High-efficiency sulfur-dissolving scale inhibitor and preparation method thereof

Abstract

The application discloses a high-efficiency sulfur-dissolving scale inhibitor and a preparation method thereof, and relates to the technical field of oil field chemicals. The sulfur-dissolving scale inhibitor comprises 37.5-52.5 parts of a main agent, 15.5-23 parts of a scale inhibitor, 7-17.5 parts of an auxiliary solvent, 5-20 parts of a stabilizer, 1-5 parts of a catalyst and 1-5 parts of an initiator; the main agent is composed of 27.5-37.5 parts of methyl phosphoramide, 7-10 parts of mercapto-oleic acid imidazoline and 3-5 parts of water; and the scale inhibitor is composed of 6.5-10 parts of hydroxyethyl methacrylate, 3.5-5.5 parts of methacryloyloxyethyl trimethyl ammonium chloride and 5.5-7.5 parts of methylene succinic acid. The sulfur-dissolving scale inhibitor has the advantages of high-efficiency sulfur-dissolving capacity, certain scale-removing capacity, the ability of dissolving scale in pipelines and equipment, the prevention of under-deposit corrosion, the addition of certain corrosion-inhibiting components, the inhibition of the corrosion of elemental sulfur, carbon dioxide and hydrogen sulfide, and wide application in gathering pipelines and equipment of high-sulfur gas fields.

Description

Technical Field

[0001] This invention relates to the field of oilfield chemical technology, and more specifically to a highly efficient sulfur-dissolving scale inhibitor and its preparation method. Background Technology

[0002] In recent years, driven by national strategic reserve needs and technological advancements, the efficient development of demanding gas fields to acquire more resources has become a crucial development direction. In my country, high-sulfur gas fields are widely distributed and possess enormous development potential. However, during the development of high-sulfur gas fields, elemental sulfur dissolved in natural gas often precipitates due to changes in temperature, pressure, and flow rate. This precipitated elemental sulfur can deposit on wellbore walls, gathering and transmission pipelines, and valves, causing pressure buildup and blockages in pipelines and equipment. Furthermore, in humid or water-containing environments, elemental sulfur can cause severe localized corrosion of carbon steel. Simultaneously, during oil and gas gathering and transportation, pipeline scaling is a frequent problem. The mixture of scale and elemental sulfur not only increases the risk of pipeline and equipment blockages but can also cause metal corrosion, leading to perforations and leaks in pipelines and equipment. This not only reduces the productivity of the gas field but also results in serious production safety issues. The deposition and scaling of elemental sulfur during the development and utilization of high-sulfur gas fields has become an important research topic and a major challenge that needs to be addressed to achieve increased production and efficiency in these fields. Therefore, developing a green, efficient, and economical sulfur-dissolving, scale-inhibiting, and corrosion-inhibiting agent is of significant engineering importance for solving the sulfur deposition and scaling problems in high-sulfur gas fields.

[0003] Currently, the most efficient sulfur solvent system for dissolving elemental sulfur is based on dimethyl disulfide (DMDS). However, due to the high toxicity, poor stability, poor compatibility with reagents, and high raw material costs of DMDS, it is difficult to promote its application in high-sulfur gas field development. Other sulfur solvent systems without DMDS, such as N,N-dimethylacetamide (DMA), ethyl dimethylbenzoate (DMB), and dimethyl carbonate (DMC), have much lower solubility for elemental sulfur than the DMDS system. Compounding low-toxicity, non-irritating sulfur solvents to obtain efficient and environmentally friendly sulfur solvents has become a major approach for researchers developing new sulfur solvents. The specific operation involves first using an alkaline sulfur solvent as the main agent, then extensively screening low-toxicity sulfur solvents, selecting the best-performing alkaline sulfur solvent formulation, compounding the two, and then compounding with another high-performing low-toxicity sulfur solvent, thus obtaining a three-component sulfur solvent system. The same method can be used to obtain four-component, five-component, and so on. However, while this method can yield low-toxicity sulfur solvents with high solubility, the large-scale compounding experiments, complex operation, and low controllability of results fail to meet the needs of actual production. Furthermore, some inorganic alkaline sulfur solvents with high solubility, although showing significant effects in laboratory tests, have highly alkaline solutions that are highly corrosive to actual production pipelines and equipment, thus making them unsuitable for field application. Many sulfur solvents also contain significant amounts of toxic components, failing to meet green environmental protection requirements. To date, no desulfurizing agents with scale inhibition properties are available on the market.

[0004] For example, the publication text of invention patent application CN116410721A discloses a sulfur solvent, a method for determining the sulfur dissolution capacity of the sulfur solvent, a preparation method, and its uses. It employs propylenediamine as the main solvent; under the conditions of sulfur solvent immersion, propylenediamine can undergo a complexation chemical reaction with deposited sulfur to form relatively stable organic complex sulfides, thereby converting elemental sulfur into sulfides. Additives are used to further improve the corrosion resistance, sulfur dissolution efficiency, and sulfur dissolution capacity of the sulfur solvent, thus achieving the effect of dispersing and dissolving deposited scale and achieving the purpose of unblocking. However, this sulfur dissolution method generates byproducts, increasing the complexity of the media environment. Furthermore, the compatibility of the additives and the main solvent, as well as the overall stability of the sulfur solvent, still require further verification.

[0005] For example, the publication text of invention patent application CN110964492A discloses a sulfur solvent, its preparation method, and its application. The sulfur solvent contains a highly branched polymer, a polar physical solvent, and an inorganic base catalyst. The highly branched polymer has a branching degree of 0.8–1 and a molecular weight of 400–10000. This sulfur solvent contains a highly branched polymer with a large number of branched units, numerous end groups, and a high number of amine groups, effectively improving its sulfur-dissolving ability and making it safer and more environmentally friendly. However, the production of this highly branched polymer is relatively complex, it cannot be directly obtained from the market, and its cost is high.

[0006] For example, the published text of invention patent application CN102408886A discloses a highly efficient, odorless sulfur dissolving agent composed of the following components: sodium hydroxide aqueous solution, sulfolane, N-methylpyrrolidone, and N,N-dimethylformamide. This sulfur dissolving agent has advantages such as a wide operating temperature range, maintaining high sulfur dissolving performance at low temperatures, low irritation, no odor, and low cost. It has excellent sulfur dissolving activity and can be widely used in the oilfield chemical industry. However, its main component is an alkaline inorganic solution, which can easily cause corrosion of pipelines and equipment.

[0007] For example, the publication text of invention patent application CN114763470A discloses a highly efficient sulfur dissolving agent, composed of the following components by weight: 42.5-62.5 parts main agent, 15-20 parts co-solvent, 1-5 parts catalyst, and 5-15 parts stabilizer. The main agent includes the following components by weight: 20-25 parts hexamethylphosphoric triamine, 10-15 parts 1,3-dimethyl-2-imidazolinone, 10-15 parts tetraethylenepentamine, and 2.5-7.5 parts water. The co-solvent is a primary amine solvent, the catalyst is an inorganic base, and the stabilizer is an organic alcohol. This sulfur dissolving agent is simple to prepare, low in cost, low in toxicity, environmentally friendly, odorless, and has high sulfur solubility and fast dissolution speed, with low corrosiveness to metals and polymer materials. However, its main agent contains hexamethylphosphoric triamine, which is identified as a potential carcinogen and can cause inflammation upon skin contact.

[0008] In summary, most sulfur dissolving agents suffer from problems such as high toxicity, complex manufacturing processes, complicated and uncontrollable compounding operations, high application costs, and significant susceptibility to environmental conditions. Furthermore, none of them possess scale inhibition capabilities. Therefore, a new type of sulfur dissolving and scale inhibitor that is economical, environmentally friendly, highly efficient, and stable is urgently needed in the actual production and operation of high-sulfur gas fields. Summary of the Invention

[0009] In order to overcome the defects and deficiencies in the existing technology, the present invention provides a highly efficient sulfur-dissolving scale inhibitor and its preparation method. The purpose of the present invention is to solve at least one of the technical problems mentioned above, and to provide a highly efficient sulfur-dissolving scale inhibitor suitable for sulfur deposition and scale inhibition in high-sulfur gas field gathering and transmission pipelines and equipment, while ensuring green and pollution-free operation.

[0010] The first aspect of this invention provides a highly efficient sulfur-dissolving scale inhibitor suitable for gathering and transmission pipelines and equipment in high-sulfur gas fields. This sulfur-dissolving scale inhibitor, in addition to having a high sulfur-dissolving capacity, also has a certain scale removal capacity, which can dissolve scale in pipelines and equipment, thus preventing under-scale corrosion. At the same time, it contains certain corrosion-inhibiting components, which have a certain inhibitory effect on corrosion by elemental sulfur, carbon dioxide, hydrogen sulfide, etc., and can be widely used in gathering and transmission pipelines and equipment in high-sulfur gas fields.

[0011] To address the problems existing in the prior art, the present invention is achieved through the following technical solution.

[0012] The first aspect of this invention provides a highly efficient sulfur-dissolving scale inhibitor, wherein the sulfur-dissolving scale inhibitor comprises, by weight, the following components: Main agent: 37.5 to 52.5 parts; 15.5 to 23 parts scale inhibitor; 7 to 17.5 parts of co-solvent; Stabilizer 5 to 20 parts; 1 to 5 parts catalyst; Initiator 1 to 5 parts; The main agent is composed of the following components in parts by mass: Methylphosphoramide (HMPT) 27.5 parts to 37.5 parts; 7 to 10 parts of mercaptooleic imidazoline; 3 to 5 parts water; The scale inhibitor is composed of the following components in parts by weight: Hydroxyethyl methacrylate 6.5 to 10 parts; 3.5 to 5.5 parts of methacryloyloxyethyltrimethylammonium chloride; 5.5 to 7.5 parts of methylene succinic acid; The co-solvent is a primary amine solvent, the stabilizer is an organic alcohol, the catalyst is an acid salt, and the initiator is a compound with a weak bond that is easily decomposed into active species.

[0013] More preferably, the sulfur-dissolving scale inhibitor comprises the following components by weight: Main agent: 44-49 parts; 17.5 to 21.5 parts scale inhibitor; 9 to 14 parts of co-solvent; Stabilizer 8 to 15 parts; 2 to 5 parts catalyst; Initiator 2 to 4 parts.

[0014] More preferably, the sulfur-dissolving scale inhibitor comprises, by weight, 48 parts of main agent, 21 parts of scale inhibitor, 13 parts of auxiliary solvent, 10 parts of stabilizer, 4 parts of catalyst, and 4 parts of initiator.

[0015] More preferably, the main agent, by weight, consists of 32.5 to 34.5 parts of methylphosphoramide, 8.5 to 9.5 parts of mercaptooleic imidazoline, and 3 to 5 parts of water.

[0016] More preferably, the main agent, by weight, consists of 34 parts of methylphosphoramide, 9 parts of mercaptooleic imidazoline, and 5 parts of water.

[0017] More preferably, the scale inhibitor, by weight, consists of 7.5 to 9.5 parts of hydroxyethyl methacrylate, 4 to 5 parts of methacryloyloxyethyltrimethylammonium chloride, and 6 to 7 parts of methylene succinic acid.

[0018] More preferably, the scale inhibitor, by weight, consists of 9 parts of hydroxyethyl methacrylate, 5 parts of methacryloyloxyethyltrimethylammonium chloride, and 7 parts of methylene succinic acid.

[0019] More preferably, the co-solvent is one or a mixture of two of ethylamine, benzylamine, and naphthylamine.

[0020] More preferably, the stabilizer is one or a mixture of methanol, ethanol, propanol, and glycerol.

[0021] More preferably, the catalyst is one or a mixture of sodium bisulfate, sodium bisulfite, potassium bisulfate, and potassium bisulfite.

[0022] More preferably, the initiator is ammonium persulfate.

[0023] The second aspect of this invention provides a method for preparing a highly efficient sulfur-dissolving scale inhibitor, the specific steps of which are as follows: S1. Place methylene dibutyric acid, methylphosphoramide, mercaptooleic acid imidazoline and deionized water into a container; S2. Place the container from step S1 in a heating jacket with a magnetic stirring function and heat it to 80°C. S3. Slowly and alternately add a mixed solution of methacryloyloxyethyltrimethylammonium chloride and hydroxyethyl methacrylate and the initiator to the container from step S2; after the addition is complete, react for 2 hours, and then cool to 35℃~40℃. S4. Add the co-solvent, stabilizer and catalyst sequentially to the container where the reaction in step S3 has been completed. Shake the container 4-5 times after each component is added to ensure thorough mixing before adding the next component. Finally, the sulfur-dissolving scale inhibitor is obtained.

[0024] Compared with the prior art, the beneficial technical effects of the present invention are as follows: 1. The main component of the sulfur-dissolving scale inhibitor of the present invention is composed of methylphosphoramide, mercaptooleic acid imidazoline, and water in a reasonable ratio. It has high sulfur dissolving efficiency, stable properties, simple preparation, low cost, and strong corrosion inhibition effect.

[0025] 2. The scale inhibitor of the present invention is prepared by mixing hydroxyethyl methacrylate, methacryloyloxyethyltrimethylammonium chloride, and methylene succinic acid in a reasonable ratio. The molecular structure of hydroxyethyl methacrylate (HEMA) is as follows: As a monomer, it has been widely used in oilfield chemistry as a scale inhibitor. Its molecule contains C=C double bonds that easily combine with other molecules, which can effectively dissolve scale-forming substances such as calcium carbonate. Moreover, its structure contains ester groups, which can effectively improve the flocculation of sulfur-soluble scale inhibitors at high Ca2+ concentrations, enhance the lattice distortion ability of sulfur-soluble scale inhibitors, and have good biodegradability.

[0026] The molecular structure of methacryloxyethyltrimethyl ammonium chloride (DMC) is as follows: It carries a positive charge, is highly water-soluble, and non-toxic. Currently, DMC polymers are widely used in the petrochemical industry. Because of its positive charge, it can attract negatively charged sandstone reservoir rocks, thus improving the adsorption performance of sulfur-dissolving scale inhibitors to some extent. Furthermore, the amino groups in DMC can improve the water solubility of scale inhibitors, and the quaternary ammonium salt structure also has a certain corrosion-inhibiting effect.

[0027] The molecular structure of itaconic acid (IA) is as follows: This component is an unsaturated diorganic carboxylic acid, which can provide a large number of carboxyl groups in sulfur-dissolving scale inhibitors. IA has good electronegativity. In addition, methylene dibutyric acid is currently commonly produced industrially using fermentation, which has the characteristics of low energy consumption and easy control, making it an excellent monomer for copolymer scale inhibitors.

[0028] 3. The co-solvent used in this invention is a primary amine solvent, which has a strong co-solvent effect and can effectively reduce the viscosity of the solution system after reaction with elemental sulfur.

[0029] 4. The stabilizer used in this invention is an organic alcohol, which can prevent the sulfur-dissolving scale inhibitor from being decomposed by light and heat, and can also play a certain role in anti-oxidative decomposition, effectively improving the stability of the system.

[0030] 5. The catalyst of this invention is an acidic salt, which has high catalytic efficiency, does not react chemically with other components of the sulfur dissolving scale inhibitor, and is non-volatile, non-corrosive, and non-toxic.

[0031] 6. Ammonium persulfate is selected as the initiator, which can provide external energy for the synthesis of sulfur-dissolving scale inhibitors, promote the breaking of π bonds in olefin monomers, and accelerate the reaction.

[0032] 7. The main agent system exhibits a synergistic effect. Hexamethylphosphoric triamine, as a strongly polar aprotic solvent, has high solubility for elemental sulfur when used alone, but it is easily decomposed at high temperatures. 1,3-Dimethyl-2-imidazolinone, as a high-boiling-point solvent, can improve the thermal stability of the system and form a soluble complex with sulfur molecules through π-π interactions. The two achieve synergistic effects through complementary solvation capabilities (hexamethylphosphoric triamine disrupts the sulfur crystal structure, while 1,3-dimethyl-2-imidazolinone stabilizes dissolved sulfur). The multiple amino functional groups of tetraethylenepentamine can form stable chelates with sulfur oxidation products, preventing secondary deposition. Its long-chain structure can also penetrate the micropores of sulfur scale, forming a "solvent-penetrating agent" synergistic system with hexamethylphosphoric triamine / 1,3-dimethyl-2-imidazolinone, accelerating the removal of sulfur scale.

[0033] 8. The high-efficiency sulfur-dissolving and scale-inhibiting agent provided by this invention overcomes the limitations of traditional sulfur-dissolving agents, possessing characteristics such as being green, efficient, stable, and pollution-free. While maintaining high sulfur-dissolving efficiency, it also exhibits certain corrosion inhibition and strong scale inhibition capabilities. Within the operating temperature range of high-sulfur gas field gathering and transmission pipelines and equipment, the sulfur-dissolving efficiency can reach or exceed 200%, and the scale inhibition efficiency can reach or exceed 95%. The high-efficiency sulfur-dissolving and scale-inhibiting agent provided by this invention can fully leverage the advantage of "one agent for multiple uses" when used in pipelines and equipment, significantly reducing the cost of reagent use, and can be widely applied in high-sulfur gas field gathering and transmission stations. Attached Figure Description

[0034] Figure 1 This is a schematic diagram showing the results of sulfur dissolution and scale inhibition efficiency of the sulfur-dissolving scale inhibitor obtained in Example 7 of this invention under different temperature conditions. Detailed Implementation

[0035] The following embodiments are merely exemplary embodiments of the present invention and are not intended to limit the present invention. The scope of protection of the present invention is defined by the claims. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention are within the scope of protection claimed by the present invention.

[0036] Example 1 As a preferred embodiment of the present invention, this embodiment discloses a highly efficient sulfur-dissolving scale inhibitor, which, by weight, comprises 37.5 parts of a main agent, 15.5 parts of a scale inhibitor, 17.5 parts of a co-solvent, 20 parts of a stabilizer, 5 parts of a catalyst, and 5 parts of an initiator; wherein, the main agent is composed of 27.5 parts of methylphosphoramide, 7 parts of mercaptooleic acid imidazoline, and 3 parts of water (deionized water can be selected); the scale inhibitor is composed of 6.5 parts of hydroxyethyl methacrylate, 3.5 parts of methacryloyloxyethyltrimethylammonium chloride, and 5.5 parts of methylene succinic acid.

[0037] The aforementioned co-solvent is a primary amine solvent, the stabilizer is an organic alcohol, the catalyst is an acid salt, and the initiator is a compound with a weak bond that is easily decomposed into active species.

[0038] In one embodiment of this invention, the co-solvent is one or a mixture of two of ethylamine, benzylamine, and naphthylamine. The stabilizer is one or a mixture of methanol, ethanol, propanol, and glycerol. The catalyst is one or a mixture of sodium bisulfate, sodium bisulfite, potassium bisulfate, and potassium bisulfite. The initiator is ammonium persulfate.

[0039] As an example of this embodiment, a method for preparing the above-mentioned sulfur-dissolving scale inhibitor is shown, and the specific steps are as follows: S1, methylene dibutyric acid, methylphosphoramide, mercaptooleic acid imidazoline and deionized water are put into a container; S2. Place the container from step S1 in a heating jacket with a magnetic stirring function and heat it to 80°C. S3. Slowly and alternately add a mixed solution of methacryloyloxyethyltrimethylammonium chloride and hydroxyethyl methacrylate, along with the initiator (ammonium persulfate), dropwise to the container from step S2. After the addition is complete, allow the reaction to proceed for 2 hours, and then cool to 35°C~40°C. S4. Add the co-solvent (ethylamine and benzylamine mixed in a 1:1 mass ratio), stabilizer (ethanol), and catalyst (potassium hydrogen sulfate) sequentially to the container after the reaction in step S3. Shake the container 4-5 times after each addition of a component to ensure thorough mixing before adding the next component. Finally, the sulfur-dissolving scale inhibitor is obtained.

[0040] As another example of this embodiment, a laboratory preparation method for the above-mentioned sulfur-dissolving scale inhibitor is provided. Specifically, 5.5 parts of methylene dibutyric acid, 27.5 parts of methylphosphoramide, 7 parts of mercaptooleic acid imidazoline, and 3 parts of deionized water are placed in a four-necked round-bottom flask. Two constant-pressure separatory funnels are prepared. One funnel contains a mixed solution of 3.5 parts of methacryloyloxyethyltrimethylammonium chloride and 6.5 parts of hydroxyethyl methacrylate, and the other funnel contains 5.0 parts of ammonium persulfate solution. After dilution, the funnels are connected to the four-necked flask. The heating mantle with magnetic stirring function is heated to 80°C. The two constant-pressure separatory funnels are adjusted, and the solution is slowly and alternately added dropwise to the round-bottom flask. After reacting for 2 hours, the solution is allowed to cool to 35°C. The resulting liquid is poured into a pear-shaped separatory funnel and 17.5 parts of ethylamine and benzylamine (in a mass ratio of 1:1) are added. The mixture is shaken 4-5 times and thoroughly stirred with a magnetic stirrer. Add 20 parts ethanol, shake 4-5 times, and stir thoroughly with a magnetic stirrer. Finally, add 5.0 parts potassium bisulfate, shake 4-5 times, and stir thoroughly with a magnetic stirrer to obtain the sulfur-dissolving scale inhibitor.

[0041] Example 2 As another preferred embodiment of the present invention, this embodiment discloses a highly efficient sulfur-dissolving scale inhibitor, which, by weight, comprises 49 parts of a main agent, 21.5 parts of a scale inhibitor, 9 parts of a co-solvent, 8 parts of a stabilizer, 2 parts of a catalyst, and 2 parts of an initiator; wherein, the main agent is composed of 34.5 parts of methylphosphoramide, 9.5 parts of mercaptooleic acid imidazoline, and 5 parts of water (deionized water can be selected); the scale inhibitor is composed of 9.5 parts of hydroxyethyl methacrylate, 5 parts of methacryloyloxyethyltrimethylammonium chloride, and 7 parts of methylene succinic acid.

[0042] The aforementioned co-solvent is a primary amine solvent, the stabilizer is an organic alcohol, the catalyst is an acid salt, and the initiator is a compound with a weak bond that readily decomposes into an active species. Specifically, the co-solvent is one or a mixture of two of ethylamine, benzylamine, and naphthylamine. The stabilizer is one or a mixture of methanol, ethanol, propanol, and glycerol. The catalyst is one or a mixture of sodium bisulfate, sodium bisulfite, potassium bisulfate, and potassium bisulfite. The initiator is ammonium persulfate.

[0043] As an example of this embodiment, a method for preparing the above-mentioned sulfur-dissolving scale inhibitor is shown, and the specific steps are as follows: S1, methylene dibutyric acid, methylphosphoramide, mercaptooleic acid imidazoline and deionized water are put into a container; S2. Place the container from step S1 in a heating jacket with a magnetic stirring function and heat it to 80°C. S3. Slowly and alternately add a mixed solution of methacryloyloxyethyltrimethylammonium chloride and hydroxyethyl methacrylate, along with the initiator (ammonium persulfate), dropwise to the container from step S2. After the addition is complete, allow the reaction to proceed for 2 hours, and then cool to 35°C~40°C. S4. Add the co-solvent (ethylamine and benzylamine mixed in a 1:1 mass ratio), stabilizer (ethanol), and catalyst (potassium hydrogen sulfate) sequentially to the container after the reaction in step S3. Shake the container 4-5 times after each addition of a component to ensure thorough mixing before adding the next component. Finally, the sulfur-dissolving scale inhibitor is obtained.

[0044] As another example of this embodiment, a laboratory preparation method for the above-mentioned sulfur-dissolving scale inhibitor is provided. Specifically, 7.0 parts of methylene dibutyric acid, 34.5 parts of methylphosphoramide, 9.5 parts of mercaptooleic acid imidazoline, and 5.0 parts of deionized water are placed in a four-necked round-bottom flask. Two constant-pressure separatory funnels are prepared. One funnel contains a mixed solution of 5.0 parts of methacryloyloxyethyltrimethylammonium chloride and 9.5 parts of hydroxyethyl methacrylate, and the other funnel contains 2.0 parts of ammonium persulfate solution. After dilution, the funnels are connected to the four-necked flask. The heating mantle with magnetic stirring function is heated to 80°C. The two constant-pressure separatory funnels are adjusted, and the solution is slowly and alternately added dropwise to the round-bottom flask. After reacting for 2 hours, the solution is allowed to cool to 35°C. The resulting liquid is poured into a pear-shaped separatory funnel and 9.0 parts of ethylamine and benzylamine (in a mass ratio of ethylamine:benzylamine = 1:1) are added. The mixture is shaken 4-5 times and thoroughly stirred with a magnetic stirrer. Add 8.0 parts of ethanol, shake 4-5 times, and stir thoroughly with a magnetic stirrer. Finally, add 2.0 parts of potassium bisulfate, shake 4-5 times, and stir thoroughly with a magnetic stirrer to obtain the sulfur-dissolving scale inhibitor.

[0045] Example 3 As another preferred embodiment of the present invention, this embodiment discloses a highly efficient sulfur-dissolving scale inhibitor, which, by weight, comprises 52.5 parts of a main agent, 23 parts of a scale inhibitor, 7 parts of a co-solvent, 5 parts of a stabilizer, 1 part of a catalyst, and 1 part of an initiator; wherein, the main agent is composed of 37.5 parts of methylphosphoramide, 10 parts of mercaptooleic acid imidazoline, and 5 parts of water (deionized water can be selected); the scale inhibitor is composed of 10 parts of hydroxyethyl methacrylate, 5.5 parts of methacryloyloxyethyltrimethylammonium chloride, and 7.5 parts of methylene succinic acid.

[0046] The aforementioned co-solvent is a primary amine solvent, the stabilizer is an organic alcohol, the catalyst is an acid salt, and the initiator is a compound with a weak bond that readily decomposes into an active species. Specifically, the co-solvent is one or a mixture of two of ethylamine, benzylamine, and naphthylamine. The stabilizer is one or a mixture of methanol, ethanol, propanol, and glycerol. The catalyst is one or a mixture of sodium bisulfate, sodium bisulfite, potassium bisulfate, and potassium bisulfite. The initiator is ammonium persulfate.

[0047] As an example of this embodiment, a method for preparing the above-mentioned sulfur-dissolving scale inhibitor is shown, and the specific steps are as follows: S1, methylene dibutyric acid, methylphosphoramide, mercaptooleic acid imidazoline and deionized water are put into a container; S2. Place the container from step S1 in a heating jacket with a magnetic stirring function and heat it to 80°C. S3. Slowly and alternately add a mixed solution of methacryloyloxyethyltrimethylammonium chloride and hydroxyethyl methacrylate, along with the initiator (ammonium persulfate), dropwise to the container from step S2. After the addition is complete, allow the reaction to proceed for 2 hours, and then cool to 35°C~40°C. S4. Add the co-solvent (ethylamine), stabilizer (methanol), and catalyst (potassium hydrogen sulfate) sequentially to the container where the reaction in step S3 has been completed. Shake the container 4-5 times after each addition of a component to ensure thorough mixing before adding the next component. Finally, the sulfur-dissolving scale inhibitor is obtained.

[0048] As another example of this embodiment, a laboratory preparation method for the above-mentioned sulfur-dissolving scale inhibitor is provided. Specifically, 7.5 parts of methylene dibutyric acid, 37.5 parts of methylphosphoramide, 10.0 parts of mercaptooleic acid imidazoline, and 5.0 parts of deionized water are placed in a four-necked round-bottom flask. Two constant-pressure separatory funnels are prepared. One funnel contains a mixed solution of 5.5 parts of methacryloyloxyethyltrimethylammonium chloride and 10.0 parts of hydroxyethyl methacrylate, and the other funnel contains 1.0 part of ammonium persulfate solution. After dilution, the funnels are connected to the four-necked flask. The heating mantle with magnetic stirring function is heated to 80°C. The two constant-pressure separatory funnels are adjusted, and the solution is slowly and alternately added dropwise to the round-bottom flask. After reacting for 2 hours, the solution is allowed to cool to 35°C. The resulting liquid is poured into a pear-shaped separatory funnel and 7.0 parts of ethylamine are added. The mixture is shaken 4-5 times and stirred thoroughly with a magnetic stirrer. Then, 5.0 parts of methanol are added, and the mixture is shaken 4-5 times and stirred thoroughly with a magnetic stirrer. Finally, add 1.0 part of sodium bisulfate, shake 4-5 times, and use a magnetic stirrer to mix thoroughly to obtain the sulfur-dissolving scale inhibitor.

[0049] Example 4 As another preferred embodiment of the present invention, this embodiment discloses a highly efficient sulfur-dissolving scale inhibitor, which, by weight, comprises 44 parts of a main agent, 17.5 parts of a scale inhibitor, 14 parts of a co-solvent, 15 parts of a stabilizer, 5 parts of a catalyst, and 4 parts of an initiator; wherein, the main agent is composed of 32.5 parts of methylphosphoramide, 8.5 parts of mercaptooleic acid imidazoline, and 3 parts of water (deionized water can be selected); the scale inhibitor is composed of 7.5 parts of hydroxyethyl methacrylate, 4 parts of methacryloyloxyethyltrimethylammonium chloride, and 6 parts of methylene succinic acid.

[0050] The aforementioned co-solvent is a primary amine solvent, the stabilizer is an organic alcohol, the catalyst is an acid salt, and the initiator is a compound with a weak bond that readily decomposes into an active species. Specifically, the co-solvent is one or a mixture of two of ethylamine, benzylamine, and naphthylamine. The stabilizer is one or a mixture of methanol, ethanol, propanol, and glycerol. The catalyst is one or a mixture of sodium bisulfate, sodium bisulfite, potassium bisulfate, and potassium bisulfite. The initiator is ammonium persulfate.

[0051] As an example of this embodiment, a laboratory preparation method for the above-mentioned sulfur-dissolving scale inhibitor is provided. Specifically, 6.0 parts of methylene dibutyric acid, 32.5 parts of methylphosphoramide, 8.5 parts of mercaptooleic acid imidazoline, and 3.0 parts of deionized water are placed in a four-necked round-bottom flask. Two constant-pressure separatory funnels are prepared. One funnel contains a mixed solution of 4.0 parts of methacryloxyethyltrimethylammonium chloride and 7.5 parts of hydroxyethyl methacrylate, and the other funnel contains 4.0 parts of ammonium persulfate solution. After dilution, the funnels are connected to the four-necked flask. The heating mantle with magnetic stirring function is heated to 80°C. The two constant-pressure separatory funnels are adjusted, and the solution is slowly and alternately added dropwise to the round-bottom flask. After reacting for 2 hours, the solution is allowed to cool to 35°C. The resulting liquid is poured into a pear-shaped separatory funnel and 14.0 parts of benzylamine are added. The mixture is shaken 4-5 times and thoroughly stirred with a magnetic stirrer. Add 5.0 parts methanol, 5.0 parts glycerol, and 5.0 parts propanol, shake 4-5 times, and stir thoroughly with a magnetic stirrer. Finally, add 2.5 parts potassium bisulfite and 2.5 parts potassium bisulfate, shake 4-5 times, and stir thoroughly with a magnetic stirrer to obtain the sulfur-dissolving scale inhibitor.

[0052] Example 5 As another preferred embodiment of the present invention, this embodiment discloses a highly efficient sulfur-dissolving scale inhibitor, which, by weight, comprises 46.5 parts of a main agent, 19 parts of a scale inhibitor, 12 parts of a co-solvent, 11 parts of a stabilizer, 3 parts of a catalyst, and 3 parts of an initiator; wherein, the main agent is composed of 33.5 parts of methylphosphoramide, 9 parts of mercaptooleic acid imidazoline, and 4 parts of water (deionized water can be selected); the scale inhibitor is composed of 8 parts of hydroxyethyl methacrylate, 4.5 parts of methacryloyloxyethyltrimethylammonium chloride, and 6.5 parts of methylene succinic acid.

[0053] The aforementioned co-solvent is a primary amine solvent, the stabilizer is an organic alcohol, the catalyst is an acid salt, and the initiator is a compound with a weak bond that readily decomposes into an active species. Specifically, the co-solvent is one or a mixture of two of ethylamine, benzylamine, and naphthylamine. The stabilizer is one or a mixture of methanol, ethanol, propanol, and glycerol. The catalyst is one or a mixture of sodium bisulfate, sodium bisulfite, potassium bisulfate, and potassium bisulfite. The initiator is ammonium persulfate.

[0054] As another example of this embodiment, a laboratory preparation method for the above-mentioned sulfur-dissolving scale inhibitor is provided. Specifically, 6.5 parts of methylene dibutyric acid, 33.5 parts of methylphosphoramide, 9.0 parts of mercaptooleic acid imidazoline, and 4.0 parts of deionized water are placed in a four-necked round-bottom flask. Two constant-pressure separatory funnels are prepared. One funnel contains a mixed solution of 4.5 parts of methacryloyloxyethyltrimethylammonium chloride and 8.0 parts of hydroxyethyl methacrylate, and the other funnel contains 3.0 parts of ammonium persulfate solution. After dilution, the funnels are connected to the four-necked flask. The heating mantle with magnetic stirring function is heated to 80°C. The two constant-pressure separatory funnels are adjusted, and the solution is slowly and alternately added dropwise to the round-bottom flask. After reacting for 2 hours, the solution is allowed to cool to 35°C. The resulting liquid is poured into a pear-shaped separatory funnel and 12.0 parts of ethylamine and benzylamine (in a mass ratio of ethylamine:benzylamine = 1:1) are added. The mixture is shaken 4-5 times and thoroughly stirred with a magnetic stirrer. Add 11.0 parts of ethanol, shake 4-5 times, and stir thoroughly with a magnetic stirrer. Finally, add 3.0 parts of potassium bisulfate, shake 4-5 times, and stir thoroughly with a magnetic stirrer to obtain the sulfur-dissolving scale inhibitor.

[0055] Example 6 As another preferred embodiment of the present invention, this embodiment discloses a highly efficient sulfur-dissolving scale inhibitor, which, by weight, comprises 48 parts of a main agent, 21 parts of a scale inhibitor, 13 parts of a co-solvent, 10 parts of a stabilizer, 4 parts of a catalyst, and 4 parts of an initiator; wherein, the main agent is composed of 34 parts of methylphosphoramide, 9 parts of mercaptooleic acid imidazoline, and 5 parts of water (deionized water can be selected); the scale inhibitor is composed of 9 parts of hydroxyethyl methacrylate, 5 parts of methacryloyloxyethyltrimethylammonium chloride, and 7 parts of methylene succinic acid.

[0056] The aforementioned co-solvent is a primary amine solvent, the stabilizer is an organic alcohol, the catalyst is an acid salt, and the initiator is a compound with a weak bond that readily decomposes into an active species. Specifically, the co-solvent is one or a mixture of two of ethylamine, benzylamine, and naphthylamine. The stabilizer is one or a mixture of methanol, ethanol, propanol, and glycerol. The catalyst is one or a mixture of sodium bisulfate, sodium bisulfite, potassium bisulfate, and potassium bisulfite. The initiator is ammonium persulfate.

[0057] As another example of this embodiment, a laboratory preparation method for the above-mentioned sulfur-dissolving scale inhibitor is provided. Specifically, 7.0 parts of methylene dibutyric acid, 34.0 parts of methylphosphoramide, 9.0 parts of mercaptooleic acid imidazoline, and 5.0 parts of deionized water are placed in a four-necked round-bottom flask. Two constant-pressure separatory funnels are prepared. One funnel contains a mixed solution of 5.0 parts of methacryloyloxyethyltrimethylammonium chloride and 9.0 parts of hydroxyethyl methacrylate, and the other funnel contains 4.0 parts of ammonium persulfate solution. After dilution, the funnels are connected to the four-necked flask. The heating mantle with magnetic stirring function is heated to 80°C. The two constant-pressure separatory funnels are adjusted, and the solution is slowly and alternately added dropwise to the round-bottom flask. After reacting for 2 hours, the solution is allowed to stand and cool to 35°C. The resulting liquid is poured into a pear-shaped separatory funnel and 13.0 parts of ethylamine and benzylamine (in a mass ratio of ethylamine:benzylamine = 1:1) are added. The mixture is shaken 4-5 times and thoroughly stirred with a magnetic stirrer. Add 10.0 parts of ethanol, shake 4-5 times, and stir thoroughly with a magnetic stirrer. Finally, add 4.0 parts of potassium bisulfate, shake 4-5 times, and stir thoroughly with a magnetic stirrer to obtain the sulfur-dissolving scale inhibitor.

[0058] The sulfur-dissolving and scale-inhibiting agents prepared in Examples 1-6 were subjected to sulfur-dissolving and scale-inhibiting performance simulation experiments, respectively. The sulfur-dissolving experiment was carried out at 50°C, and the maximum sulfur dissolution amount of 10g sulfur-dissolving and scale-inhibiting agent in 1 hour was measured.

[0059] The sulfur dissolution test results of the sulfur-dissolving scale inhibitors in Examples 1-6 are shown in Table 1.

[0060] Table 1. Experimental results of maximum sulfur dissolution capacity of 10g sulfur-dissolving scale inhibitor in 1 hour The scale inhibition performance simulation experiment was carried out in accordance with the requirements of SY / T 5673—2020 "General Technical Conditions for Scale Inhibitors for Oilfield Use". The chemical composition and pH value of the experimental simulation solution are shown in Table 2. The scale inhibition experiment was carried out at 50℃. A standard sulfur-dissolving scale inhibitor solution of 100 mg / L was prepared and the static scale inhibition efficiency was determined.

[0061] Table 2 Chemical composition and pH value of the simulated solution in the scale inhibition experiment The scale inhibition performance test results of the sulfur-dissolving scale inhibitors in Examples 1-6 are shown in Table 3.

[0062] Table 3. Experimental results of scale inhibition performance of sulfur-dissolving scale inhibitors The sulfur-dissolving scale inhibitor prepared in Example 6 was used to conduct sulfur dissolution and scale inhibition experiments under different temperature conditions. 10g of the sulfur-dissolving scale inhibitor was used to conduct sulfur dissolution experiments for 1 hour at 40℃, 50℃, 60℃, 70℃, 80℃, and 90℃. A standard sulfur-dissolving scale inhibitor solution of 100mg / L was prepared, and the scale inhibition efficiency was measured at 40℃, 50℃, 60℃, 70℃, 80℃, and 90℃. The experimental results are as follows: Figure 1 As shown in the figure, with the increase of temperature, the amount of sulfur dissolved by the sulfur-dissolving scale inhibitor gradually increases, and the sulfur-dissolving performance gradually improves; at the same time, its scale inhibition performance is relatively stable, and it can maintain a high scale inhibition efficiency at different temperatures.

Claims

1. A highly efficient sulfur-dissolving scale inhibitor, characterized in that: The sulfur-dissolving scale inhibitor comprises the following components by weight: Main agent: 37.5 to 52.5 parts; 15.5 to 23 parts scale inhibitor; 7 to 17.5 parts of co-solvent; Stabilizer 5 to 20 parts; 1 to 5 parts catalyst; Initiator 1 to 5 parts; The main agent is composed of the following components in parts by mass: Methylphosphoramide 27.5 parts to 37.5 parts; 7 to 10 parts of mercaptooleic imidazoline; 3 to 5 parts water; The scale inhibitor is composed of the following components in parts by weight: Hydroxyethyl methacrylate 6.5 to 10 parts; 3.5 to 5.5 parts of methacryloyloxyethyltrimethylammonium chloride; 5.5 to 7.5 parts of methylene succinic acid; The co-solvent is a primary amine solvent, the stabilizer is an organic alcohol, the catalyst is an acid salt, and the initiator is a compound with a weak bond that is easily decomposed into active species.

2. The highly efficient sulfur-dissolving scale inhibitor as described in claim 1, characterized in that: The sulfur-dissolving scale inhibitor comprises the following components by weight: Main agent: 44-49 parts; 17.5 to 21.5 parts scale inhibitor; 9 to 14 parts of co-solvent; Stabilizer: 8 to 15 parts; 2 to 5 parts catalyst; Initiator 2 to 4 parts.

3. The highly efficient sulfur-dissolving scale inhibitor as described in claim 1, characterized in that: The sulfur-dissolving scale inhibitor comprises, by weight, 48 parts of main agent, 21 parts of scale inhibitor, 13 parts of auxiliary solvent, 10 parts of stabilizer, 4 parts of catalyst, and 4 parts of initiator.

4. A highly efficient sulfur-dissolving scale inhibitor as described in any one of claims 1-3, characterized in that: The main agent, by weight, consists of 32.5 to 34.5 parts of methylphosphoramide, 8.5 to 9.5 parts of mercaptooleic imidazoline, and 3 to 5 parts of water.

5. The highly efficient sulfur-dissolving scale inhibitor as described in claim 4, characterized in that: The main agent, by weight, consists of 34 parts methylphosphoramide, 9 parts imidazoline mercaptooleic acid and 5 parts water.

6. A highly efficient sulfur-dissolving scale inhibitor as described in any one of claims 1-3, characterized in that: The scale inhibitor, by weight, consists of 7.5 to 9.5 parts of hydroxyethyl methacrylate, 4 to 5 parts of methacryloyloxyethyltrimethylammonium chloride, and 6 to 7 parts of methylene succinic acid.

7. The highly efficient sulfur-dissolving scale inhibitor as described in claim 6, characterized in that: The scale inhibitor, by weight, consists of 9 parts hydroxyethyl methacrylate, 5 parts methacryloyloxyethyltrimethylammonium chloride, and 7 parts methylene succinic acid.

8. A highly efficient sulfur-dissolving scale inhibitor as described in any one of claims 1-3, characterized in that: The co-solvent is one or a mixture of two of ethylamine, benzylamine, and naphthylamine.

9. A highly efficient sulfur-dissolving scale inhibitor as described in any one of claims 1-3, characterized in that: The stabilizer is one or a mixture of methanol, ethanol, propanol, and glycerol.

10. A highly efficient sulfur-dissolving scale inhibitor as described in any one of claims 1-3, characterized in that: The catalyst is one or a mixture of sodium bisulfate, sodium bisulfite, potassium bisulfate, and potassium bisulfite.

11. A highly efficient sulfur-dissolving scale inhibitor as described in any one of claims 1-3, characterized in that: The initiator is ammonium persulfate.

12. A method for preparing a highly efficient sulfur-dissolving scale inhibitor as described in any one of claims 1-11, characterized in that: The specific steps are as follows: S1. Place methylene dibutyric acid, methylphosphoramide, mercaptooleic acid imidazoline and deionized water into a container; S2. Place the container from step S1 in a heating jacket with a magnetic stirring function and heat it to 80°C. S3. Slowly and alternately add a mixed solution of methacryloyloxyethyltrimethylammonium chloride and hydroxyethyl methacrylate and the initiator to the container from step S2; after the addition is complete, react for 2 hours, and then cool to 35℃~40℃. S4. Add the co-solvent, stabilizer and catalyst sequentially to the container where the reaction in step S3 has been completed. Shake the container 4-5 times after each component is added to ensure thorough mixing before adding the next component. Finally, the sulfur-dissolving scale inhibitor is obtained.

Images