A hydrogen sulfide scavenger for acid fracturing and a preparation method thereof

Abstract

The application discloses a hydrogen sulfide scavenger for acid fracturing and a preparation method thereof, and relates to the technical field of hydrogen sulfide scavengers, and comprises the following raw materials in parts by weight: 30-45 parts of aldehyde compounds, 30-45 parts of alcohol amine compounds, 10-18 parts of diamine bridging agents, 2-6 parts of solubilizing complexing agents, 20-30 parts of solvents and 1-3 parts of catalysts; the aldehyde compounds are divided into A component and B component, wherein the mass ratio of the A component to the B component is 2:1-3:1, the A component is paraformaldehyde, and the B component is at least one of glyoxal or glutaraldehyde. Through optimization of a molecular skeleton and introduction of a hydrophilic group, the hydrogen sulfide scavenger improves sulfur removal capacity and chemical stability in a strong acid environment, has good compatibility with acid liquid, effectively inhibits the generation of acid residues and insoluble precipitates, avoids secondary damage to a formation, and ensures high efficiency and mass transfer performance of the product through a preparation process.

Description

Technical Field

[0001] This invention relates to the field of hydrogen sulfide scavenging agents, specifically to a hydrogen sulfide scavenging agent for acid fracturing and its preparation method. Background Technology

[0002] Acid fracturing is a common production enhancement measure in oil and gas field development. Its principle is to utilize the chemical dissolution effect of acid on the rock to etch highly conductive fracture channels into the reservoir, thereby improving the oil and gas seepage environment. To ensure operational safety and protect downhole tubing equipment, various chemical additives are usually added to the acid system. However, during acid fracturing operations, hydrogen sulfide gas, either present in the formation fluids or generated by the acid-rock reaction, is often produced. Hydrogen sulfide is highly toxic and corrosive; if not treated, it not only seriously threatens the lives of on-site personnel but also causes hydrogen embrittlement or sulfide stress corrosion cracking of downhole tubing and surface facilities. Therefore, adding hydrogen sulfide scavengers to the acid is a common practice in the industry.

[0003] To control the risks associated with hydrogen sulfide, existing technologies typically employ triazine-based scavengers. While these scavengers exhibit some desulfurization capabilities in conventional neutral or weakly alkaline environments, they often demonstrate unstable physicochemical states during use in the highly acidic environments characteristic of acid fracturing operations. In actual pumping processes, when these scavengers come into contact with and mix with high-concentration acid solutions, they are highly susceptible to pH fluctuations and become ineffective, causing their hydrogen sulfide capture capacity to diminish before reaching the target formation. This fails to meet the purification requirements of deep wells, high-temperature environments, and high-sulfur conditions.

[0004] More seriously, in practical applications, it has been observed that when existing cleaning agents are mixed with acid, a large amount of flocculent matter or viscous solid precipitates easily form in the system. These insoluble substances not only make the acid system turbid and heterogeneous, affecting the smooth progress of the pumping process, but also, when this acid containing precipitates enters the formation, solid impurities remain in the fractures or pores newly etched by the acid, causing formation blockage. This blockage directly weakens the production enhancement effect of acid fracturing and causes irreversible secondary damage to the reservoir. In addition, in scenarios where increased dosage cannot be achieved due to cost or formulation requirements, the unit desulfurization capacity of existing products is often insufficient, resulting in excessive residual hydrogen sulfide in the treated fluid. Summary of the Invention

[0005] The purpose of this invention is to provide a hydrogen sulfide scavenger for acid pressure and its preparation method, thereby solving the problems existing in the background art.

[0006] To solve the above-mentioned technical problems, the present invention provides a hydrogen sulfide scavenger for acid fracturing, comprising the following raw materials in parts by weight: 30-45 parts of aldehyde compound, 30-45 parts of alkanolamine compound, 10-18 parts of diamine bridging agent, 2-6 parts of solubilizing compounding agent, 20-30 parts of solvent and 1-3 parts of catalyst;

[0007] Aldehyde compounds are divided into component A and component B, wherein the mass ratio of component A to component B is 2:1 to 3:1, component A is paraformaldehyde, and component B is at least one of glyoxal or glutaraldehyde.

[0008] Preferably, the alkanolamine compound is selected from at least one of monoethanolamine and monoisopropanolamine; the diamine bridging agent is selected from at least one of ethylenediamine, hexamethylenediamine, and amino-terminated polyoxypropylene ether with an average molecular weight of 200-400.

[0009] Preferably, the aldehyde compound in component A needs to undergo depolymerization pretreatment before being used in the preparation. The depolymerization pretreatment method is as follows: add component A to a reactor equipped with a reflux condenser, add 30-40% of the mass of component A in deionized water, turn on mechanical stirring, set the speed to 300-400 r / min, slowly raise the temperature to 50-60℃, adjust the pH value to 8-9, and stir at a constant temperature for 20-30 min to obtain a depolymerized dispersion.

[0010] Preferably, the solubilizing agent is selected from at least one of dodecyltrimethylammonium bromide, hexadecyltrimethylammonium chloride, and ethane-1,2-dimethylbis(N-dodecyl-N,N-dimethylammonium bromide); the solvent is selected from at least one of methanol, ethanol, or ethylene glycol.

[0011] Preferably, the catalyst is selected from at least one of sodium hydroxide, potassium carbonate, or triethylamine to adjust the alkaline environment of the reaction system.

[0012] Preferably, the alkanolamine compounds need to be dehydrated and purified before the reaction. The purification conditions are as follows: under a vacuum of 0.08 to 0.09 MPa, heat to 80 to 90°C and maintain for 15 to 20 minutes until no bubbles are generated.

[0013] A method for preparing a hydrogen sulfide scavenger for acid fracturing is also provided, characterized by comprising the following steps:

[0014] S1. Add the alkanolamine compound, solvent and catalyst to the reaction vessel, turn on the stirrer, set the speed to 200-250 r / min, control the temperature inside the vessel to 35-45℃, add the pretreated A component aldehyde compound by dropping, control the dropping time to 40-60 min, after the dropping is completed, keep the reaction at the temperature for 1-1.5 h, and obtain a monocyclic intermediate mixture;

[0015] S2. Take 10% to 20% of the solvent of the formula and add it to the aldehyde compound of component B for dilution. Then mix it with the diamine bridging agent and treat it in an ultrasonic disperser at a frequency of 40 to 50 kHz for 10 to 15 minutes to obtain the bridging premix.

[0016] S3. Slowly add the bridged premixed solution obtained in S2 into the reaction vessel in S1, adjust the stirring speed to 400-500 r / min, and carry out gradient heating. In the first stage, heat to 60-65℃ and react for 1-2 hours, during which the pH value of the reaction solution is monitored and maintained above 8. In the second stage, heat to 85-95℃ and reflux for 3-4 hours to promote the formation of closed ring of the bistriazine skeleton.

[0017] S4. After the reaction is complete, cool the reaction solution to 50-60°C, turn on the vacuum pump to perform reduced pressure distillation, control the vacuum degree to 0.05-0.08 MPa, remove the water and some low-boiling-point solvents generated in the reaction, until the distillate no longer increases.

[0018] S5. Release the vacuum, add the solubilizing compounding agent to the system, and replenish the solvent so that the total amount is consistent with the initial feed amount. Set the stirring speed to 150-200 r / min, mix evenly, and let stand for degassing for 2-4 hours. Filter to remove insoluble impurities to obtain the hydrogen sulfide scavenger for acid pressure.

[0019] Preferably, during the gradient heating process in S3, the pH value of the reaction solution is sampled and tested every 20 to 30 minutes. If the pH value is less than 8, a catalyst solution with a mass fraction of 20% to 30% is added to maintain an alkaline environment.

[0020] Preferably, during the S4 vacuum distillation process, the outlet temperature of the condenser is controlled at 5–10°C to ensure effective condensation and recovery of the distillate.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] By constructing a special molecular skeleton structure, the spatial distribution density of active sites within the molecule is effectively optimized, enabling each scavenger molecule to bind more hydrogen sulfide molecules. This increases the hydrogen sulfide capture load per unit mass of reagent without increasing the amount of chemical reagent used. The product generated by the reaction between the scavenger and hydrogen sulfide has good chemical stability and can maintain its binding state even in complex downhole thermodynamic environments, preventing the re-release of captured hydrogen sulfide and ensuring the thoroughness and durability of the desulfurization process. This meets the stringent safety requirements of high-sulfur oil and gas wells.

[0023] The formulation incorporates specific hydrophilic functional groups and solubilizing components, which improve the solubility and dispersion performance of the scavenger in strongly acidic base solutions. Under the high-temperature and strong acid environment of acid fracturing operations, it can maintain the integrity of the molecular structure and the homogeneity of the solution system, avoiding the generation of insoluble flocs, acid sludge, or precipitates due to agent decomposition or polymerization. This ensures that the acid solution will not clog reservoir pores due to foreign solid particles after entering the formation, thereby achieving efficient desulfurization while effectively avoiding secondary damage to formation permeability and protecting the reservoir's conductivity.

[0024] By employing a phased reaction process control strategy and utilizing specific physical dispersion methods and temperature gradient control, the orderly connection and structural reorganization of raw material molecules are achieved, ensuring that the final product has a regular microstructure and good mass transfer kinetics in the liquid phase. In practical applications, the scavenger can quickly penetrate the gas-liquid interface, contact with hydrogen sulfide, and react, shortening the reaction equilibrium time. This makes the scavenger particularly suitable for online mixing and injection processes with high requirements for treatment timeliness, improving the efficiency and safety of on-site operations. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a comparison chart showing the dissolution time of the hydrogen sulfide scavengers prepared in the examples and comparative examples in acid solution. Detailed Implementation

[0027] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0028] In the following examples and comparative examples, unless otherwise specified, the chemical reagents and raw materials used are all commercially available analytical grade or industrial grade products.

[0029] Example 1

[0030] This embodiment provides a hydrogen sulfide scavenger for acid fracturing, the raw material composition of which includes: 30 parts of aldehyde compound, 30 parts of alkanolamine compound, 10 parts of diamine bridging agent, 2 parts of solubilizing compounding agent, 20 parts of solvent (total) and 1 part of catalyst; wherein, the aldehyde compound is divided into component A paraformaldehyde and component B glyoxal, the mass ratio of component A to component B is 2:1; the alkanolamine compound is monoethanolamine; the diamine bridging agent is ethylenediamine; the solubilizing compounding agent is dodecyltrimethylammonium bromide; the solvent is methanol; and the catalyst is sodium hydroxide;

[0031] The preparation method of this hydrogen sulfide scavenger for acid fracturing includes the following steps:

[0032] S1. Add monoethanolamine, an alcoholic amine compound, to the reactor. Turn on the vacuum pump and dehydrate under reduced pressure at a vacuum of 0.085 MPa and a temperature of 85°C for 18 minutes until the system vacuum stabilizes and no bubbles are generated. Then cool down to 35°C, add 15 parts of methanol (reserve 5 parts for subsequent steps and compensation) and sodium hydroxide catalyst. Turn on the stirrer and set the speed to 200 r / min. Before use, paraformaldehyde, an aldehyde compound of component A, is pretreated by depolymerization. Add it to a reactor equipped with a reflux condenser and add 30% of its mass of deionized water. Slowly heat to 50°C at a speed of 300 r / min. Add 20% sodium hydroxide solution by mass to adjust the pH to 8. Stir at a constant temperature for 20 minutes to obtain a depolymerized dispersion. Add the pretreated component A to the main reactor by dropwise addition for 40 minutes. After the addition is complete, keep the reaction at the temperature for 1 hour to obtain a monocyclic intermediate mixture.

[0033] S2. Add 3 parts of solvent methanol to the aldehyde compound glyoxal in component B for dilution, then mix with the diamine bridging agent ethylenediamine, and treat in an ultrasonic disperser at a frequency of 40kHz for 10 minutes to obtain the bridging premix.

[0034] S3. Slowly add the bridged premixed solution obtained in S2 into the reactor of S1, adjust the stirring speed to 400 r / min, and carry out gradient heating. In the first stage, heat to 60℃ and react for 1 hour. Before the end of this stage, take a sample to test the pH value of the reaction solution. If it is less than 8, add sodium hydroxide to maintain alkalinity. In the second stage, heat to 85℃ and reflux for 3 hours to promote the formation of closed ring of the bistriazine skeleton.

[0035] S4. After the reaction is complete, the reaction solution is cooled to 50°C, and the vacuum pump is turned on to perform reduced pressure distillation, controlling the vacuum degree to 0.05MPa and the outlet temperature of the condenser tube to 5°C. During this process, water and some methanol produced by the reaction are distilled off, and a total of about 18 parts of distillate are collected (which, after testing, contain about 10 parts of methanol and about 8 parts of water).

[0036] S5. Remove the vacuum, add the remaining 2 parts of methanol and the 10 parts of methanol lost during distillation to the system (a total of 12 parts of methanol are added), then add the solubilizing compounding agent dodecyltrimethylammonium bromide, set the stirring speed to 150 r / min, mix evenly, let stand for 2 hours to degas, filter to remove insoluble impurities, and obtain the hydrogen sulfide scavenger for acid pressure.

[0037] Example 2

[0038] This embodiment provides a hydrogen sulfide scavenger for acid fracturing, the raw material composition of which includes: Aldehyde compounds, Alkylamine compounds, diamine bridging agents, Part of solubilizing compounding agent, Part of solvent and The catalyst consists of two components: component A (paraformaldehyde) and component B (glutaraldehyde), with a mass ratio of component A to component B of [missing information]. The alkanolamine compound selected is monoisopropanolamine; the diamine bridging agent selected is hexamethylenediamine; the solubilizing and compounding agent selected is hexadecyltrimethylammonium chloride; the solvent selected is ethylene glycol; and the catalyst selected is triethylamine.

[0039] The preparation method of this hydrogen sulfide scavenger for acid fracturing includes the following steps:

[0040] S1. Add isopropanolamine (an alcoholic amine compound), ethylene glycol (a solvent), and triethylamine (a catalyst) to the reaction vessel, and set the stirring speed to [speed value missing]. The temperature inside the reactor is controlled as follows: Component A, paraformaldehyde, underwent depolymerization pretreatment (addition of mass...). Deionized water, rotation speed ,temperature pH value ,time After that, add it dropwise, with a dropping time of [missing information]. Then, the heat preservation reaction A monocyclic intermediate mixture was obtained;

[0041] S2. Premix the diamine bridging agent hexamethylenediamine with the aldehyde compound glutaraldehyde (component B) in an ultrasonic disperser and set the frequency accordingly. deal with A bridged premix was prepared.

[0042] S3. Slowly add the bridged premix obtained in S2 to the reactor in S1, and adjust the stirring speed to... The reaction system undergoes a gradient heating process: the first stage involves heating to... reaction During this period, the pH value should be monitored and maintained at no less than [value missing]. The second phase of warming up to Reflux reaction ;

[0043] S4, the reaction solution is cooled to... ,exist Vacuum distillation under reduced pressure, with the condenser outlet temperature controlled at [temperature value missing]. The reaction removes water.

[0044] S5. Remove the vacuum, add the solubilizing compounding agent hexadecyltrimethylammonium chloride to the system, and... After mixing evenly at high speed, allow to stand to degas. After filtering to remove insoluble impurities, the finished product is obtained.

[0045] Example 3

[0046] This embodiment provides a hydrogen sulfide scavenger for acid fracturing, comprising the following raw materials: 38 parts aldehyde compounds, 38 parts alkanolamine compounds, 14 parts diamine bridging agents, 4 parts solubilizing compounding agents, 25 parts solvent, and 2 parts catalyst; wherein, the aldehyde compounds are divided into component A (paraformaldehyde) and component B (a mixture of glyoxal and glutaraldehyde in a 1:1 mass ratio), with a mass ratio of component A to component B of 2.5:1; the alkanolamine compounds are selected from a mixture of monoethanolamine and monoisopropanolamine in a 1:1 mass ratio; the diamine bridging agent is selected from polypropylene glycol bis(2-aminopropyl) ether (average molecular weight approximately 230); the solubilizing compounding agent is selected from bisquaternary ammonium salts; the solvent is selected from ethanol; and the catalyst is selected from potassium carbonate.

[0047] The preparation method of this hydrogen sulfide scavenger for acid fracturing includes the following steps:

[0048] S1. Add the alkanolamine compound, solvent, and catalyst to the reaction vessel, and stir at a certain speed. ,temperature Component A, paraformaldehyde, underwent depolymerization pretreatment (addition of mass...). Deionized water, rotation speed ,temperature pH value ,time Add the first dropwise, and the time between drops is... Insulation reaction A monocyclic intermediate mixture was obtained;

[0049] S2. Premix the diamine bridging agent polyetheramine with the aldehyde compound of component B, and set the frequency in an ultrasonic disperser. deal with A bridged premix was prepared.

[0050] S3. Add the bridged premix obtained in S2 to the reaction vessel in S1, and stir at a certain speed. Gradient heating: First stage reaction To ensure the pH level remains alkaline; second stage reflux reaction ;

[0051] S4, the reaction solution is cooled to... ,exist Vacuum distillation under reduced pressure, condenser outlet temperature Deep dehydration;

[0052] S5. Remove the vacuum and add the solubilizing compounding agent, bisquaternary ammonium salt. Stir well and let stand to remove bubbles. The finished product is obtained by filtration.

[0053] Example 4

[0054] This embodiment provides a hydrogen sulfide scavenger for acid fracturing, the raw material composition of which includes: Aldehyde compounds, Alkylamine compounds, diamine bridging agents, Part of solubilizing compounding agent, Part of solvent and Part of catalyst; wherein, the mass ratio of aldehyde compound A (paraformaldehyde) to component B (glyoxal) is [missing information]. Monoethanolamine is selected as the amine-based compound; ethylenediamine and hexamethylenediamine are selected as the bridging agents in a mass ratio of [missing value]:[missing value]. The mixture; the solubilizing agent is dodecyltrimethylammonium bromide; the solvent is methanol to ethylene glycol at a mass ratio of A mixture; sodium hydroxide was selected as the catalyst;

[0055] The preparation method of this hydrogen sulfide scavenger for acid fracturing includes the following steps:

[0056] S1. Add the alkanolamine compound, solvent, and catalyst to the reaction vessel, and stir at a certain speed. ,temperature Component A was added dropwise after standard depolymerization pretreatment. Insulation ;

[0057] S2. Ultrasonic treatment of the diamine bridging agent and component B at a frequency of... ,time ;

[0058] S3. Add the premixed solution from S2 to the reactor from S1, and rotate at a constant speed. Gradient heating: First stage reaction (pH monitoring); Second stage reflux reaction ;

[0059] S4, Cool down to , Vacuum distillation, condenser outlet ;

[0060] S5. Add a solubilizing compounding agent. Mix and let stand ,filter.

[0061] Example 5

[0062] This embodiment provides a hydrogen sulfide scavenger for acid fracturing, comprising the following raw materials: 35 parts aldehyde compounds, 32 parts alkanolamine compounds, 12 parts diamine bridging agents, 5 parts solubilizing agents, 28 parts solvent, and 2.5 parts catalyst; wherein the mass ratio of paraformaldehyde (component A) to glutaraldehyde (component B) is 2.8:1; the alkanolamine compound is monoisopropanolamine; the diamine bridging agent is hexamethylenediamine; the solubilizing agent is ethane-1,2-dimethylbis(N-dodecyl-N,N-dimethylammonium bromide), specifically ethane-1,2-dimethylbis(N-dodecyl-N,N-dimethylammonium bromide); the solvent is ethanol; and the catalyst is potassium carbonate.

[0063] The preparation method of this hydrogen sulfide scavenger for acid fracturing includes the following steps:

[0064] S1. Add the alkanolamine compound, solvent, and catalyst to the reactor, and rotate... ,temperature Component A was added dropwise after pretreatment. Insulation ;

[0065] S2. Ultrasonic treatment of the diamine bridging agent and component B at a frequency of... ,time ;

[0066] S3. Add the premixed solution from S2 to the reactor from S1, and rotate at a constant speed. Gradient heating: First stage reaction (Maintaining pH alkalinity); Second stage reflux reaction ;

[0067] S4, Cool down to , Vacuum distillation, condenser outlet ;

[0068] S5. Add a solubilizing compounding agent. Mix and let stand ,filter.

[0069] Comparative Example 1

[0070] This comparative example provides a conventional hydrogen sulfide scavenging agent for acid fracturing, representing the prior art. The main component of this scavenging agent is a traditional triazine desulfurizer (1,3,5-tris(2-hydroxyethyl)hexahydro-S-triazine). Its preparation process does not involve the addition of diamine bridging agents or the cross-linking reaction of component B aldehyde compounds; it is prepared solely from monoethanolamine and paraformaldehyde in a conventional molar ratio. The product was obtained by condensation, and without the ultrasonic premixing step S2 and the gradient temperature closed-loop control in Example 1, it was directly synthesized in one step.

[0071] Comparative Example 2

[0072] This comparative example provides a hydrogen sulfide scavenger for acid fracturing to verify the necessity of ultrasonic dispersion treatment in step S2; its raw material composition is exactly the same as that of Example 1, and the main difference in preparation method is that in step S2, the diamine bridging agent and the aldehyde compound of component B are only subjected to simple mechanical stirring ( (The process is carried out without using an ultrasonic disperser; the remaining steps are consistent with Example 1.)

[0073] Comparative Example 3

[0074] This comparative example provides a hydrogen sulfide scavenger for acid fracturing, used to verify the key role of the gradient temperature process in step S3; its raw material composition is exactly the same as that of Example 1, the main difference in preparation method is that the first stage of low-temperature reaction is not carried out in step S3. Instead, the mixture is directly and rapidly heated to... Reflux reaction The remaining steps are consistent with those in Example 1.

[0075] Performance testing and effect analysis

[0076] To objectively evaluate the practical application effect of the hydrogen sulfide scavengers prepared in the above embodiments and comparative examples, the following performance tests were conducted under a simulated acid fracturing environment:

[0077] Hydrogen sulfide removal rate test: A closed reactor containing... The simulated gas sample was used to prepare the cleaning agent according to... Increased injection volume, in The reaction Determine the remaining Concentration and removal rate were calculated;

[0078] Acid resistance stability (acid slag) test: The cleaning agent is applied according to... Join In acid, Let stand in a constant temperature water bath Observe the appearance of the acid solution and record whether there is turbidity, layering or precipitation.

[0079] Dissolution and dispersibility test: Observe the initial dispersion state of the cleaning agent after adding acid solution, and record the time required for complete dissolution;

[0080] The test data statistics are shown in the table below:

[0081]

[0082] Results analysis:

[0083] High efficiency of dual-core structure: Examples 1-5 The removal rate remained stable at The above figures are significantly higher than those of Comparative Example 1; this fully demonstrates that the bistriazine skeleton constructed in this invention has a higher density of active nitrogen sites, and the introduction of diamine bridging agents has successfully achieved molecular-level capacity expansion, solving the problem of limited capacity of traditional scavengers.

[0084] The necessity of ultrasonic pretreatment: Comparing Example 1 and Comparative Example 2, it can be seen that the lack of ultrasonic treatment leads to a decrease in removal rate and a decrease in acid resistance. This is because simple mechanical stirring cannot make the bridging agent and aldehydes uniformly associate at the microscopic level, resulting in some molecules failing to form a perfect bicyclic structure, or even producing irregular polymers, thus exhibiting slight turbidity under acidic conditions.

[0085] The importance of gradient heating: Compared with Comparative Example 3, direct high temperature reaction resulted in a small amount of flocculent matter in the product and a reduced removal rate; this shows that the first stage of gradient heating is crucial for the adjustment of molecular conformation and pre-reaction. Direct high temperature can lead to an overly vigorous reaction, with some intermediates undergoing side reactions or uncontrollable cross-linking, thus destroying the expected bistriazine closed-ring structure.

[0086] Scenarios adaptability of each embodiment: Example 3, due to the introduction of polyetheramine and bisquaternary ammonium salt, has the fastest dissolution rate and extremely high removal rate, showing the best comprehensive performance; Examples 2 and 5, by introducing long-chain structures, maintain high removal rates while exhibiting excellent acid resistance and stability, verifying the protective effect of hydrophobic side chains on the skeleton.

[0087] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments that can be applied to other fields. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A hydrogen sulfide scavenger for use in acid fracturing, characterized in that, The raw materials include the following components by weight: 30-45 parts of aldehyde compounds, 30-45 parts of alcohol amine compounds, 10-18 parts of diamine bridging agents, 2-6 parts of solubilizing complexing agents, 20-30 parts of solvents, and 1-3 parts of catalysts; The aldehyde compounds are divided into an A component and a B component, wherein the mass ratio of the A component to the B component is 2:1-3:1, the A component is paraformaldehyde, and the B component is at least one of glyoxal or glutaraldehyde; The preparation method of the hydrogen sulfide scavenger for acid fracturing comprises the following steps: S1, alcohol amine compounds, solvents and catalysts are added to a reaction kettle, the stirring paddle is turned on, the rotating speed is set to 200-250 r / min, the temperature in the kettle is controlled to 35-45 DEG C, the pretreated A component aldehyde compounds are added in a dropwise manner, the dropwise adding time is controlled to 40-60 min, after the dropwise adding is completed, heat preservation reaction is carried out, the heat preservation time is 1-1.5 h, and a monocyclic intermediate mixed solution is obtained; S2, 10%-20% of the formula amount of solvents is pre-added to the B component aldehyde compounds to dilute, then the B component aldehyde compounds are mixed with diamine bridging agents, the frequency of an ultrasonic dispersion machine is set to 40-50 kHz, and the mixed solution is treated for 10-15 min to prepare a bridging premix; S3, the bridging premix prepared in S2 is slowly added to the reaction kettle in S1, the rotating speed of the stirring is adjusted to 400-500 r / min, and gradient heating is carried out, the temperature is raised to 60-65 DEG C in the first stage, and the reaction is carried out for 1-2 h, during which the pH value of the reaction solution is monitored and maintained above 8; the temperature is raised to 85-95 DEG C in the second stage, and the reaction is carried out for 3-4 h to promote the double triazine skeleton to be closed to form; S4, after the reaction is completed, the reaction solution is cooled to 50-60 DEG C, a vacuum pump is started to carry out reduced pressure distillation, the vacuum degree is controlled to 0.05-0.08 MPa, the reaction generated water and part of the low boiling point solvents are removed, and the distillate is not increased any more; S5, the vacuum is released, the solubilizing complexing agent is added to the system, the solvents are supplemented to make the total amount consistent with the initial amount, the rotating speed of the stirring is set to 150-200 r / min, after the mixing is uniform, the system is statically deaerated for 2-4 h, and the insoluble impurities are removed by filtration, and the hydrogen sulfide scavenger for acid fracturing is obtained.

2. The hydrogen sulfide scavenger for acid fracturing according to claim 1, characterized in that, The alcohol amine compounds are at least one of monoethanolamine and monoisopropanolamine; and the diamine bridging agent is at least one of ethylenediamine, hexanediamine and an amino-terminated polyoxypropylene ether with an average molecular weight of 200-400.

3. The hydrogen sulfide scavenger for acid fracturing of claim 1, wherein, The A component aldehyde compounds need to be depolymerized and pretreated before being used for preparation, and the method for the depolymerization and pretreatment is as follows: the A component is added to a reaction kettle with a condensation reflux device, 30-40% of deionized water of the mass of the A component is added, the mechanical stirring is started, the rotating speed is set to 300-400 r / min, the temperature is slowly raised to 50-60 DEG C, the pH value is adjusted to 8-9, and constant temperature stirring treatment is carried out for 20-30 min to obtain a depolymerized and dispersed solution.

4. The hydrogen sulfide scavenger for acid fracturing of claim 1, wherein, The solubilizing complexing agent is at least one of dodecyltrimethylammonium bromide, hexadecyltrimethylammonium chloride and ethane-1,2-diylbis(N-dodecyl-N,N-dimethylammonium bromide); and the solvent is at least one of methanol, ethanol or ethylene glycol.

5. The hydrogen sulfide scavenger for acid fracturing of claim 1, wherein, The catalyst is at least one of sodium hydroxide, potassium carbonate or triethylamine, which is used to adjust the alkaline environment of the reaction system.

6. The hydrogen sulfide scavenger for acid fracturing of claim 1, wherein, The alcohol amine compound needs to be dehydrated and purified before the reaction, and the treatment conditions are as follows: heating to 80-90 ℃ under a vacuum degree of 0.08-0.09 MPa for 15-20 min until no bubbles are generated.

7. The hydrogen sulfide scavenger for acid fracturing of claim 1, wherein, During the gradient temperature rising process in S3, the pH value of the reaction solution is detected every 20-30 min, and if the pH value is less than 8, a catalyst solution with a mass fraction of 20%-30% is added dropwise to maintain the alkaline environment.

8. The hydrogen sulfide scavenger for acid fracturing of claim 7, wherein, During the reduced pressure distillation process in S4, the outlet temperature of the condenser is controlled at 5-10 ℃ to ensure effective condensation and recovery of the distillate.

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