Gel crosslinking agent, preparation method and application in ultra-high temperature degradable gel plugging agent

Abstract

The application discloses a gel cross-linking agent, a preparation method and application in super-high-temperature degradable gel plugging agents, and a structure general formula of the gel cross-linking agent is shown as formula I. The gel cross-linking agent can be applied in the super-high-temperature degradable gel plugging agent without additional conditions, a three-dimensional network structure is formed through chemical cross-linking, under the action of an internal catalyst, weak bonds in the functional cross-linking agent are broken, the three-dimensional network structure is disintegrated, a linear low-molecular-weight water-soluble polymer generated is dissolved in formation water, a low-viscosity fluid is formed, and the subsequent water injection is not affected, so that the super-high-temperature oilfield well can be temporarily plugged and overhauled.

Description

Technical Field

[0001] This invention belongs to the field of oilfield chemistry and application, and relates to a gel crosslinking agent and its application in degradable gel plugging agents. Specifically, it relates to a crosslinking agent for gels, a preparation method, and its application in ultra-high temperature degradable gel plugging agents. 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 offer unique advantages for 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 achieve plugging effects 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. However, currently available similar gel-based plugging agents in China are difficult to apply for temporary plugging operations, facing problems such as difficulty in gel breaking, reservoir contamination, and high risks and difficulties in on-site construction. Summary of the Invention

[0004] The purpose of this invention is to overcome the problems of existing gel plugging agents in oilfields using ultra-high temperature water injection development mode, such as difficulty in breaking down the gel, inability to spontaneously degrade, and reservoir pollution. This invention provides a crosslinking agent for gels, a preparation method, and its application in ultra-high temperature degradable gel plugging agents.

[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] in:

[0008] R1 = Cn H 2n+1 R2 = C m H 2m+1 n = 2 to 6; m = 2 to 6;

[0009] x=1~6; y=1~6; z=1~6.

[0010] The gel crosslinking agent designed in this invention comprises a quaternary ammonium salt structure, ester groups, and a benzene ring tridented central core. This structure can self-degrade under certain temperature conditions without the need for additional breaker agents. 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 benzene ring tridented central core can improve the spatial structure of the crosslinking agent during the crosslinking process, ensuring its relative stability under ultra-high temperature conditions while still meeting the requirements for subsequent self-degradation.

[0011] Furthermore, in the structure of the gel crosslinking agent: n = m = 2 to 6.

[0012] Furthermore, in the structure of the gel crosslinking agent: x = y = z = 1 to 5.

[0013] This structure can form a more reasonable three-dimensional spatial structure during the cross-linking process, finding a balance between self-degradation and stability.

[0014] The second objective of this invention is to provide a method for preparing a gel crosslinking agent:

[0015] The synthetic route is as follows:

[0016]

[0017] in:

[0018] R1 = C n H 2n+1 R2 = C m H 2m+1 n = 2 to 6; m = 2 to 6;

[0019] x = 1 to 5;

[0020] X = F, Cl, Br, I;

[0021] The preparation method of the gel crosslinking agent includes the following steps:

[0022] S1: Dissolve compound A in an organic solvent and stir thoroughly until homogeneous; then add an appropriate amount of polymerization inhibitor and trihalobenzene, and stir thoroughly at room temperature until homogeneous before use;

[0023] S2: Heat and stir, react for 12-48 hours, wash with ether, recrystallize with ethanol, filter and dry to obtain gel crosslinking agent.

[0024] Furthermore, the organic solvent is one or more of methanol or ethanol.

[0025] Furthermore, in the structure of the gel crosslinking agent, n = m = 2 to 6.

[0026] Furthermore, the molar mass ratio of compound A to trihalobenzene is 6 to 3:1.

[0027] Furthermore, the heating temperature in step S2 is 40–65°C.

[0028] Furthermore, the polymerization inhibitor is a polyphenol or a phenothiazine, wherein the polyphenol is hydroquinone or catechol.

[0029] 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.

[0030] The third objective of this invention is to provide an application of a gel crosslinking agent in the formulation of an ultra-high temperature biodegradable gel plugging agent for oil fields.

[0031] The ultra-high temperature biodegradable gel plugging agent is composed of the following raw materials:

[0032] 10wt% to 15wt% of propylene monomers;

[0033] 1.0 wt% gel crosslinking agent;

[0034] Initiator 0.01wt%~0.001wt%;

[0035] The remainder is water.

[0036] Furthermore, the propylene monomer is one or more of acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, acrylic acid, acrylonitrile, etc.

[0037] Furthermore, the initiator is one or more of ammonium persulfate and azobisisobutyramidine hydrochloride.

[0038] Furthermore, the application temperature of the ultra-high temperature biodegradable gel plugging agent is 120℃~150℃.

[0039] Furthermore, the gelation time of the ultra-high temperature biodegradable gel plugging agent is 2h to 4h.

[0040] Furthermore, the ultra-high temperature biodegradable gel plugging agent has a degradation time of 7 to 10 days, and its viscosity is less than 10 mPa·s after complete degradation.

[0041] Compared with the prior art, the beneficial effects of the present invention are:

[0042] 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.

[0043] 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.

[0044] The application of the gel crosslinking agent of the present invention in ultra-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. It does not require backflow and does not affect subsequent water injection, and can realize temporary plugging and maintenance of ultra-high temperature oilfield wells. Attached Figure Description

[0045] Figure 1 The image shows the infrared spectrum of gel crosslinking agent 1.

[0046] Figure 2 The image shows the 1H NMR spectrum of gel crosslinking agent 1. Detailed Implementation

[0047] 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.

[0048] Example 1

[0049]

[0050] in:

[0051] R1 = C n H 2n+1 R2 = C m H 2m+1 n = 2 to 6; m = 2 to 6;

[0052] x = 1 to 5;

[0053] X = F, Cl, Br, I;

[0054] The preparation method of the gel crosslinking agent includes the following steps:

[0055] S1: Dissolve compound A in methanol solution and stir thoroughly until homogeneous; then add the polymerization inhibitor phenothiazine and trihalobenzene, and stir thoroughly at room temperature until homogeneous before use;

[0056] The molar mass ratio of compound A to trihalobenzene is 6:1;

[0057] S2: Under stirring conditions, heat to 40°C and react for 12 hours. The gel crosslinking agent is obtained by washing with ether, recrystallizing with ethanol, filtering and drying.

[0058] 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.

[0059] Example 2

[0060] (Synthesis of gel crosslinking agent 1)

[0061] S1: Compound Dissolve in methanol solution and stir thoroughly until homogeneous; then add the polymerization inhibitors phenothiazine and mesobacterium tribromobenzene, and stir thoroughly at room temperature until homogeneous before use;

[0062] The molar ratio of compound A1 to mesbromobenzene is 3:1;

[0063] S2: Under stirring conditions, the mixture was heated to 40°C and reacted for 12 hours. After washing with ether and recrystallizing with ethanol, the mixture was filtered and dried to obtain gel crosslinking agent 1.

[0064] Characterization of gel crosslinking agent 1 is as follows Figure 1 and 2 As shown.

[0065] refer to Figure 1 As shown, 3430cm -1 The characteristic absorption peak of NH is at 3110 cm⁻¹. -1 and 3066cm -1 The characteristic absorption peak for a carbon-carbon double bond (C=C) is located at 1710 cm⁻¹. -1 The vibration at this point is the stretching vibration of a carbon-carbon double bond; 1552 cm⁻¹ -1 The peak at 1401 cm⁻¹ represents the stretching vibration of the C-H bond in the double bond. -1 The absorption peak at 1093 cm⁻¹ is due to the deformation vibration of the methyl group. -1 The absorption peak at 884 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.

[0066] The proton NMR spectrum of the crosslinking agent is shown below. Figure 2 As shown in the figure, position 7.01 represents the chemical shift of the proton on the benzene ring structure; positions 6.41 and 6.07 represent the chemical shifts of the carbon-carbon double bond; position 3.67 represents the chemical shift of the proton connecting the ester group; and positions 3.35 and 1.41 represent the chemical shifts of the heptyl 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.

[0067] Example 3 (Synthesis of Gel Crosslinking Agent 2)

[0068] S1: Compound Dissolve in ethanol solution and stir thoroughly until homogeneous; then add the polymerization inhibitor hydroquinone and triiodobenzene, and stir thoroughly at room temperature until homogeneous before use;

[0069] The molar ratio of compound A2 to triiodobenzene is 3:1;

[0070] S2: Under stirring conditions, the mixture was heated to 50°C and reacted for 24 hours. After washing with ether and recrystallizing with ethanol, the mixture was filtered and dried to obtain gel crosslinking agent 2.

[0071] The synthesis method of A2 is as follows: Ethyl acrylate and dihexylamine are added to a reaction vessel in a molar ratio of 1:1 and reacted at a certain temperature for 48 hours. After the reaction is completed, the reaction mixture is extracted and separated to remove impurities and unreacted raw materials. Finally, the obtained product is recrystallized and dried to obtain the target product. The synthesis method of A2 is existing technology.

[0072] Example 4 (Synthesis of Gel Crosslinking Agent 3)

[0073] S1: Compound (CAS No.: 2426-54-2), compound compound Dissolve each ingredient separately in an ethanol solution, add the polymerization inhibitor hydroquinone, and stir thoroughly until homogeneous;

[0074] S2: Under stirring conditions, heat to 65°C and add triiodophenylethanol solution dropwise; then react for 48 h, wash with ether, recrystallize with ethanol, filter and dry to obtain gel crosslinking agent 3.

[0075] The molar ratio of compound A1:compound A3:compound A4:triiodobenzene is 1:1:1:1.

[0076] The synthesis method of compound A3 is as follows: Butyl acrylate and diethylamine are added to a reaction vessel in a molar ratio of 1:1 and reacted at a certain temperature for 48 hours. After the reaction is completed, the reaction mixture is extracted and separated to remove impurities and unreacted starting materials. Finally, the obtained product is recrystallized and dried to obtain the target product. The synthesis method of compound A3 is existing technology.

[0077] Example 5

[0078] The ultra-high temperature biodegradable gel plugging agent is composed of raw material formulations:

[0079] 10wt% to 15wt% of propylene monomer

[0080] 1.0 wt% gel crosslinking agent

[0081] Initiator 0.01wt%~0.001wt%

[0082] The remainder is water;

[0083] Optionally, the ultra-high temperature biodegradable gel plugging agent components are composed of raw material formulations:

[0084] 10 wt% of propylene monomer

[0085] 1.0 wt% gel crosslinking agent

[0086] Initiator 0.001 wt%

[0087] The remainder is water;

[0088] Optionally, the ultra-high temperature biodegradable gel plugging agent components are composed of raw material formulations:

[0089] 15wt% propylene monomer

[0090] 1.0 wt% gel crosslinking agent

[0091] Initiator 0.01wt%

[0092] The remainder is water.

[0093] The propylene monomer is one or more of acrylamide, 2-acrylamide-2-methylpropanesulfonic acid, acrylic acid, acrylonitrile, etc.

[0094] The general structural formula of the gel crosslinking agent is shown in Formula I:

[0095]

[0096] R1 = C n H 2n+1 R2 = C m H 2m+1n = 2 to 6; m = 2 to 6;

[0097] x=1~6; y=1~6; z=1~6.

[0098] The initiator is one or more of ammonium persulfate and azobisisobutyramidine hydrochloride.

[0099] The biodegradable gel plugging agent experiments are shown in Table 1. Control experiment gel crosslinking agent, control crosslinking agent 1:

[0100] Table 1 Biodegradable Gel Blocking Agents

[0101]

[0102] As shown in Table 1, gel crosslinking agents 1, 2, and 3, used as gel crosslinking agents and propylene monomers, with the initiator as the formulation, are applied in the biodegradable gel plugging agent. This system has an applicable temperature range of 120–150℃, an adjustable gelation time of 2–4 h, a controllable degradation time of 7–10 days, and a viscosity ≤10 mPa·s after degradation. In contrast, the control crosslinking agent 1 system, at a high temperature of 95℃, has a gelation time of 1.5 h, a self-degradation time of 7 days, and a viscosity below 10 mPa·s after complete degradation, but cannot gel under ultra-high temperature conditions. Therefore, the temporary plugging agent system constructed with the gel crosslinking agents described in this invention has the characteristics of controllable gelation time, spontaneous degradation under ultra-high temperature conditions, and low viscosity of the degraded product. Furthermore, this gel can degrade without the need for an additional breaker.

[0103] 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: Formula I, Where: R1=C n H 2n+1 R2=C m H 2m+1 n=2~6; m=2~6; In anions, X = F, Cl, Br, or I; The number of repeating units of the methylene group is x = 1~5.

2. The gel crosslinking agent according to claim 1, characterized in that: In the structure of the gel crosslinking agent: n=m=2~6.

3. The method for preparing a gel crosslinking agent according to claim 1, characterized in that: The synthetic route is as follows: ; in: R1=C n H 2n+1 ,R2=C m H 2m+1 ;n=2~6;m=2~6; The number of repeating units of the methylene group is x = 1~5; In anions, X = F, Cl, Br, or I; 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 trihalobenzene, 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 structure of the gel crosslinking agent, n=m=2~6.

6. The method for preparing a gel crosslinking agent according to claim 3, characterized in that: The molar mass ratio of compound A to trihalobenzene is 6~3:

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 the gel crosslinking agent according to claim 1 in ultra-high temperature biodegradable gel plugging agent for oil fields.

9. The application according to claim 8, characterized in that: The ultra-high temperature biodegradable gel plugging agent is composed of the following raw materials: 10wt%~15wt% propylene monomer; Gel crosslinking agent 1.0 wt%; Initiator 0.01wt%~0.001wt%; The remainder is water.

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