The molar ratio of N,N-bis(2-hydroxyethyl)aminomethylenephosphonic acid diethyl ester, serine and zirconium oxychloride is 2-2.5:1.5-2.0:

1.

3. The method for synthesizing a heat-resistant and acid-resistant delayed-action fracturing fluid crosslinking agent as claimed in claim 1, characterized in that: The reaction time at room temperature in step (1) is 0.5-1h.

4. The method for synthesizing a heat-resistant and acid-resistant delayed-action fracturing fluid crosslinking agent according to claim 1, characterized in that: The heat preservation reaction time described in step (1) is 1-2h.

5. The method for synthesizing a heat-resistant and acid-resistant delayed-action fracturing fluid crosslinking agent as claimed in claim 4, characterized in that: The insulation reaction time is 1.5-2h.

6. The method for synthesizing a heat-resistant and acid-resistant delayed-action fracturing fluid crosslinking agent according to claim 1, characterized in that: The solvent described in step (2) is one of methanol, ethanol, propanol and ethylene glycol, and the weight ratio of the solvent to zirconium oxychloride is 3-5:

1.

7. The method for synthesizing a heat-resistant and acid-resistant delayed-action fracturing fluid crosslinking agent as claimed in claim 1, characterized in that: The heat preservation reaction time described in step (2) is 2-3h.

8. The method for synthesizing a heat-resistant and acid-resistant delayed-action fracturing fluid crosslinking agent as claimed in claim 7, characterized in that: The insulation reaction time is 2-2.5h.

9. A heat-resistant and acid-resistant delayed-action fracturing fluid crosslinking agent, characterized in that: The molecular structural formula of the cross-linking agent is as follows:

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