Supramolecular descaling agent as well as preparation method and application thereof

Abstract

The invention provides a supramolecular descaling agent, which is obtained by preparing a supramolecular ligand aqueous solution from a polydentate ligand, a ligand auxiliary agent and water, and then compounding the supramolecular ligand aqueous solution, a surfactant, a dispersant and a solubilizer, the structure of the polydentate ligand is shown as a formula (I), r1 and R2 are independently selected from-H, a substituted or unsubstituted alkyl group, a substituted or unsubstituted carboxyalkyl group, a substituted or unsubstituted aryl alkyl group, a substituted or unsubstituted heteroaryl alkyl group and a substituted or unsubstituted heterocyclic alkyl group. The supramolecular descaling agent is obtained by compounding a multi-tooth chelating ligand and a special auxiliary agent, and by utilizing the ligand recognition function and the structural designability of the multi-tooth chelating ligand, various dirt such as rust dirt, crystal dirt, oil dirt and mud dirt on the surface of metal, especially insoluble dirt, are complexed and dispersed into a solution, so that the metal surface can be descaled; the problem of low descaling rate of insoluble scale in oilfield exploitation is solved.

Description

Technical Field

[0001] This invention relates to the field of oil and gas extraction engineering technology in the petroleum industry, specifically to a supramolecular descaling agent, its preparation method, and its applications. Background Technology

[0002] As oilfield development progresses into its later stages, injection pressure and water cut continuously increase. The large amounts of barium, strontium, and calcium ions in the oilfield water readily precipitate as carbonates or sulfates, forming scale in the formation, wellbore, equipment, and surface systems. This scale blocks oil and gas pores and channels, reducing reservoir permeability, decreasing oil and gas production, increasing energy consumption, and causing under-scale corrosion. This severely impacts normal oilfield production, reduces efficiency, and can even lead to the abandonment of injection wells. Barium and strontium scale, in particular, is insoluble in acid and has a hard texture, making it difficult to remove and posing a significant challenge to later-stage oilfield development. When scaling occurs in the wellbore, the flow space within the wellbore decreases, reducing the efficiency of the pump. Severe scaling can even lead to pump jamming and leakage, seriously affecting normal oilfield extraction operations.

[0003] In oilfield production, the main scale components are carbonate or sulfate precipitates of divalent cations such as calcium, barium, and strontium. To address the increasingly serious scaling problem, oilfields widely use scale inhibitors for scale prevention. However, once scale forms, it can only be removed by chemical (or mechanical) methods. Looking at scale control both domestically and internationally, research on scale inhibitors is relatively mature, with a wide variety available, but the application of scale removers is limited, their scale-dissolving effect is unsatisfactory, and their types are also limited. Sulfate scale, in particular, has extremely low solubility, is easily formed, difficult to dissolve, and is the most difficult to treat; currently, there is no mature and feasible removal technology. Existing scale removers all suffer from problems such as low solubility of sparingly soluble sulfate scale, large dosage requirements, and slow dissolution rates.

[0004] In recent years, supramolecular chemistry has developed rapidly, blurring the boundaries between organic chemistry, inorganic chemistry, biochemistry, and materials chemistry, and emphasizing supramolecular systems with specific structures and functions. Some atoms that make up supramolecular ligands have unsaturated outer electron orbitals. They continuously seek out metal atoms with free outer electrons in solution, borrowing electrons and orbitals from each other to form stable "marriage molecules" that transcend molecular boundaries—a process known as supramolecular selective assembly. This assembly forms a stable monolayer on the atomic metal surface, i.e., a thin and dense supramolecular film. The supramolecular selective assembly process vibrates, penetrates, disperses, and cleans various contaminants, dispersing solid particles into molecular or ionic states, forming water-soluble polycyclic complexes, ultimately achieving the cleaning of the inner surfaces of pipelines.

[0005] CN110684983B discloses a neutral descaling agent and its preparation method, including a supramolecular descaling agent monomer solution, a surfactant, and a pH adjuster. The supramolecular descaling agent monomer is prepared using a special raw material ratio. It is safe and long-lasting, and does not chemically react with scale or metal. Through dispersion and molecular assembly, it can peel off and decompose scale, and finally stably adhere to the metal surface. It can remove insoluble scale such as oil, mud, crystal scale, and rust that are difficult to remove with conventional chemical cleaning, and form a dense protective film. It can maintain the long-term stable operation of oil wells and prevent the formation of subsequent scale, thus achieving long-term descaling and scale inhibition.

[0006] CN106186372B discloses a supramolecular care agent, a zero-discharge system for heating circulating water, and a method of use. The supramolecular care agent comprises the following components in weight percentage: sodium alkylbenzene sulfonate 7%–10%, sodium polyacrylate 10%–12%, dodecyl dimethyl benzyl ammonium chloride 5%–6%, alkanolamide 2%–2.5%, fatty alcohol polyoxyethylene ether 4.5%–6%, cyanoacetic acid 4%–5%, benzotriazole 1%–1.5%, sodium tripolyphosphate 2%–3%, sodium silicate 2%–2.5%, trisodium phosphate 1%–1.5%, ethylene glycol 2%–3%, pyridoxine hydrochloride 1%–1.5%, disodium hydrogen phosphate 2%–2.5%, and the balance being water. This patented technology, by adding sodium polyacrylate to a supramolecular cleaning agent, enables scale-free operation under alkaline and medium-to-high concentration conditions. It also utilizes sodium alkylbenzene sulfonate to disperse microcrystals or sediment of calcium carbonate, calcium sulfate, and other salts in the circulating water without precipitation, thus achieving scale inhibition. Simultaneously, the fatty alcohol polyoxyethylene ether, combined with cyanoacetic acid, has a catalytic effect, accelerating the coordinated assembly of components such as trisodium phosphate, sodium silicate, and sodium polyacrylate, forming a complex and organized polymer that creates a supramolecular film on the metal surface, further delaying scale formation.

[0007] Currently, the use of supramolecular technology for descaling is still an emerging discipline. There are relatively few types of supramolecular agents available as descaling agents, and the formulation systems are still underdeveloped. In particular, when facing descaling applications in complex oilfield environments, developing supramolecular descaling agents with simpler formulations and processes, higher descaling efficiency, and environmental friendliness is an urgent problem to be solved. Summary of the Invention

[0008] This invention provides a supramolecular descaling agent, which is obtained by compounding a multidentate chelating ligand with a special additive. By utilizing the ligand recognition function and structural designability of the multidentate chelating ligand, various types of dirt such as rust, crystal scale, oil, and mud on the metal surface, especially insoluble scale, are complexed and dispersed into the solution, thus solving the problem of low descaling rate of insoluble scale in oilfield development.

[0009] The technical solution of the present invention is as follows:

[0010] A supramolecular descaling agent is obtained by preparing a supramolecular ligand aqueous solution by reacting a multidentate ligand, a ligand auxiliaries, and water, and then compounding the supramolecular ligand aqueous solution with a surfactant, a dispersant, and a solubilizer. The structure of the multidentate ligand is shown in formula (I).

[0011]

[0012] R1 and R2 are each independently selected from -H, substituted or unsubstituted alkyl, substituted or unsubstituted carboxylalkyl, substituted or unsubstituted arylalkyl, substituted or unsubstituted heteroarylalkyl, and substituted or unsubstituted heterocyclic alkyl.

[0013] Furthermore, R1 and R2 are each independently selected from -H, C1-C6 alkyl, C2-C6 carboxyalkyl, substituted or unsubstituted arylmethylene, substituted or unsubstituted heteroarylmethylene, or substituted or unsubstituted heterocyclic methylene.

[0014] Furthermore, R1 and R2 are each independently selected from -H, methyl, -CH2COOH, (phenylmethylene), (pyridylmethylene) or (N-methyl-pyrrolylmethylene).

[0015] Furthermore, the supramolecular ligand aqueous solution is obtained by loading the multidentate ligand, ligand auxiliaries, and water into a reaction vessel at a mass ratio of 1:(2-4):(6-8), heating to 40-60°C under stirring, and refluxing for 1-2 hours.

[0016] Furthermore, based on the total mass of the supramolecular ligand aqueous solution, the mass percentage of the surfactant is 2-4%.

[0017] Furthermore, based on the total mass of the supramolecular ligand aqueous solution, the mass percentage of the dispersant is 0.5-2%.

[0018] Furthermore, based on the total mass of the supramolecular ligand aqueous solution, the mass percentage of the solubilizer is 6-8%.

[0019] Furthermore, the ligand auxiliaries comprise at least one of monoethanolamine, diethanolamine, triethanolamine, diethylene glycolamine, isobutanolamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and pentaethylenehexamine.

[0020] In this invention, the hydroxyl group of the ligand aid can form hydrogen bonds with the carboxyl or nitrogen atom of the polydentate ligand, and the amino group of the ligand aid can form an acid-base reaction with the carboxyl group of the polydentate ligand, thereby further promoting intermolecular self-assembly and facilitating the formation of supramolecular structures. Therefore, by providing additional coordinating groups or altering the pH of the solution, the ligand aid helps the polydentate ligand more effectively bind to metal ions (such as calcium and magnesium) in the scale, forming stable complexes, thus aiding in the dissolution and removal of the scale. Furthermore, the ligand aid can also reduce descaling costs.

[0021] Furthermore, the surfactant comprises at least one of fatty alcohol polyoxyethylene ether and alkylphenol polyoxyethylene ether.

[0022] Furthermore, the alkylphenol polyoxyethylene ether is selected from at least one of dodecylphenol polyoxyethylene ether and nonylphenol polyoxyethylene ether.

[0023] In this invention, the main function of the surfactant is to reduce the surface tension of the descaling agent solution, thereby enhancing its wetting and penetration capabilities onto the scale surface. The surfactant can penetrate into the tiny gaps between the scale and the substrate, making it easier for the descaling agent to contact and act on the scale. Furthermore, the surfactant can form tiny bubbles or droplets in the descaling agent solution, helping to disperse and suspend the scale in the solution, facilitating subsequent cleaning and removal.

[0024] Furthermore, the dispersant comprises at least one of sodium polyacrylate, sodium pyrophosphate, and sodium hexametaphosphate.

[0025] In this invention, the main function of the dispersant is to prevent the re-aggregation and deposition of tiny particles formed during the descaling process. They can adsorb onto the surface of scale particles to form a protective film, maintaining a certain distance between the particles and thus peeling, dispersing, and loosening the scale. Adding a dispersant helps maintain the descaling effect of the descaling agent and prevents the formation of new scale deposits during the cleaning process.

[0026] Furthermore, the solubilizer comprises at least one of glycerol, propylene glycol, ethylene glycol, and trimethylolpropane.

[0027] In this invention, the solubilizer primarily has a polyhydroxy structure, and its main function is to increase the solubility of each component in the descaling agent, ensuring that the descaling agent remains homogeneous and stable during preparation and use. The solubilizer can form hydrogen bonds with water molecules, lowering the freezing point of water and raising its boiling point, thereby improving the physical properties of the descaling agent. Furthermore, the solubilizer can enhance the descaling agent's penetration and dissolution ability of scale, improving the descaling effect.

[0028] Furthermore, the preparation method of the multidentate ligand includes the following steps:

[0029] Step S1: Add 1 mole of ethylenediamine substitute and 2 moles of 2-chloromethylpyridine to the reaction vessel, then add 10 moles of acetonitrile, and stir at room temperature for 15-30 min;

[0030] Step S2: Add 1 to 1.2 molar amounts of potassium carbonate to the above reaction solution and reflux at 85 to 90°C for 12 to 24 hours;

[0031] Step S3: After the reaction is complete, the above reaction solution is filtered to remove solid impurities, and the obtained filtrate is distilled to remove the solvent. The resulting solid is the multidentate ligand.

[0032] Furthermore, the reaction equation for the polydentate ligand is as follows:

[0033]

[0034] The present invention also provides a method for preparing the aforementioned supramolecular descaling agent, comprising the following steps:

[0035] (1) The multidentate ligand, ligand auxiliaries and water are loaded into the reaction vessel, heated to 40-60°C under stirring, and refluxed for 1-2 hours to obtain a supramolecular ligand aqueous solution.

[0036] (2) Add surfactant to the above supramolecular ligand aqueous solution and stir at room temperature for 1 to 2 hours;

[0037] (3) Continue adding dispersant and stir at room temperature for 1 to 2 hours;

[0038] (4) Continue to add solubilizer and stir at room temperature for 1 to 2 hours to obtain the supramolecular descaling agent.

[0039] Furthermore, the preparation method of the supramolecular descaling agent includes the following steps:

[0040] (1) The multidentate ligand, ligand auxiliaries and water are loaded into the reaction vessel in a mass ratio of 1:(2~4):(6~8), and the temperature is raised to 40~60℃ under stirring. The reaction is refluxed for 1~2 hours to obtain a supramolecular ligand aqueous solution.

[0041] (2) Add 2-4 w% of surfactant to the above supramolecular ligand aqueous solution and stir at room temperature for 1-2 hours;

[0042] (3) Continue to add 0.5-2w% of dispersant and stir at room temperature for 1-2 hours;

[0043] (4) Continue to add 6-8 w% of solubilizer and stir at room temperature for 1-2 hours to obtain the supramolecular descaling agent.

[0044] The present invention also provides an application of the aforementioned supramolecular descaling agent, including but not limited to descaling operations in oilfield gathering and transportation pipelines.

[0045] Furthermore, the present invention provides an application of the aforementioned supramolecular descaling agent, wherein the supramolecular descaling agent is prepared into an aqueous solution with a mass fraction of 10-15%, and injected into the pipeline to be treated for soaking and descaling.

[0046] Furthermore, after the aqueous solution of the supramolecular descaling agent is subjected to descaling operation at a temperature of 40°C for 24 hours, the descaling rate is measured to be 85-95%, preferably 88-92%.

[0047] Furthermore, the descaling operation involves using the aqueous solution of the supramolecular descaling agent to remove carbonate or sulfate precipitates of divalent cations such as calcium, barium, and strontium.

[0048] The present invention has the following significant technical effects:

[0049] (a) The supramolecular descaling agent of this invention mainly utilizes the π-bonding interaction between the nitrogen-containing heterocycles and nitrogen-containing benzene rings of the polydentate ligand, as well as the acid-base or hydrogen bonding interaction between the carboxylic acid group of the polydentate ligand and the amino or hydroxyl group of the ligand auxiliary to form supramolecular aggregates. This invention "replaces" the scale on the metal surface through a supramolecular self-assembly film formation process. In addition to supramolecular self-assembly in the general sense, the polydentate ligand provided by this invention also utilizes the chelating effect of the "polydentate nitrogen" of the polydentate ligand on metal ions, further improving the descaling effect.

[0050] (b) The multidentate ligand supramolecular descaling agent of the present invention has selective assembly and ligand recognition functions, and achieves the stripping, decomposition and removal of sulfate insoluble scale through molecular assembly, dispersion, solubilization and emulsification processes.

[0051] (c) Compared to traditional chemical descaling agents, the multidentate ligand supramolecular descaling agent of this invention has a pH value between 7 and 8, is non-corrosive to metal surfaces, and is environmentally friendly and pollution-free. It also exhibits lower toxicity and better biodegradability. In use, the multidentate ligand supramolecular descaling agent is simply prepared as an aqueous solution and added to the system via a pump, enabling online cleaning and reducing operating costs.

[0052] (d) The supramolecular descaling agent of the present invention not only improves the efficiency and effectiveness of descaling operations, but also reduces the stringent requirements on the operating environment, reduces energy consumption and chemical usage, and provides strong technical support for the clean and efficient exploitation of oil fields, showing great application potential in the oil field field.

[0053] (e) The supramolecular descaling agent of the present invention has multiple advantages in terms of efficient descaling, environmental safety, and corrosion and scale prevention, which perfectly meets the urgent needs of oilfield production for efficient and green technologies. With the deepening of oilfield development and the strengthening of environmental protection policies, this descaling agent can not only effectively solve the descaling problems of water injection wells and oil wells and improve production efficiency, but also meet environmental protection standards and contribute to the sustainable development of oilfields. Detailed Implementation

[0054] The following specific embodiments further explain or illustrate the content of the present invention, but the embodiments should not be construed as limiting the scope of protection of the present invention.

[0055] Example

[0056] Example 1

[0057] A supramolecular descaling agent is prepared by formulating a supramolecular ligand aqueous solution with a multidentate ligand, a ligand auxiliaries, and water, and then compounding the supramolecular ligand aqueous solution with a surfactant, a dispersant, and a solubilizer. The structure of the multidentate ligand is shown below:

[0058]

[0059] The preparation method of supramolecular descaling agent is as follows:

[0060] (1) The multidentate ligand, ligand auxiliaries (a mixture of monoethanolamine and pentaethylenehexamine in a mass ratio of 1:1) and water were loaded into the reaction vessel in a mass ratio of 1:2:6. The mixture was heated to 40°C under stirring and refluxed for 2 hours to obtain a supramolecular ligand aqueous solution.

[0061] (2) Add 4 wt% dodecylphenol polyoxyethylene ether as a surfactant to the above supramolecular ligand aqueous solution and stir at room temperature for 2 hours;

[0062] (3) Continue to add 2wg% sodium hexametaphosphate as a dispersant and stir at room temperature for 2 hours;

[0063] (4) Continue to add 8 wt% ethylene glycol as a solubilizer and stir at room temperature for 2 hours to obtain supramolecular descaling agent 1.

[0064] Example 2

[0065] A supramolecular descaling agent is prepared by formulating a supramolecular ligand aqueous solution with a multidentate ligand, a ligand auxiliaries, and water, and then compounding the supramolecular ligand aqueous solution with a surfactant, a dispersant, and a solubilizer. The structure of the multidentate ligand is shown below:

[0066]

[0067] The preparation method of supramolecular descaling agent is as follows:

[0068] (1) The multidentate ligand, ligand auxiliaries (triethanolamine) and water were loaded into the reaction vessel in a mass ratio of 1:4:8. The mixture was heated to 60°C under stirring and refluxed for 1 hour to obtain a supramolecular ligand aqueous solution.

[0069] (2) Add 2 wt% nonylphenol polyoxyethylene ether as a surfactant to the above supramolecular ligand aqueous solution and stir at room temperature for 1 hour;

[0070] (3) Continue to add 0.5 wt% sodium polyacrylate as a dispersant and stir at room temperature for 1 hour;

[0071] (4) Continue to add 6 wt% glycerol as a solubilizer and stir at room temperature for 1 hour to obtain multidentate ligand supramolecular descaling agent 2.

[0072] Example 3

[0073] A supramolecular descaling agent is prepared by formulating a supramolecular ligand aqueous solution with a multidentate ligand, a ligand auxiliaries, and water, and then compounding the supramolecular ligand aqueous solution with a surfactant, a dispersant, and a solubilizer. The structure of the multidentate ligand is shown below:

[0074]

[0075] The preparation method of supramolecular descaling agent is as follows:

[0076] (1) The multidentate ligand, ligand auxiliaries (a mixture of diethanolamine and diethylenetriamine in a mass ratio of 2:1) and water were loaded into the reactor in a mass ratio of 1:3:8. The mixture was heated to 50°C under stirring and refluxed for 1.5 hours to obtain a supramolecular ligand aqueous solution.

[0077] (2) Add 2.5 wt% fatty alcohol polyoxyethylene ether as a surfactant to the above supramolecular ligand aqueous solution and stir at room temperature for 1.5 hours;

[0078] (3) Continue to add 1.5 wt% sodium pyrophosphate as a dispersant and stir at room temperature for 1 hour;

[0079] (4) Continue to add 6.5 wt% of trimethylolpropane as a solubilizer, stir at room temperature for 1.5 hours to obtain multidentate ligand supramolecular descaling agent 3.

[0080] Example 4

[0081] A supramolecular descaling agent is prepared by formulating a supramolecular ligand aqueous solution with a multidentate ligand, a ligand auxiliaries, and water, and then compounding the supramolecular ligand aqueous solution with a surfactant, a dispersant, and a solubilizer. The structure of the multidentate ligand is shown below:

[0082]

[0083] The preparation method of supramolecular descaling agent is as follows:

[0084] (1) The multidentate ligand, ligand auxiliary (diethylene glycolamine) and water were loaded into the reaction vessel in a mass ratio of 1:3:7. The mixture was heated to 50°C under stirring and refluxed for 1 hour to obtain a supramolecular ligand aqueous solution.

[0085] (2) Add 3 wt% fatty alcohol polyoxyethylene ether as a surfactant to the above supramolecular ligand aqueous solution and stir at room temperature for 2 hours;

[0086] (3) Continue to add 0.8 wt% sodium polyacrylate as a dispersant and stir at room temperature for 1.5 hours;

[0087] (4) Continue to add 7wt% propylene glycol as a solubilizer and stir at room temperature for 2 hours to obtain multidentate ligand supramolecular descaling agent 4.

[0088] Example 5

[0089] A supramolecular descaling agent is prepared by formulating a supramolecular ligand aqueous solution with a multidentate ligand, a ligand auxiliaries, and water, and then compounding the supramolecular ligand aqueous solution with a surfactant, a dispersant, and a solubilizer. The structure of the multidentate ligand is shown below:

[0090]

[0091] The preparation method of supramolecular descaling agent is as follows:

[0092] (1) The multidentate ligand, ligand auxiliaries (a mixture of isobutanolamine and triethylenetetramine in a mass ratio of 1 / 2) and water were loaded into the reactor in a mass ratio of 1:4:7. The mixture was heated to 50°C under stirring and refluxed for 1.5 hours to obtain a supramolecular ligand aqueous solution.

[0093] (2) Add 3.5 wt% fatty alcohol polyoxyethylene ether as a surfactant to the above supramolecular ligand aqueous solution and stir at room temperature for 1.5 hours;

[0094] (3) Continue to add 1 wt% sodium polyacrylate as a dispersant and stir at room temperature for 1 hour;

[0095] (4) Continue to add 7.5 wt% ethylene glycol as a solubilizer and stir at room temperature for 2 hours to obtain multidentate ligand supramolecular descaling agent 5.

[0096] Example 6

[0097] A supramolecular descaling agent is prepared by formulating a supramolecular ligand aqueous solution with a multidentate ligand, a ligand auxiliaries, and water, and then compounding the supramolecular ligand aqueous solution with a surfactant, a dispersant, and a solubilizer. The structure of the multidentate ligand is shown below:

[0098]

[0099] The preparation method of supramolecular descaling agent is as follows:

[0100] (1) The multidentate ligand, ligand auxiliary (tetraethylenepentamine) and water were loaded into the reaction vessel in a mass ratio of 1:4:7. The mixture was heated to 50°C under stirring and refluxed for 2 hours to obtain a supramolecular ligand aqueous solution.

[0101] (2) Add 3 wt% dodecylphenol polyoxyethylene ether as a surfactant to the above supramolecular ligand aqueous solution and stir at room temperature for 2 hours;

[0102] (3) Continue to add 1.5 wt% sodium polyacrylate as a dispersant and stir at room temperature for 2 hours;

[0103] (4) Continue to add 7wt% glycerol as a solubilizer and stir at room temperature for 1 hour to obtain multidentate ligand supramolecular descaling agent 6.

[0104] Example 7

[0105] A supramolecular descaling agent is prepared by formulating a supramolecular ligand aqueous solution with a multidentate ligand, a ligand auxiliaries, and water, and then compounding the supramolecular ligand aqueous solution with a surfactant, a dispersant, and a solubilizer. The structure of the multidentate ligand is shown below:

[0106]

[0107] (1) The multidentate ligand, ligand auxiliaries (a mixture of diethanolamine and tetraethylenepentamine in a mass ratio of 1:1) and water were loaded into the reactor in a mass ratio of 1:3:8. The mixture was heated to 60°C under stirring and refluxed for 1 hour to obtain a supramolecular ligand aqueous solution.

[0108] (2) Add 2.5 wt% nonylphenol polyoxyethylene ether as a surfactant to the above-mentioned supramolecular ligand aqueous solution and stir at room temperature for 1.5 hours;

[0109] (3) Continue to add 1.2 wt% sodium polyacrylate as a dispersant and stir at room temperature for 1 hour;

[0110] (4) Continue to add 6 wt% trimethylolpropane as a solubilizer and stir at room temperature for 1.5 hours to obtain multidentate ligand supramolecular descaling agent 7.

[0111] Comparative Example 1

[0112] Except for the absence of ligand auxiliaries (a mixture of diethanolamine and tetraethylenepentamine in a mass ratio of 1:1), the other components, their proportions, preparation methods, and conditions are the same as in Example 7.

[0113] (1) The multidentate ligand and water were loaded into the reactor at a mass ratio of 1:8. The mixture was heated to 60°C under stirring and refluxed for 1 hour to obtain a supramolecular ligand aqueous solution.

[0114] (2) Add 2.5 wt% nonylphenol polyoxyethylene ether as a surfactant to the above-mentioned supramolecular ligand aqueous solution and stir at room temperature for 1.5 hours;

[0115] (3) Continue to add 1.2 wt% sodium polyacrylate as a dispersant and stir at room temperature for 1 hour;

[0116] (4) Continue to add 6 wt% trimethylolpropane as a solubilizer and stir at room temperature for 1.5 hours;

[0117] The structure of the multidentate ligand is shown below:

[0118]

[0119] Comparative Example 2

[0120] Except for the absence of a dispersant (sodium polyacrylate), the other components, their proportions, preparation methods, and conditions are the same as in Example 7.

[0121] (1) The multidentate ligand, ligand auxiliaries (a mixture of diethanolamine and tetraethylenepentamine in a mass ratio of 1:1) and water were loaded into the reactor in a mass ratio of 1:3:8. The mixture was heated to 60°C under stirring and refluxed for 1 hour to obtain a supramolecular ligand aqueous solution.

[0122] (2) Add 2.5 wt% nonylphenol polyoxyethylene ether as a surfactant to the above-mentioned supramolecular ligand aqueous solution and stir at room temperature for 1.5 hours;

[0123] (3) Continue to add 6 wt% trimethylolpropane as a solubilizer and stir at room temperature for 1.5 hours;

[0124] The structure of the multidentate ligand is shown below:

[0125]

[0126] Test case

[0127] Descaling rate is tested according to the following industry standards:

[0128] The descaling rate was implemented in accordance with the "Technical Requirements for Chemical Descaling Agents in Oilfield Technical Systems" (Q / SY148-2007), and the experimental steps are as follows:

[0129] ① Select and clean several conical flasks and separatory funnels, fold and label the filter paper to be used, place the scale sample and filter paper in an oven (102℃) to dry for 2 hours, and weigh the filter paper as M0;

[0130] ② Weigh the dried scale sample and conduct a scale dissolution experiment (at the specified experimental temperature, scale sample mass M, supramolecular descaling agent dosage, deionized water to a final volume of 100 mL, and heating in a constant temperature water bath for 24 h), and perform a filtration experiment.

[0131] ③ Place the filtered filter paper with scale in an oven (102℃) and dry it for 6 hours. Weigh it as M1 and calculate its descaling rate.

[0132] ④ Formula for calculating descaling rate:

[0133]

[0134] The multidentate ligand supramolecular descaling agents obtained in Examples 1 to 7 and Comparative Examples 1 and 2 were prepared into aqueous solutions with a mass fraction of 10-15%. Barium sulfate scale samples were added and treated at 40°C for 24 hours. The results are shown in Table 1 below.

[0135] Table 1 shows the descaling efficiency results of the supramolecular descaling agents in Examples 1 to 7 and Comparative Examples 1 and 2.

[0136]

[0137] The supramolecular descaling agents of Examples 1-7 of the present invention all achieved good descaling rates, with a descaling rate of at least 87%. As shown in Table 1, in the molecular structure of the supramolecular descaling agents of Examples 1-7, in addition to the π-π bonds formed between aryl, heteroaryl, and heterocyclic groups that enhance intermolecular interactions and improve the stability and performance of the supramolecular descaling agents (such as enhancing their adsorption capacity and dispersion effect on scale), the presence of carboxylic acid functional groups can form hydrogen bonds with the hydroxyl groups of the ligands and produce acid-base reactions with the amino groups of the ligands, thereby further promoting intermolecular self-assembly and facilitating the formation of a more stable and efficient supramolecular structure. This supramolecular structure not only improves the adsorption and dispersion performance of the descaling agent but also enhances its stability and durability in complex environments.

Claims

1. A supramolecular descaling agent, characterized in that, A supramolecular ligand aqueous solution was prepared by reacting a multidentate ligand, a ligand auxiliaries, and water. This supramolecular ligand aqueous solution was then compounded with a surfactant, a dispersant, and a solubilizer. The structure of the multidentate ligand is shown in formula (I). R1 and R2 are each independently selected from -H, substituted or unsubstituted alkyl, substituted or unsubstituted carboxylalkyl, substituted or unsubstituted arylalkyl, substituted or unsubstituted heteroarylalkyl, and substituted or unsubstituted heterocyclic alkyl.

2. The supramolecular descaling agent according to claim 1, characterized in that, R1 and R2 are each independently selected from -H, C1-C6 alkyl, C2-C6 carboxyalkyl, substituted or unsubstituted arylmethylene, substituted or unsubstituted heteroarylmethylene, or substituted or unsubstituted heterocyclic methylene.

3. The supramolecular descaling agent according to claim 1 or 2, characterized in that, R1 and R2 are each independently selected from -H, methyl, -CH2COOH, 4. The supramolecular descaling agent according to claim 3, characterized in that, The supramolecular ligand aqueous solution is obtained by loading the multidentate ligand, ligand auxiliaries and water into a reaction vessel at a mass ratio of 1:(2-4):(6-8), heating to 40-60°C under stirring, and refluxing for 1-2 hours.

5. The supramolecular descaling agent according to claim 4, characterized in that, Based on the total mass of the supramolecular ligand aqueous solution, the surfactant accounts for 2-4% of the total mass.

6. The supramolecular descaling agent according to claim 5, characterized in that, The dispersant has a mass percentage of 0.5-2% based on the total mass of the supramolecular ligand aqueous solution.

7. The supramolecular descaling agent according to claim 6, characterized in that, Based on the total mass of the supramolecular ligand aqueous solution, the mass percentage of the solubilizer is 6-8%.

8. The supramolecular descaling agent according to claim 7, characterized in that, The ligand auxiliaries include at least one of monoethanolamine, diethanolamine, triethanolamine, diethylene glycolamine, isobutanolamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and pentaethylenehexamine.

9. A method for preparing the supramolecular descaling agent according to any one of claims 1-8, characterized in that, Includes the following steps: (1) The multidentate ligand, ligand auxiliaries and water are loaded into the reaction vessel, heated to 40-60°C under stirring, and refluxed for 1-2 hours to obtain a supramolecular ligand aqueous solution. (2) Add surfactant to the above supramolecular ligand aqueous solution and stir at room temperature for 1 to 2 hours; (3) Continue adding dispersant and stir at room temperature for 1 to 2 hours; (4) Continue to add solubilizer and stir at room temperature for 1 to 2 hours to obtain the supramolecular descaling agent.

10. The use of the supramolecular descaling agent according to any one of claims 1-8, characterized in that, This includes, but is not limited to, descaling operations on oilfield gathering and transportation pipelines.

Images