Gel crosslinking agent, preparation method and application thereof
By designing gel crosslinking agents based on quaternary ammonium salts and rigid planar benzene derivatives, the problems of difficulty in breaking the gel and contamination of the reservoir by existing gel plugging agents in oilfield wellhead operations have been solved, realizing the application of high-temperature self-degrading gel plugging agents and improving operational efficiency and safety.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- YANGTZE UNIVERSITY
- Filing Date
- 2023-10-31
- Publication Date
- 2026-05-19
AI Technical Summary
Existing gel-based plugging agents present problems such as difficulty in breaking the gel, reservoir contamination, and high construction difficulty in oilfield wellhead operations, affecting operational efficiency and safety.
A gel crosslinking agent containing a quaternary ammonium salt structure and a rigid planar benzene derivative was designed. It can self-degrade under certain temperature conditions and form a three-dimensional network structure through chemical crosslinking. It is suitable for high-temperature degradable gel plugging agents and can be used for temporary plugging and maintenance of oilfield wells.
It achieves spontaneous degradation under high temperature conditions, avoiding the use of additional breaker agents. The degradation product has low viscosity and does not affect subsequent water injection, simplifying the wellhead operation process and reducing construction risks and costs.
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Figure CN117603066B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of oilfield chemistry and application, and relates to a gel crosslinking agent, its preparation method and its application. Background Technology
[0002] In oilfields employing water injection development, a large number of pressurized water injection wells require inspection and workover operations annually as development progresses, resulting in substantial operational demands. Conventional well control measures involve large overflows during tubing string setup and setup, posing significant well control risks and making flowback fluid treatment difficult. Currently, pressurized water injection well operations primarily employ two methods: conventional operations after depressurization and live operation, to ensure the smooth conduct of inspection and workover operations for high-pressure water injection wells. Because wellhead pressures in pressurized water injection wells in oilfields are generally high, with tubing pressures typically exceeding 10 MPa, depressurization involves a very large drainage volume and costly wastewater treatment, while the long blowout cycle also impacts operational efficiency. Live operation, with its complex tubing string setup and setup procedures, long average well dwell time, and high operational costs, further complicates the process.
[0003] Before gelation, polymer gel materials exhibit good rheological properties and are easy to inject; after gelation, they are deformable and have adjustable plugging strength. Therefore, polymer gels have unique advantages in plugging operations. Due to their high deformability, polymer gel materials are not limited by leakage channels. After injection, they can crosslink and copolymerize easily flowing polymer or monomer solutions to form non-flowing gels or jelly, which can produce a plugging effect in extremely small channels. This material is liquid before injection, and after injection, under formation conditions, it transforms into a solid gel with a three-dimensional network structure due to crosslinking, exhibiting excellent plugging properties. Chinese patent CN2017105939325 provides an o-nitrobenzene diacetal diacrylate, which is used as a crosslinking agent. The o-nitrobenzene diacetal diacrylate contains ether groups in its structure and requires light and acid conditions to degrade. However, existing domestic gel-based plugging agents are difficult to apply for temporary plugging operations due to problems such as difficulty in breaking down the gel and reservoir contamination, resulting in high difficulty and risk in on-site construction. Summary of the Invention
[0004] The purpose of this invention is to overcome the problems of existing gel-based plugging agents, such as difficulty in breaking down the gel, inability to spontaneously degrade, and reservoir contamination, and to provide a gel crosslinking agent, its preparation method, and its application.
[0005] To achieve the above objectives, the present invention provides the following technical solution:
[0006] The first objective of this invention is to provide a gel crosslinking agent, the general structural formula of which is shown in Formula I:
[0007]
[0008] in, n=1~3; X=F, Cl, Br or I;
[0009]
[0010] The gel crosslinking agent designed in this invention, whose structure includes a quaternary ammonium salt structure and a rigid planar benzene derivative, can self-degrade under certain temperature conditions without the need for an additional breaker. The quaternary ammonium salt structure can increase the hydrolysis rate of adjacent ester groups, thereby achieving the required self-degradation performance; the introduction of the rigid planar benzene derivative can improve the stability of the crosslinking agent itself.
[0011] Furthermore, in the structure of the gel crosslinking agent X = F, Cl, Br, or I;
[0012]
[0013] The dihalogenated compounds of the rigid planar benzene derivatives with the aforementioned R1 structure can form a more compact three-dimensional spatial structure during the crosslinking process.
[0014] The second objective of this invention is to provide a method for preparing a gel crosslinking agent:
[0015] The synthetic route of the gel crosslinking agent is as follows:
[0016]
[0017] in, n=1~3; X=F, Cl, Br or I;
[0018]
[0019] The preparation method of the gel crosslinking agent includes the following steps:
[0020] S1: Dissolve compound A in an organic solvent and stir thoroughly until homogeneous; then add an appropriate amount of polymerization inhibitor and compound B, and stir thoroughly at room temperature until homogeneous before use;
[0021] S2: Heat and stir, react for 12-48 hours, wash with ether, recrystallize with ethanol, filter and dry to obtain gel crosslinking agent.
[0022] Furthermore, the organic solvent is one or more of methanol or ethanol.
[0023] Furthermore, in the structure of the gel crosslinking agent X = F, Cl, Br, or I;
[0024]
[0025] Furthermore, the molar mass ratio of compound A to compound B is 4 to 2:1.
[0026] Furthermore, the heating temperature in step S2 is 40–65°C.
[0027] Furthermore, the polymerization inhibitor is a polyphenol or a phenothiazine, wherein the polyphenol is hydroquinone or catechol.
[0028] The method of the present invention can prepare gel crosslinking agents with good performance, and the technology is simple, reliable, and has a high yield, making it suitable for large-scale industrial production.
[0029] A third objective of this invention is to provide an application of a gel crosslinking agent in the formulation of a high-temperature degradable gel plugging agent for oilfield use.
[0030] The high-temperature biodegradable gel plugging agent is composed of the following raw materials:
[0031] Propylene monomers 10.0 wt% to 15 wt%
[0032] Gel crosslinking agent 1.0% wt%
[0033] Initiator 0.01wt%~0.001wt%
[0034] The remainder is water;
[0035] Furthermore, the propylene monomer is one or more of acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, acrylic acid, acrylonitrile, etc.
[0036] Furthermore, the general structural formula of the gel crosslinking agent is shown in Formula I:
[0037]
[0038] in, n=1~3; X=F, Cl, Br, I;
[0039]
[0040] Furthermore, the initiator is one or more of ammonium persulfate and azobisisobutyramidine hydrochloride.
[0041] Furthermore, the application temperature of the high-temperature biodegradable gel plugging agent is 90℃~120℃.
[0042] Furthermore, the gelation time of the high-temperature degradable gel plugging agent is 1.5 to 3 hours.
[0043] Furthermore, the high-temperature biodegradable gel plugging agent has a degradation time of 5–10 days, and its viscosity is less than 10 mPa·s after complete degradation.
[0044] Compared with the prior art, the beneficial effects of the present invention are:
[0045] The gel crosslinking agent designed in this invention can degrade spontaneously under certain temperature conditions without additional conditions such as light, acidic conditions or alkaline conditions.
[0046] The method of this invention can prepare gel crosslinking agents with good performance, and the technology is simple, reliable, and has a high yield, making it suitable for large-scale industrial production.
[0047] The application of the gel crosslinking agent of the present invention in high-temperature biodegradable gel plugging agent forms a three-dimensional network structure through chemical crosslinking. Under the action of the built-in catalyst, the weak bonds in the functional crosslinking agent break, the three-dimensional network structure disintegrates, and the generated linear low molecular weight water-soluble polymer dissolves in the formation water to form a low viscosity fluid. No backflow is required, and it does not affect subsequent water injection. It can realize temporary plugging and maintenance of oilfield wells. Attached Figure Description
[0048] Figure 1 This is the infrared spectrum of compound 1.
[0049] Figure 2 This is the 1H NMR spectrum of compound 1.
[0050] Figure 3 The infrared spectrum of control compound 1 is shown below.
[0051] Figure 4 The image shows the 1H NMR spectrum of the control compound 1. Detailed Implementation
[0052] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.
[0053] Example 1 (Synthesis of Compound 1)
[0054]
[0055] S1: Dissolve compound A1 (CAS No.: 2426-54-2) in methanol solution and stir thoroughly until homogeneous; then add the polymerization inhibitor phenothiazine and compound B1, and stir thoroughly at room temperature until homogeneous before use;
[0056] The molar ratio of compound A1 to compound B1 is 2:1;
[0057] S2: Under stirring conditions, the mixture was heated to 40°C and reacted for 12 hours. After washing with ether and recrystallization with ethanol, the mixture was filtered and dried to obtain gel crosslinking agent compound 1.
[0058] Characterization of compound 1 as follows Figure 1-2 As shown.
[0059] In compound 1 Figure 1 Middle, 3413cm -1 The characteristic absorption peak of NH is at 1587 cm⁻¹. -1 The peak at 1454 cm⁻¹ represents the stretching vibration of the C-H bond in the double bond. -1 and 1365cm -1 The absorption peaks at 1062 cm⁻¹ are the deformation vibration absorption peaks of the methylene and methyl groups, respectively. -1 The absorption peak at 989 cm⁻¹ is the C=O group of the ester group. -1 The vibration at this point is an out-of-plane deformation vibration of the benzene ring; 796 cm⁻¹ -1 The peak at this point represents the out-of-plane bending vibration of the =C—H double bond. Infrared spectroscopy reveals characteristic absorption peaks for the benzene ring, carbon-carbon double bond, and ester group in the crosslinking agent, indicating successful synthesis of the target crosslinking agent.
[0060] The proton NMR spectrum of compound 1 is shown below. Figure 2 As shown in the figure, position 7.27 represents the chemical shift of the proton on the benzene ring, positions 6.41 and 5.86 represent the chemical shifts of the carbon-carbon double bond, position 4.56 represents the chemical shift of the proton connecting the ester group, position 3.23 represents the chemical shift of the methylene hydrogen atom connecting the nitrogen atom, and position 1.34 represents the chemical shift of the methyl hydrogen atom connecting the nitrogen atom. The spectrum shows that the synthesized crosslinking agent contains both carbon-carbon double bonds and ester groups, and all protons in the molecular structure of the crosslinking agent appear in the spectrum, indicating that the synthesized crosslinking agent conforms to the expected designed structure.
[0061] Example 2 (Synthesis of Compound 2)
[0062]
[0063] The synthesis method of compound A1 in this embodiment is as follows: acrylic acid, 6-aminohexanol and diethylamine are added sequentially to a three-necked flask purged with N2. After reacting for 24 hours under heating and stirring conditions, the product is separated from the reaction mixture through extraction, washing and drying steps to obtain the compound. The synthesis method of A1 is existing technology.
[0064] S1: Dissolve compound A1 in an ethanol solution and stir thoroughly until homogeneous; then add the polymerization inhibitor hydroquinone and compound B2, and stir thoroughly at room temperature until homogeneous before use;
[0065] The molar ratio of compound A1 to compound B2 is 3:1;
[0066] S2: Under stirring conditions, the mixture was heated to 50°C and reacted for 24 hours. After washing with ether and recrystallization with ethanol, the mixture was filtered and dried to obtain gel crosslinking agent compound 2.
[0067] Example 3 (Synthesis of Compound 3)
[0068]
[0069] The synthesis method of compound A1 in this embodiment is as follows: acrylic acid, 6-aminohexanol and diethylamine are added sequentially to a three-necked flask purged with N2. After reacting for 24 hours under heating and stirring conditions, the product is separated from the reaction mixture through extraction, washing and drying steps to obtain the compound. The synthesis method of A1 is existing technology.
[0070] S1: Dissolve compound A1 in an ethanol solution and stir thoroughly until homogeneous; then add the polymerization inhibitor hydroquinone and compound B3, and stir thoroughly at room temperature until homogeneous before use;
[0071] The molar ratio of compound A1 to compound B3 is 4:1;
[0072] S2: Under stirring conditions, the mixture was heated to 65°C and reacted for 48 hours. After washing with ether and recrystallization with ethanol, the mixture was filtered and dried to obtain gel crosslinking agent compound 3.
[0073] Example 4
[0074] S1: Dissolve compound A in methanol solution and stir thoroughly until homogeneous; then add the polymerization inhibitor and compound B, and stir thoroughly at room temperature until homogeneous before use;
[0075] The molar mass ratio of compound A to compound B is 4 to 2:1;
[0076] S2: Under stirring conditions, heat to 40℃~65℃ and react for 12~48h. The gel crosslinking agent is obtained by washing with ether, recrystallizing with ethanol, filtration and drying.
[0077]
[0078] in, n=1~3; X=F, Cl, Br, I;
[0079]
[0080] Example 5
[0081] The high-temperature biodegradable gel plugging agent is composed of raw material formulations:
[0082] Propylene monomer 10.0wt%~15wt%
[0083] 1.0 wt% gel crosslinking agent
[0084] Initiator 0.01wt%~0.001wt%
[0085] The remainder is water.
[0086] Optionally, the high-temperature biodegradable gel plugging agent components are composed of raw material formulations:
[0087] 10.0 wt% of propylene monomer
[0088] 1.0 wt% gel crosslinking agent
[0089] Initiator 0.01wt%
[0090] The remainder is water.
[0091] Optionally, the high-temperature biodegradable gel plugging agent components are composed of raw material formulations:
[0092] 15% wt% of propylene monomer
[0093] 1.0 wt% gel crosslinking agent
[0094] Initiator 0.001 wt%
[0095] The remainder is water.
[0096] Optionally, the high-temperature biodegradable gel plugging agent components are composed of raw material formulations:
[0097] 12% wt% of propylene monomer
[0098] 1.0 wt% gel crosslinking agent
[0099] Initiator 0.05wt%
[0100] The remainder is water.
[0101] The propylene monomer is one or more of acrylamide, 2-acrylamide-2-methylpropanesulfonic acid, acrylic acid, acrylonitrile, etc.
[0102] The general structural formula of the gel crosslinking agent is shown in Formula I:
[0103]
[0104] in, n=1~3; X=F, Cl, Br, I;
[0105]
[0106] The initiator is one or more of ammonium persulfate and azobisisobutyramidine hydrochloride.
[0107] The biodegradable gel plugging agent experiments are shown in Table 1. Control experiment: gel crosslinking agent, control compound 1:
[0108]
[0109] The preparation method of the control crosslinking agent 1 is as follows: Appropriate amounts of 2-nitrobenzaldehyde, ethylene glycol, and methyl acrylate are added to a reaction vessel and stirred until homogeneous. A certain amount of sulfuric acid is then added, and the reaction is carried out at a suitable temperature for 48 hours. After the reaction is complete, the reaction mixture is subjected to extraction and separation to remove impurities and unreacted raw materials. Finally, the obtained product is purified and dried to obtain the final product. This preparation method is existing technology.
[0110] The infrared spectrum of the control compound 1 is shown below. Figure 3-4 As shown.
[0111] The infrared spectrum of the control compound 1 is as follows: Figure 3 As shown in the figure, 2973cm -1 The peak at 1693 cm⁻¹ represents the stretching vibration of the CH bond in the double bond. -1 The peak at 1423 cm⁻¹ represents the stretching vibration of the C=O group in the ester group. -1 The absorption peak at 1313 cm⁻¹ is the bending vibration absorption peak of the benzene ring. -1 The absorption peak at 1201 cm⁻¹ is the bending vibration of nitro-NO₂. -1 The absorption peak at 923 cm⁻¹ is the COC stretching vibration peak of the ether bond. -1 The peak at this position represents the vibrational absorption peak of the benzene ring. Based on the above analysis, it can be found that the spectrum contains absorption peaks for carbon-carbon double bonds, ester groups, ether bonds, nitro groups, and benzene rings, indicating that the synthesized substance conforms to the structure of the compound.
[0112] The NMR of the compound is as follows Figure 4 As shown in the figure, 7.79, 7.54, and 7.49 are the chemical shifts of the protons on the benzene ring, 6.44 is the chemical shift of the proton on the carbon atom connecting the benzene ring, 6.11 and 5.74 are the chemical shifts of the protons on the carbon-carbon double bond, 4.27 is the chemical shift of the proton on the carbon atom connecting the ester group, and 3.76 is the chemical shift of the proton on the carbon atom connecting the ether bond. It can be found that the chemical shifts of all the protons of this compound appear in the spectrum, indicating that the synthesized substance conforms to the structure of this compound.
[0113] Table 1 Biodegradable Gel Blocking Agents
[0114]
[0115] As shown in Table 1, compounds 1, 2, and 3, used as gel crosslinking agents and propylene monomers, with the initiator as a formulation, are applicable to biodegradable gel plugging agents. This system has an applicable temperature range of 90–120℃, an adjustable gelation time of 1.5–3 h, a controllable degradation time of 5–10 days, and a viscosity ≤10 mPa·s after degradation. In contrast, the control compound 1 system is insoluble in water, making it unsuitable for plugging operations in water-injection development oilfields. Furthermore, its degradation requires acid or light conditions and may damage the environment. Therefore, the temporary plugging agent system constructed using the gel crosslinking agent described in this invention has characteristics such as controllable gelation time, spontaneous degradation under certain temperature conditions, and low viscosity of the degraded product. Moreover, this gel degrades without the need for an additional breaker.
[0116] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.
Claims
1. A gel crosslinking agent, characterized in that: The general structural formula of the gel crosslinking agent is shown in Formula I: Equation I; where R2 = R3= , n=1~3; X=F, Cl, Br or I; R1= .
2. The gel crosslinking agent according to claim 1, characterized in that: In the gel crosslinking agent structure, R2= R3= X = F, Cl, Br, or I; R 1= 、 or .
3. A method for preparing a gel crosslinking agent according to claim 1, characterized in that: The synthetic route of the gel crosslinking agent is as follows: Where, R2= R3= , n=1~3; X=F, Cl, Br or I; R1= ; The preparation method of the gel crosslinking agent includes the following steps: S1: Dissolve compound A in an organic solvent and stir thoroughly until homogeneous; then add an appropriate amount of polymerization inhibitor and compound B, and stir thoroughly at room temperature until homogeneous before use; S2: Heat and stir, react for 12-48 h, wash with ether, recrystallize with ethanol, filter and dry to obtain gel crosslinking agent.
4. The method for preparing a gel crosslinking agent according to claim 3, characterized in that: The organic solvent is one or more of methanol or ethanol.
5. The method for preparing a gel crosslinking agent according to claim 3, characterized in that: In the gel crosslinking agent structure, R2= R3= X = F, Cl, Br, or I; R 1= 、 or .
6. The method for preparing a gel crosslinking agent according to claim 3, characterized in that: The molar mass ratio of compound A to compound B is 4~2:
1.
7. The method for preparing a gel crosslinking agent according to claim 3, characterized in that: The heating temperature in step S2 is 40~65℃.
8. The application of a gel crosslinking agent according to any one of claims 1-2 in the preparation of a high-temperature degradable gel plugging agent for oil fields.
9. The application according to claim 8, characterized in that: The high-temperature biodegradable gel plugging agent is composed of the following raw materials: Propylene monomers 10.0wt%~15wt% Gel crosslinking agent 1.0% wt% Initiator 0.01wt%~0.001wt% The remainder is water.
10. The application according to claim 9, characterized in that: The parameters of the high-temperature biodegradable gel plugging agent are: operating temperature of 90℃~120℃, gelation time of 1.5~3h, and degradation time of 7~8d.