A scale inhibitor for natural gas extraction and its application

Abstract

The present invention discloses a scale inhibitor for natural gas extraction and its application. The scale inhibitor comprises a first main agent, a second main agent, an auxiliary agent, and optionally water. The first main agent comprises polyamide-amine and hydroxyethyl hexahydro-s-triazine, the second main agent is selected from at least one of polyaspartic acid, poly(meth)acrylic acid, and polymaleic acid, and the auxiliary agent comprises bisulfite and alkylphenol polyoxyethylene ether. The scale inhibitor provided by the present invention does not contain phosphorus compounds and can achieve good scale inhibition during natural gas extraction. It also ensures that the groundwater containing the scale inhibitor can be discharged or reinjected after simple treatment, making the natural gas extraction process more environmentally friendly.

Description

Technical Field

[0001] The present invention belongs to the technical field of natural gas extraction, and in particular relates to a scale inhibitor for natural gas extraction and application thereof. Background Art

[0002] Natural gas is an important clean energy source and chemical raw material, playing a crucial role in improving my country's energy structure and building a low-carbon, environmentally friendly society. According to statistics, my country's apparent natural gas consumption in 2020 reached 325.91 billion cubic meters, 22.84 billion cubic meters higher than in 2019, a year-on-year increase of 7.5%. Domestic natural gas production in 2020 reached 188.8 billion cubic meters, meeting 58% of apparent demand, slightly higher than the 57.28% recorded in the same period last year. Net imports reached 129.97 billion cubic meters, a year-on-year increase of 4.3%. Therefore, overall, my country's natural gas consumption increased in 2020, with external dependence at 42%. Natural gas extraction produces mineral water, which contains large amounts of calcium and magnesium carbonates, sulfates, and other metal salts. When local mine water is still deep in the formation, it is difficult to form scale due to its high solubility due to high temperature and high pressure. However, when the local mine water is brought out of the wellbore with natural gas extraction, it will form scale and precipitate due to the decrease in temperature and pressure, and attach to the surface of facilities and equipment such as the well wall, pipelines, valves, etc., or clog valves, affecting normal operations.

[0003] Currently, the scale inhibitors used in natural gas extraction processes are primarily chemical scale inhibitors based on organic or inorganic phosphorus. While these inhibitors are effective, they require further treatment to ensure that the phosphorus compounds meet standards before discharge. This process is complex and costly. Consequently, the use of phosphorus-containing scale inhibitors can significantly increase the cost of natural gas extraction. Summary of the Invention

[0004] In response to the problems existing in the prior art, the purpose of the present invention is to provide a scale inhibitor that does not contain phosphorus compounds, which can not only achieve good scale inhibition effect during the natural gas extraction process, but also ensure that the mineral water containing the scale inhibitor can be discharged or reinjected after simple treatment, making the natural gas extraction process more green and environmentally friendly.

[0005] To this end, the first aspect of the present invention provides a scale inhibitor for natural gas extraction, which includes a main agent 1, a main agent 2, an auxiliary agent and optional water, wherein the main agent 1 includes polyamide-amine and hydroxyethyl hexahydro-s-triazine, the main agent 2 is selected from at least one of polyaspartic acid, poly(meth)acrylic acid and polymaleic acid, and the auxiliary agent includes bisulfite and alkylphenol polyoxyethylene ether.

[0006] According to some embodiments of the present invention, based on the total mass of the scale inhibitor, the mass fraction of the main agent 1 in the scale inhibitor is 10 wt%-25 wt%.

[0007] According to some embodiments of the present invention, based on the total mass of the scale inhibitor, the mass fraction of the second main agent in the scale inhibitor is 10 wt%-25 wt%.

[0008] According to some embodiments of the present invention, based on the total mass of the scale inhibitor, the mass fraction of the auxiliary agent in the scale inhibitor is 2 wt%-5 wt%.

[0009] According to some embodiments of the present invention, based on the total mass of the scale inhibitor, the scale inhibitor comprises 10wt%-25wt% of main agent 1, 10wt%-25wt% of main agent 2, 2wt%-5wt% of auxiliary agent, and the rest is water.

[0010] According to some embodiments of the present invention, the content of the bisulfite in the scale inhibitor is 1 g / L-10 g / L, based on the total volume of the scale inhibitor.

[0011] According to some embodiments of the present invention, the bisulfite is sodium bisulfite and / or potassium bisulfite. In actual use, the content of sodium bisulfite and / or potassium bisulfite is appropriately increased according to the oxygen content of the system.

[0012] According to some embodiments of the present invention, the mass ratio of the polyamidoamine to hydroxyethylhexahydro-s-triazine is (3:1)-(9:1).

[0013] According to some embodiments of the present invention, based on the total mass of the scale inhibitor, the mass fraction of alkylphenol polyoxyethylene ether OP-10 in the scale inhibitor is 2 wt%-4 wt%, and in some embodiments, 2.5 wt%-3 wt%.

[0014] According to some embodiments of the present invention, the polyamidoamine is a dendrimer polyamidoamine PAMAM, which is at least one of 2nd to 6th generation polymers with ethylenediamine as the core.

[0015] According to some embodiments of the present invention, the alkylphenol polyoxyethylene ether is alkylphenol polyoxyethylene ether OP-10.

[0016] According to some embodiments of the present invention, the weight average molecular weight of the polyaspartic acid is 2000-6000, preferably 3000-5000.

[0017] According to some embodiments of the present invention, the weight average molecular weight of the poly(meth)acrylic acid is 2000-6000, preferably 3000-5000.

[0018] According to the present invention, the poly(meth)acrylic acid refers to polyacrylic acid or polymethacrylic acid.

[0019] According to some embodiments of the present invention, the weight average molecular weight of the polymaleic acid is 500-4000, preferably 1000-3500.

[0020] According to the present invention, the scale inhibitor is obtained by mixing a main agent 1, a main agent 2, an auxiliary agent, and optionally water. The order of addition and mixing method are not particularly specified, and common mixing methods can be used to ensure uniform mixing of the components. In some preferred embodiments, the auxiliary agent and water are first mixed uniformly at room temperature or a temperature above room temperature, and then the main agent 1 is added and stirred for at least 30 minutes. Then, the main agent 2 is added and stirred for at least 30 minutes to obtain the scale inhibitor.

[0021] The second aspect of the present invention provides a use of the scale inhibitor provided in the first aspect of the present invention in natural gas production.

[0022] According to some preferred embodiments of the present invention, the scale inhibitor is directly injected into the mining fluid in the application, wherein the mining fluid is selected from at least one of mining water, desulfurization solution, decarbonization solution and desulfurization and decarbonization solution.

[0023] According to some preferred embodiments of the present invention, the scale inhibitor is used at a temperature of not less than 35°C, preferably 35°C-90°C, and in some embodiments 40-60°C.

[0024] According to some preferred embodiments of the present invention, the amount of the scale inhibitor used in the application is 0.5 wt%-2 wt% per unit mass of the mineral fluid.

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] (1) The scale inhibitor of the present invention can significantly enhance the solubility of calcium and magnesium ions in groundwater, inhibiting their scaling and precipitation that may block valves, pipes, and equipment, thereby achieving a good scale inhibition effect.

[0027] (2) The scale inhibitor of the present invention does not contain phosphorus compounds. After use, the wastewater containing the scale inhibitor only needs simple biochemical treatment before being discharged or reinjected, which is more environmentally friendly. DETAILED DESCRIPTION

[0028] To make the present invention easier to understand, the present invention will be described in detail below with reference to the examples. These examples are intended only to illustrate the present invention and should not be construed as limiting the scope of the present invention. Where specific conditions are not specified in the examples, conventional conditions or conditions recommended by the manufacturer are used. The raw materials or reagents used in the examples are all commercially available or obtained by conventional or methods known in the art.

[0029] The data in the examples were obtained using the following test methods:

[0030] Scale inhibition rate test: Determined according to the petroleum and natural gas industry standard SY / T 5673-93 "Performance Evaluation Method of Scale Inhibitors for Oilfields".

[0031] Example 1

[0032] Scale inhibitor composition: Based on the total mass of the scale inhibitor, it consists of the following components in the following mass fractions: 12% polyamidoamine, 3% hydroxyethyl hexahydrotriazine, 15% polyaspartic acid, 2.5% alkylphenol polyoxyethylene ether OP-10, and 3.5g / L sodium bisulfite. The remainder is water. The polyamidoamine used is a dendrimer polymer, polyamidoamine (PAMAM), a fourth-generation polymer with ethylenediamine as its core. The weight-average molecular weight of the polyaspartic acid used is 3000-5000.

[0033] Preparation method: Alkylphenol polyoxyethylene ether OP-10 and sodium bisulfite were first mixed with water, followed by the addition of polyamide-amine and hydroxyethyl hexahydro-s-triazine, and stirring for 30 minutes. Polyaspartic acid was then added and stirred for 30 minutes to obtain a scale inhibitor. The scale inhibition rate of the obtained scale inhibitor was determined. During the determination, the scale inhibitor was used at a dosage of 1.0% per unit mass of mineral water and the operating temperature of the scale inhibitor was 50°C. The results are shown in Table 1.

[0034] Example 2

[0035] The scale inhibitor composition, based on total mass, consists of 12% polyamidoamine, 3% hydroxyethyl hexahydrotriazine, 17% polyacrylic acid, 2.5% alkylphenol polyoxyethylene ether OP-10, and 3.5g / L sodium bisulfite, with the remainder being water. The polyamidoamine used is a dendrimer, polyamidoamine (PAMAM), a fourth-generation polymer with ethylenediamine as its core. The polyacrylic acid has a weight-average molecular weight of 3,000-5,000.

[0036] Preparation method: Alkylphenol polyoxyethylene ether OP-10 and sodium bisulfite were first mixed with water, followed by the addition of polyamide-amine and hydroxyethyl hexahydro-s-triazine, and stirring for 30 minutes. Polyacrylic acid was then added and stirred for 30 minutes to obtain a scale inhibitor. The scale inhibition rate of the obtained scale inhibitor was determined. During the determination, the scale inhibitor was used at a dosage of 1.0% per unit mass of mineral water and the operating temperature was 50°C. The results are shown in Table 1.

[0037] Example 3

[0038] The scale inhibitor composition, based on total mass, consists of 12% polyamidoamine, 3% hydroxyethyl hexahydrotriazine, 16% polymaleic acid, 3.0% alkylphenol polyoxyethylene ether OP-10, and 3.5g / L sodium bisulfite, with the remainder being water. The polyamidoamine used is a dendrimer, polyamidoamine (PAMAM), a fourth-generation polymer with ethylenediamine as its core. The polymaleic acid has a weight-average molecular weight of 1000-3500.

[0039] Preparation method: Alkylphenol polyoxyethylene ether OP-10 and sodium bisulfite were first mixed with water, followed by the addition of polyamide-amine and hydroxyethyl hexahydro-s-triazine, and stirring for 30 minutes. Polymaleic acid was then added and stirred for 30 minutes until uniformly mixed to obtain a scale inhibitor. The scale inhibition rate of the obtained scale inhibitor was determined. During the determination, the scale inhibitor was used at a dosage of 1.0% per unit mass of mineral water, and the operating temperature of the scale inhibitor was 50°C. The results are shown in Table 1.

[0040] Example 4

[0041] The scale inhibitor composition, based on the total mass of the scale inhibitor, includes 18% polyamidoamine, 3% hydroxyethyl hexahydrotriazine, 10% polyaspartic acid, 10% polyacrylic acid, 3.0% alkylphenol polyoxyethylene ether OP-10, and 3.5 g / L sodium bisulfite. The remainder is water. The polyamidoamine used is a dendrimer polymer, polyamidoamine (PAMAM), a fifth-generation polymer with ethylenediamine as its core. The polyaspartic acid used is the same as in Example 1, and the polyacrylic acid used is the same as in Example 2.

[0042] Preparation method: Alkylphenol polyoxyethylene ether OP-10 and sodium bisulfite were first mixed with water, followed by the addition of polyamide-amine and hydroxyethyl hexahydro-s-triazine, and stirring for 30 minutes. Polyaspartic acid and polyacrylic acid were then added and stirred for 30 minutes to obtain a scale inhibitor. The scale inhibition rate of the obtained scale inhibitor was determined. During the determination, the scale inhibitor was used at a dosage of 1.0% per unit mass of mineral water, and the operating temperature of the scale inhibitor was 50°C. The results are shown in Table 1.

[0043] Example 5

[0044] The scale inhibitor composition, based on the total mass of the scale inhibitor, includes 24% polyamidoamine, 3% hydroxyethyl hexahydro-s-triazine, 10% polyaspartic acid, 10% polymaleic acid, 3.0% alkylphenol polyoxyethylene ether OP-10, and 3.5 g / L sodium bisulfite, with the remainder being water. The polyamidoamine used is a dendrimer polymer, polyamidoamine (PAMAM), a fifth-generation polymer with ethylenediamine as its core. The polyaspartic acid used is the same as in Example 1, and the polymaleic acid used is the same as in Example 3.

[0045] Preparation method: Alkylphenol polyoxyethylene ether OP-10 and sodium bisulfite were first mixed with water, followed by the addition of polyamide-amine and hydroxyethyl hexahydro-s-triazine, and stirring for 30 minutes. Polyaspartic acid and polymaleic acid were then added and stirred for 30 minutes to obtain a scale inhibitor. The scale inhibition rate of the obtained scale inhibitor was determined. The scale inhibitor was used at a dosage of 1.0% per unit mass of mineral water and a temperature of 50°C. The results are shown in Table 1.

[0046] Example 6

[0047] The scale inhibitor composition, based on the total mass of the scale inhibitor, includes 10% polyamidoamine, 5% hydroxyethyl hexahydro-s-triazine, 15% polyaspartic acid, 2.5% alkylphenol polyoxyethylene ether OP-10, and 3.5 g / L sodium bisulfite, with the remainder being water. The polyamidoamine used is a dendrimer polymer, polyamidoamine (PAMAM), a fourth-generation polymer with ethylenediamine as its core. The polyaspartic acid used is the same as in Example 1.

[0048] Preparation method: Alkylphenol polyoxyethylene ether OP-10 and sodium bisulfite were first mixed with water, followed by the addition of polyamide-amine and hydroxyethyl hexahydro-s-triazine, and stirring for 30 minutes. Polyaspartic acid was then added and stirred for 30 minutes to obtain a scale inhibitor. The scale inhibition rate of the obtained scale inhibitor was determined. During the determination, the scale inhibitor was used at a dosage of 1.0% per unit mass of mineral water and the operating temperature of the scale inhibitor was 50°C. The results are shown in Table 1.

[0049] Example 7

[0050] The scale inhibitor composition, based on the total mass of the scale inhibitor, includes 13% polyamidoamine, 2% hydroxyethyl hexahydro-s-triazine, 15% polyaspartic acid, 2.5% alkylphenol polyoxyethylene ether OP-10, and 3.5 g / L sodium bisulfite, with the remainder being water. The polyamidoamine used is a dendrimer polymer, polyamidoamine (PAMAM), a fourth-generation polymer with ethylenediamine as its core. The polyaspartic acid used is the same as that used in Example 1.

[0051] Preparation method: Alkylphenol polyoxyethylene ether OP-10 and sodium bisulfite were first mixed with water, followed by the addition of polyamide-amine and hydroxyethyl hexahydro-s-triazine, and stirring for 30 minutes. Polyaspartic acid was then added and stirred for 30 minutes to obtain a scale inhibitor. The scale inhibition rate of the obtained scale inhibitor was determined. During the determination, the scale inhibitor was used at a dosage of 1.0% per unit mass of mineral water and the operating temperature of the scale inhibitor was 50°C. The results are shown in Table 1.

[0052] Comparative Example 1

[0053] Scale inhibitor composition: based on the total mass of the scale inhibitor, it contains 15% polyamide-amine, 15% polyaspartic acid, 3% alkylphenol polyoxyethylene ether OP-10 and 3.5g / L sodium bisulfite, and the rest is water. Among them, the polyamide-amine used is a dendritic polymer polyamide amine PAMAM, which is a fourth-generation polymer with ethylenediamine as the core, and the polyaspartic acid used is the same as in Example 1. Preparation method: First, alkylphenol polyoxyethylene ether OP-10 and sodium bisulfite are mixed with water, and then polyamide-amine is added and stirred for 30 minutes, and then polyaspartic acid is added and stirred for 30 minutes to mix evenly to obtain a scale inhibitor and measure the scale inhibition rate of the obtained scale inhibitor. During the measurement, the amount of scale inhibitor used is 1.0% of the unit mass of mineral water, and the operating temperature of the scale inhibitor is 50°C. The results are shown in Table 1.

[0054] Comparative Example 2

[0055] The scale inhibitor composition, based on the total mass of the scale inhibitor, includes 15% hydroxyethyl hexahydro-s-triazine, 15% polyaspartic acid, 3% alkylphenol polyoxyethylene ether OP-10, and 3.5 g / L sodium bisulfite, with the remainder being water. The polyamidoamine used is a dendrimer polymer, polyamidoamine (PAMAM), a fourth-generation polymer with ethylenediamine as its core. The polyaspartic acid used is the same as in Example 1.

[0056] Preparation method: Alkylphenol polyoxyethylene ether OP-10 and sodium bisulfite were first mixed with water, and then hydroxyethyl hexahydro-s-triazine was added and stirred for 30 minutes. Polyaspartic acid was then added and stirred for 30 minutes to mix evenly to obtain a scale inhibitor. The scale inhibition rate of the obtained scale inhibitor was measured. During the measurement, the scale inhibitor was used at a dosage of 1.0% per unit mass of mineral water and the operating temperature of the scale inhibitor was 50°C. The results are shown in Table 1.

[0057] Comparative Example 3

[0058] The scale inhibitor composition, based on the total mass of the scale inhibitor, includes 15% polyaspartic acid, 2.5% alkylphenol polyoxyethylene ether OP-10, and 3.5 g / L sodium bisulfite, with the remainder being water. The polyamidoamine used is a dendrimer polyamidoamine (PAMAM), a fourth-generation polymer with ethylenediamine as its core. The polyaspartic acid used is the same as in Example 1.

[0059] Preparation method: Alkylphenol polyoxyethylene ether OP-10 and sodium bisulfite were first mixed with water, and then polyaspartic acid was added. The mixture was stirred for 30 minutes until uniform, thereby obtaining a scale inhibitor. The scale inhibition rate of the obtained scale inhibitor was determined. During the determination, the scale inhibitor was used at a dosage of 1.0% per unit mass of mineral water and the operating temperature of the scale inhibitor was 50°C. The results are shown in Table 1.

[0060] Comparative Example 4

[0061] The scale inhibitor composition is as follows: based on the total mass of the scale inhibitor, it comprises 15% polyacrylic acid, 10% polymaleic acid, 2.5% alkylphenol polyoxyethylene ether OP-10 and 3.5 g / L sodium bisulfite, and the rest is water.

[0062] Preparation method: Alkylphenol polyoxyethylene ether OP-10 and sodium bisulfite were first mixed with water, and then polyacrylic acid and polymaleic acid were added. The mixture was stirred for 30 minutes until uniform. The scale inhibitor was obtained and its scale inhibition rate was measured. The amount of the scale inhibitor used was 1.0% per unit mass of the mineral water, and the operating temperature of the scale inhibitor was 50°C. The results are shown in Table 1.

[0063] Table 1

[0064]

[0065] From the results in Table 1, it can be seen that the scale inhibitor proposed in the present invention has a high scale inhibition rate, can delay the scaling of valves, pipes and equipment for a long time, and reduce production costs. At the same time, the scale inhibitor proposed in this application does not contain phosphorus compounds, and only needs simple biochemical treatment to be discharged or reinjected during wastewater treatment.

[0066] It should be noted that the embodiments described above are only used to explain the present invention and do not constitute any limitation of the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words, rather than restrictive words. The present invention may be modified as specified within the scope of the claims of the present invention, and the present invention may be revised without departing from the scope and spirit of the present invention. Although the present invention described therein relates to specific methods, materials and embodiments, it does not mean that the present invention is limited to the specific examples disclosed therein. On the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. A scale inhibitor for natural gas production, comprising a main agent (I), a main agent (II), an auxiliary agent, and optionally water, wherein the main agent (I) comprises polyamide-amine and hydroxyethyl hexahydro-s-triazine, the main agent (II) is selected from at least two of polyaspartic acid, polyacrylic acid, and polymaleic acid, and the auxiliary agent comprises bisulfite and alkylphenol polyoxyethylene ether; and in the main agent (I), the mass ratio of the polyamide-amine to the hydroxyethyl hexahydro-s-triazine is (3:1)-(9:1).

2. The scale inhibitor according to claim 1, characterized in that Based on the total mass of the scale inhibitor, the mass fraction of the main agent 1 in the scale inhibitor is 10 wt%-25 wt%, and / or the mass fraction of the main agent 2 in the scale inhibitor is 10 wt%-25 wt%, and / or the mass fraction of the auxiliary agent in the scale inhibitor is 2 wt%-5 wt%.

3. The scale inhibitor according to claim 1 or 2, characterized in that Based on the total mass of the scale inhibitor, the scale inhibitor comprises 10 wt%-25 wt% of the main agent 1, 10 wt%-25 wt% of the main agent 2, 2 wt%-5 wt% of the auxiliary agent, and the rest is water.

4. The scale inhibitor according to claim 1 or 2, characterized in that Based on the total volume of the scale inhibitor, the content of the bisulfite in the scale inhibitor is 1 g / L-10 g / L.

5. The scale inhibitor according to claim 1 or 2, characterized in that The polyamidoamine is a dendrimer polyamidoamine PAMAM, which is at least one of the 2nd to 6th generation polymers with ammonia and / or ethylenediamine as the core; and / or the bisulfite is sodium bisulfite and / or potassium bisulfite; And / or the alkylphenol polyoxyethylene ether is alkylphenol polyoxyethylene ether OP-10.

6. The scale inhibitor according to claim 1 or 2, characterized in that The weight average molecular weight of the polyaspartic acid is 2000-6000; and / or the weight average molecular weight of the polyacrylic acid is 2000-6000; And / or the weight average molecular weight of the polymaleic acid is 500-4000.

7. The scale inhibitor according to claim 6, characterized in that The weight average molecular weight of the polyaspartic acid is 3000-5000; and / or the weight average molecular weight of the polyacrylic acid is 3000-5000; And / or the weight average molecular weight of the polymaleic acid is 1000-3500.

8. Use of the scale inhibitor according to any one of claims 1 to 7 in natural gas production.

9. The use according to claim 8, characterized in that The scale inhibitor is directly injected into the mining liquid, and the mining liquid is selected from at least one of mining water, desulfurization solution, decarbonization solution and desulfurization and decarbonization solution.

10. The use according to claim 8 or 9, characterized in that In the application, the temperature of the antiscalant during use is not lower than 35°C.

11. The use according to claim 10, characterized in that In the application, the antiscalant is used at a temperature of 35°C-90°C.

12. The use according to claim 8 or 9, characterized in that The amount of the scale inhibitor used in the application is 0.5wt%-2wt% per unit mass of the mineral fluid.

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