Functional cross-linking agent as well as preparation method and application thereof

Abstract

The invention discloses a functional cross-linking agent and a preparation method and application thereof, and relates to the technical field of oilfield chemistry and application, the structure of the functional cross-linking agent comprises a quaternary ammonium salt structure, an ester group and a conjugated non-planar central nucleus, no additional conditions such as illumination, acidic conditions or alkaline conditions are needed, and the functional cross-linking agent has good stability. The self-degradation can be realized under a certain temperature condition. The method is simple and reliable in technology, high in yield and suitable for large-scale industrial production. A three-dimensional network structure is formed through chemical crosslinking, weak bonds in the functional crosslinking agent are broken and the three-dimensional network structure is disintegrated under the action of a built-in catalyst, generated linear low-molecular-weight water-soluble polymers are dissolved in formation water to form low-viscosity fluid, flowback is not needed, and subsequent water injection is not affected; and temporary plugging maintenance and the like of a low-temperature oil field well can be realized.

Description

Technical Field

[0001] The invention relates to the field of oilfield chemistry and application technology, and in particular to a functional crosslinking agent and a preparation method and application thereof. Background Art

[0002] As the development of oil fields using the water injection development model continues to deepen, a large number of pressurized water injection wells need to be inspected and repaired every year, and the demand for operations is large. When conventional well-killing measures are implemented, the overflow volume is large when the tubing is lifted and lowered, the well control risk is high, and the return fluid treatment is difficult. At present, the general pressurized water injection well operation mainly adopts two methods: conventional operation after pressure relief and pressurized operation to ensure the normal inspection and repair of high-pressure water injection wells. Since the wellhead pressure of pressurized water injection wells in oil fields is generally high, and the tubing pressure is generally above 10MPa, when water is released and pressure is released, on the one hand, the drainage volume is very large and the cost of sewage treatment is high, and on the other hand, the operation efficiency is affected by the long release cycle. During the pressurized operation, the tubing is lifted and lowered, the operation process is complicated, the average well occupation time is long, and the operation cost is high.

[0003] Before gelation, polymer gel materials have the characteristics of good rheology and easy injection; after gelation, they have the characteristics of deformability and adjustable plugging strength. Therefore, polymer gel has unique advantages in plugging operations. Since the polymer gel material itself has high deformability and will not be restricted by the leakage channel, after injection, it can be cross-linked and copolymerized by the easy-to-flow polymer or monomer solution to form an immobile jelly or gel, which can produce a plugging effect in extremely small channels. This material is liquid before injection. After injection, under formation conditions, it is transformed into a solid gel with a three-dimensional network structure due to cross-linking, and has good plugging properties. However, the existing similar gel plugging agents in China are difficult to apply to temporary plugging operations. There are problems such as difficulty in breaking the gel and contaminating the reservoir. On-site construction is difficult and risky.

[0004] Patent document CN107619371B discloses a "o-nitrobenzene diacetal ethyl diacrylate and its preparation method and application in dual degradation performance crosslinking agent", which uses o-nitrobenzene formaldehyde, trimethyl orthoformate and hydroxyethyl acrylate as starting materials, and obtains the target product o-nitrobenzene diacetal ethyl diacrylate through a two-step substitution reaction. The o-nitrobenzene diacetal ethyl diacrylate contains an ether group in its structure, and its application temperature is 50°C to 90°C. It needs to be exposed to light and acid before it can be degraded. Summary of the invention

[0005] The purpose of the present invention is to provide a functional cross-linking agent and its preparation method and application, which can effectively overcome the problems of gel breaking difficulty, inability to spontaneously degrade, reservoir pollution, etc. of existing gel plugging agents in oil fields with low-temperature water injection development mode. To achieve the above purpose, the present invention provides the following technical solutions:

[0006] The first object of the present invention is to provide a functional cross-linking agent, the general structural formula of the cross-linking agent is as follows:

[0007]

[0008] Where:

[0009] R 1 =H、CH 3 ;

[0010] R 2 =CH 2 CH 2 , CH 2 CH 2 CH 2 、CH(CH 3 )CH 2 , CH 2 CH 2 CH 2 CH 2 ;

[0011]

[0012] X=F, Cl, Br, I.

[0013] Furthermore, the general structural formula of the cross-linking agent is as follows:

[0014]

[0015] Where:

[0016] R 1 =H;

[0017] R 2 =CH 2 CH 2 CH 2 、CH(CH 3 )CH 2 ;

[0018]

[0019] X=F, Cl, Br, I.

[0020] The second object of the present invention is to provide a method for preparing a functional crosslinking agent, the method comprising the following steps:

[0021] Step S1, dissolving alkenyl tertiary amine ester compound A in an organic solvent, stirring well, then adding appropriate amount of polymerization inhibitor and halogenated alkyl compound B, stirring well at room temperature for standby use;

[0022] Step S2: heating the mixture of step S1 under stirring conditions, then washing with ether, recrystallizing with ethanol, filtering and drying.

[0023] Furthermore, the synthesis route of the functional cross-linking agent is as follows:

[0024]

[0025] Where:

[0026] R 1 =H、CH 3 ;

[0027] R 2 =CH 2 CH 2 , CH 2 CH 2 CH 2 、CH(CH 3 )CH 2 , CH 2 CH 2 CH 2 CH 2 ;

[0028]

[0029] X=F, Cl, Br, I.

[0030] Furthermore, the synthesis route of the functional cross-linking agent is as follows:

[0031]

[0032] Where:

[0033] R 1 =H;

[0034] R 2 =CH 2 CH 2 CH 2 、CH(CH 3 )CH 2 ;

[0035]

[0036] X=F, Cl, Br, I.

[0037] Furthermore, the organic solvent is one or more of methanol or ethanol.

[0038] Furthermore, the molar mass ratio of the compound A to the compound B is 4 to 2:1.

[0039] Furthermore, the polymerization inhibitor is a polyphenol or phenothiazine; the polyphenol is hydroquinone or catechol.

[0040] Furthermore, the conditions of the heating reaction include: the reaction temperature is 40 to 65° C., and the reaction time is 12 to 48 hours.

[0041] The third object of the present invention is to provide an application of a functional cross-linking agent, wherein the functional cross-linking agent is applied to a low-temperature degradable gel plugging agent.

[0042] Technical effects and advantages of the present invention:

[0043] (1) The functional crosslinking agent designed by the present invention includes a quaternary ammonium salt structure, an ester group, and a conjugated non-planar central core, and can self-degrade under certain temperature conditions without additional conditions such as light, acidic conditions or alkaline conditions. This is because the quaternary ammonium salt structure can increase the hydrolysis rate of the adjacent ester group, thereby achieving the self-degradation performance that meets the requirements; the introduction of the conjugated non-planar central core can improve the self-stability of the crosslinking agent under low temperature conditions, but can also meet the requirements of self-degradation in the later stage.

[0044] (2) The method of the present invention can prepare a functional cross-linking agent with good performance, and the technology is simple and reliable, with high yield, and is suitable for large-scale industrial production.

[0045] (3) The functional cross-linking agent of the present invention is used in the low-temperature degradable gel plugging agent to form a three-dimensional network structure through chemical cross-linking. Under the action of the built-in catalyst, the weak bonds in the functional cross-linking agent are broken, the three-dimensional network structure collapses, 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 subsequent water injection is not affected. Temporary plugging and maintenance of low-temperature oil field wells can be achieved.

[0046] Other features and advantages of the present invention will be described in the following description, and partly become obvious from the description, or be understood by implementing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0048] Figure 1FT-IR spectrum of the functional cross-linking agent 1 prepared in Example 1 of the present invention;

[0049] Figure 2 1HNMR spectrum of the functional cross-linking agent 1 prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0050] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not 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 are within the scope of protection of the present invention.

[0051] In order to solve the deficiencies of the prior art, the present invention provides the following technical solutions:

[0052] The first object of the present invention is to provide a functional crosslinking agent, the general structural formula of the functional crosslinking agent is as follows:

[0053]

[0054] Where:

[0055] R 1 =H、CH 3 ;

[0056] R 2 =CH 2 CH 2 , CH 2 CH 2 CH 2 、CH(CH 3 )CH 2 , CH 2 CH 2 CH 2 CH 2 ;

[0057]

[0058] X=F, Cl, Br, I.

[0059] The functional crosslinking agent structure includes a quaternary ammonium salt structure, an ester group, and a conjugated non-planar central core, which can self-degrade under certain temperature conditions without the need for additional breakers. The quaternary ammonium salt structure can increase the hydrolysis rate of the adjacent ester group, thereby achieving the self-degradation performance that meets the requirements; the introduction of the conjugated non-planar central core can improve the crosslinking agent's own stability under low temperature conditions, while meeting the requirements of self-degradation in the later stage.

[0060] Preferably, the functional cross-linking agent has the structural formula:

[0061] R 1 =H;

[0062] R 2 =CH 2 CH 2 CH 2 、CH(CH 3 )CH 2 ;

[0063]

[0064] X=F, Cl, Br, I.

[0065] The above-mentioned preferred functional cross-linking agent can form a more reasonable three-dimensional spatial structure during the cross-linking process, and find a satisfactory balance between self-degradation and stability.

[0066] The second object of the present invention is to provide a method for preparing a functional crosslinking agent, the preparation method comprising the following steps:

[0067] Step S1, dissolving compound A in an organic solvent, stirring well, then adding appropriate amount of polymerization inhibitor and compound B, stirring well at room temperature for standby use;

[0068] Step S2: heating the mixture of step S1 under stirring conditions, then washing with ether, recrystallizing with ethanol, filtering and drying to prepare a functional cross-linking agent.

[0069] Furthermore, the synthesis route of the functional cross-linking agent is as follows:

[0070]

[0071] Where:

[0072] R 1 =H、CH 3 ;

[0073] R 2 =CH 2 CH 2 , CH 2 CH 2 CH 2 、CH(CH 3 )CH 2 , CH 2 CH 2 CH 2 CH 2 ;

[0074]

[0075] X=F, Cl, Br, I;

[0076] Preferably, the functional cross-linking agent has the structural formula:

[0077] R 1 =H;

[0078] R 2 =CH 2 CH 2 CH 2 、CH(CH 3 )CH 2 ;

[0079]

[0080] X=F, Cl, Br, I.

[0081] Furthermore, the organic solvent is one or more of methanol or ethanol, and the amount thereof is equal to the mass of compound A.

[0082] Furthermore, the molar mass ratio of the compound A to the compound B is 4 to 2:1.

[0083] Furthermore, the inhibitor is a polyphenol or phenothiazine, and its added amount accounts for 0.1% to 0.5% of the total mass of the added substances (ie, compound A, compound B, organic solvent and inhibitor); the polyphenol is hydroquinone or catechol.

[0084] Furthermore, the conditions of the heating reaction include: the reaction temperature is 40 to 65° C., and the reaction time is 12 to 48 hours.

[0085] Example 1 (Synthesis of functional cross-linking agent 1)

[0086] Step S1: dissolving compound A1 in a methanol solution, stirring well, then adding a polymerization inhibitor (phenothiazine) and compound B1, stirring well at room temperature for later use;

[0087] The molar mass ratio of compound A1:compound B1 is 2:1;

[0088] Step S2: Under stirring conditions, the mixture of step S1 is heated to 40° C., reacted for 12 hours, washed with ether, recrystallized with ethanol, filtered and dried to prepare the functional crosslinking agent 1.

[0089] The synthetic route of functional cross-linker 1 is as follows:

[0090]

[0091] Figure 1The FT-IR spectrum of the functional cross-linking agent 1 prepared in Example 1 of the present invention is shown in Figure 1 Medium, 3270cm -1 The characteristic absorption peak of NH is at 3121cm -1 The =C—H vibration absorption peak of the carbon-carbon double bond is 2958cm -1 The peak at 1723cm is the stretching vibration peak of C—H in the double bond; -1 The stretching vibration peak of C=O in the ester bond is at 1471cm -1 The vibration absorption peaks of C=C are at 1278 and 1193 cm -1 The antisymmetric and symmetric vibration absorption peaks of C—O are at 975cm -1 The out-of-plane bending vibration peak of =C—H in the double bond is at . Through the infrared spectrum, it can be found that the characteristic absorption peaks of benzene ring, carbon-carbon double bond and ester group appear in the infrared spectrum of crosslinker 1, indicating that the target crosslinker has been successfully synthesized.

[0092] Figure 2 The functional cross-linking agent 1 prepared in Example 1 of the present invention is 1 H NMR spectrum, in Figure 2 Among them, 6.41, 6.12 and 5.83 are the chemical shifts of carbon-carbon double bonds, 4.59 is the chemical shift of protons connected to ester protons, 3.52, 3.30 and 4.50 are the chemical shifts of protons connected to nitrogen atoms, and 7.11 is the chemical shift of protons on the benzene ring. It can be seen from the spectrum that the synthesized cross-linker contains both carbon-carbon double bonds and ester groups, which is consistent with the structure of the expected designed cross-linker.

[0093] Example 2 (Synthesis of Functional Crosslinking Agent 2)

[0094] Step S1: dissolving compound A1 in an ethanol solution, stirring well, then adding a polymerization inhibitor (hydroquinone) and compound B2, stirring well at room temperature for later use;

[0095] The molar mass ratio of compound A1:compound B2 is 3:1;

[0096] Step S2: Under stirring conditions, the mixture of step S1 is heated to 50° C., reacted for 24 hours, washed with ether, recrystallized with ethanol, filtered and dried to prepare the functional crosslinking agent 2.

[0097] The synthetic route of functional cross-linking agent 2 is as follows:

[0098]

[0099] Example 3 (Synthesis of Functional Crosslinking Agent 3)

[0100] Step S1: dissolving compound A1 in an ethanol solution and stirring thoroughly; then adding a polymerization inhibitor (hydroquinone) and compound B3, stirring thoroughly at room temperature for later use;

[0101] The molar mass ratio of the compound A1:compound B3 is 4:1;

[0102] Step S2: Under stirring conditions, the mixture of step S1 is heated to 65° C., reacted for 48 hours, washed with ether, recrystallized with ethanol, filtered and dried to prepare the functional crosslinking agent 3.

[0103] The synthetic route of functional cross-linker 3 is as follows:

[0104]

[0105] Example 4

[0106] The experiment of low-temperature degradable gel plugging agent formed by cross-linking with the functional cross-linking agent of the present invention is shown in Table 1. Among them, the cross-linking agent of the control experiment is o-nitrobenzene diacetal ethyl diacrylate, and its structural formula is as follows:

[0107]

[0108] Table 1 Degradable gel plugging agent experiment

[0109]

[0110]

[0111] As can be seen from Table 1, functional crosslinker 1, functional crosslinker 2 and functional crosslinker 3 are used as functional crosslinkers with propylene monomers and initiators as a formula in a degradable gel plugging agent. The degradable gel plugging agent system has an applicable temperature range of 50 to 90°C, an adjustable gelling time of 2 to 4 hours, a controllable degradation time of 7 to 10 days, and a viscosity of ≤10 mPa·s after degradation. The control crosslinker 1 system is firstly insoluble in water and cannot be used for plugging operations in oil fields with a water injection development model. At the same time, its degradation requires acid or light conditions to degrade, and may also damage the environment. Therefore, the gel plugging agent system constructed by the functional crosslinker of the present invention has the characteristics of controllable gelling time, spontaneous degradation under certain temperature conditions, low viscosity of the product after degradation, and the gel can be degraded without the need for additional degelling agents.

[0112] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A functional crosslinking agent, characterized in that The general structural formula of the cross-linking agent is as follows: Where: R1=H or CH3; R2=CH2CH2, CH2CH2CH2, CH(CH3)CH2 or CH2CH2CH2CH2; X=F, Cl, Br or I.

2. A functional crosslinking agent according to claim 1, characterized in that: The general structural formula of the cross-linking agent is as follows: Where: R1=H; R2=CH2CH2CH2 or CH(CH3)CH2; X=F, Cl, Br or I.

3. A method for preparing a functional crosslinking agent as claimed in claim 1 or 2, characterized in that: The method comprises the following steps: Step S1, dissolving alkenyl tertiary amine ester compound A in an organic solvent, stirring well, then adding appropriate amount of polymerization inhibitor and halogenated alkyl compound B, stirring well at room temperature for standby use; Step S2: heating the mixture of step S1 under stirring conditions, then washing with ether, recrystallizing with ethanol, filtering and drying.

4. The method for preparing a functional crosslinking agent according to claim 3, characterized in that: The synthetic route of the functional cross-linking agent is as follows: Where: R1=H or CH3; R2=CH2CH2, CH2CH2CH2, CH(CH3)CH2 or CH2CH2CH2CH2; X=F, Cl, Br or I.

5. The method for preparing a functional crosslinking agent according to claim 4, characterized in that: The synthetic route of the functional cross-linking agent is as follows: Where: R1=H; R2=CH2CH2CH2 or CH(CH3)CH2; X=F, Cl, Br or I.

6. The method for preparing a functional crosslinking agent according to claim 3, characterized in that: The organic solvent is one or more of methanol or ethanol.

7. The method for preparing a functional crosslinking agent according to claim 3, characterized in that: The molar mass ratio of the compound A to the compound B is 4-2:

1.

8. The method for preparing a functional crosslinking agent according to claim 3, characterized in that: The polymerization inhibitor is polyphenol or phenothiazine; the polyphenol is hydroquinone or catechol.

9. The method for preparing a functional crosslinking agent according to claim 3, characterized in that: The conditions of the heating reaction include: reaction temperature of 40 to 65° C., and reaction time of 12 to 48 hours.

10. A use of the functional crosslinking agent as claimed in claim 1 or 2, characterized in that: The functional cross-linking agent is applied to a low-temperature degradable gel plugging agent.

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