Oil field acidification and fracturing ferric ion stabilizer, and preparation method and application thereof

Abstract

This invention belongs to the field of fracturing and acidizing technology, specifically relating to an iron ion stabilizer for oilfield acidizing fracturing, its preparation method, and its application. The oilfield acidizing fracturing iron ion stabilizer, by weight percentage, is composed of the following raw materials: 5-10% iron ion stabilizer main agent, 1-2% iron ion stabilizer auxiliary agent, and the balance being a mixed solvent; the structural formula of the iron ion stabilizer main agent is as follows; the iron ion stabilizer auxiliary agent is one or more of ascorbic acid, isoascorbic acid, and glucose; the mixed solvent is a mixture of methanol and water in a volume ratio of 1:1. The iron ion stabilizer of this invention has the advantages of good iron ion stabilization effect and good temperature resistance; it also has low interfacial tension and drainage-aiding functions.

Description

Technical Field

[0001] This invention belongs to the field of fracturing and acidizing technology, specifically relating to an iron ion stabilizer for oilfield acidizing and fracturing, its preparation method, and its application. Background Technology

[0002] In the field of oil and gas field development, acid fracturing technology is one of the core measures to improve reservoir permeability and achieve stable and increased oil and gas well production. This technology restores and improves fluid permeability by injecting acid into the formation to dissolve blockages in the pores or fractures of the reservoir rock. However, a long-standing and serious technical problem during acidizing operations is the secondary precipitation damage caused by iron ions. Throughout the process from wellhead injection to reaction with the formation rock, the acid comes into contact with metal equipment such as the drilling tubing and downhole tools, corroding and generating iron ions. At the same time, after entering the reservoir, the acid also dissolves iron-bearing minerals in the formation, resulting in a large amount of Fe²⁺ and Fe³⁺ entering the acid system. As the acid-rock reaction continues, the effective concentration of the acid is gradually consumed, the pH value continues to rise, and the Fe³⁺ in the solution is easily hydrolyzed to form a gel-like ferric hydroxide precipitate.

[0003] These ferric hydroxide precipitates are extremely damaging to oil and gas reservoirs. They clog newly opened or recently cleared formation pores and channels, causing a further decrease in permeability and severely weakening the effectiveness of acidizing treatment. Furthermore, the presence of iron ions enhances the stability of residual acid emulsions, increases the difficulty of flowback, and may exacerbate the formation of asphaltenes, causing complex secondary pollution to the reservoir. For a long time, how to effectively control iron ion precipitation has been a focus of attention in the field of acid fracturing technology.

[0004] To prevent the formation of iron precipitates when the acid solution becomes residual acid, iron ion stabilizers are often added to the acid solution in acidification technology. This prevents the formation of gel-like iron hydroxide precipitates when the acid solution becomes residual acid, thus preventing damage to the oil and gas reservoir and improving the acidification effect.

[0005] Invention patent CN104109530A discloses an iron ion stabilizer for acidification and its preparation method. This iron ion stabilizer consists of the following components in parts by weight: 2-3 parts chelating agent, 1-2 parts reducing agent, and 1-2 parts pH buffer. This iron ion stabilizer for acidification mainly consists of a chelating agent, a reducing agent, and a pH buffer. The chelating agent, reducing agent, and pH buffer work synergistically, providing both chelating and reducing capabilities to maximize the stabilization of iron ions during acidification. Simultaneously, the small amount of each component reduces acidification costs, and the low amount of metal ions added to the formula does not cause additional damage to the reservoir. The low production and usage costs make it suitable for widespread application. However, the iron ion stabilization capacity of this stabilizer is only about 10 mg / ml, which is poor and cannot meet production requirements.

[0006] Invention patent CN105295887 A discloses a high-performance iron ion stabilizer for acidification operations and its preparation method. The technical solution involves adding sodium isoascorbate, NTA, citric acid, disodium EDTA, and water to a container in the following proportions: sodium isoascorbate 5%–16%, NTA 1%–3%, citric acid 2%–5%, disodium EDTA 2%–5%, with the remainder being water. The mixture is stirred at a controlled temperature until completely dissolved, cooled to room temperature, transferred to a volumetric flask, and diluted to volume to obtain the iron ion stabilizer. This iron ion stabilizer possesses both chelating and reducing abilities, exhibits strong iron ion stabilization capacity, and has low production costs. However, at 80℃, the iron ion stabilization capacity decreases to 30 mg / ml, making it difficult to meet practical production needs. This invention provides an iron ion stabilizer for oilfield acid fracturing, its preparation method, and its application. The iron ion stabilizer of this invention has the advantages of good iron ion stabilization effect and good temperature resistance; it also has low interfacial tension and drainage-aiding functions.

[0007] The first objective of this invention discloses an iron ion stabilizer for oilfield acid fracturing, wherein the iron ion stabilizer for oilfield acid fracturing is composed of the following raw materials by weight percentage: Iron ion stabilizer main component 5-10%; Iron ion stabilizer adjuvant 1-2%; Mixed solvent balance; The structural formula of the iron ion stabilizer is as follows: .

[0008] The iron ion stabilizer adjuvant is one or more of ascorbic acid, isoascorbic acid, and glucose.

[0009] The mixed solvent is a mixture of methanol and water in a volume ratio of 1:1.

[0010] The second objective of this invention is to provide a method for preparing the aforementioned iron ion stabilizer, the method specifically comprising the following steps: S1. Add cyanuric chloride and methanol / water mixed solvent to the first reactor. The volume ratio of methanol to water is 1:1. Stir and cool down to 5°C or below. Add 12-aminododecanoic acid in batches. While stirring, add sodium hydroxide solution dropwise to maintain pH 7-8. After the addition is complete, continue the reaction for 0.5 hours or more. The temperature is controlled not to exceed 10°C throughout the process. S2. Continue to add iminodiacetic acid in batches, while stirring and adding sodium hydroxide solution dropwise to maintain pH 7-8. After the addition is complete, continue the reaction for 0.5 hours or more. The temperature should not exceed 40℃ throughout the process. S3. Continue to slowly add tetraethylenepentamine while stirring and adding sodium hydroxide solution to maintain pH 7-8. Control the temperature at 60-80℃ throughout the process and continue the reaction for 2 hours or more. S4. Remove some solvent by vacuum distillation, cool to crystallize, filter, and dry to obtain the iron ion stabilizer main agent; S5. Add the mixed solvent, iron ion stabilizer main agent, and iron ion stabilizer auxiliary agent to the second reactor in sequence, and stir evenly to obtain the acid fracturing iron ion stabilizer.

[0011] In this invention, the molar ratio of 12-aminododecanoic acid, iminodiacetic acid, tetraethylenepentamine, and cyanuric chloride is further 0.8-1.2:0.8-1.2:0.8-1.2:1; even further, the molar ratio of 12-aminododecanoic acid, iminodiacetic acid, tetraethylenepentamine, and cyanuric chloride is 0.9-1.1:0.9-1.1:0.9-1.1:1.

[0012] Furthermore, the mass ratio of the methanol / water mixed solvent to cyanuric chloride in step S1 is 12-15:1.

[0013] A third objective of this invention is to provide the application of the aforementioned iron ion stabilizer in oilfield acid fracturing.

[0014] The iron ion stabilizer for oilfield acid fracturing of this invention consists of a main iron ion stabilizer and an auxiliary iron ion stabilizer. The main iron ion stabilizer contains a large number of carboxylic acid functional groups, exhibiting strong chelating effects that significantly reduce free iron ions, thereby reducing the likelihood of iron ions precipitating from the solution. The dodecyl acid in the main stabilizer, being a long-chain carboxylic acid, can chelate iron ions over a wide spatial range. The molecule also contains numerous primary, secondary, and tertiary amine functional groups, and the nitrogen element contains lone pairs of electrons, which can form coordinate bonds with iron ions, further reducing free iron ions. The auxiliary iron ion stabilizer contains a large number of hydroxyl groups and oxygen atoms. The lone pairs of electrons in the oxygen atoms can coordinate with the empty orbitals of iron ions, reducing free iron ions. The auxiliary stabilizer also has reducing properties, reducing ferric iron to ferrous iron, making iron atoms less prone to precipitation in a higher pH range.

[0015] Compared with the prior art, the present invention has the following advantages and beneficial effects: The iron ion stabilizer of this invention has a strong ability to stabilize iron ions, up to 155 mg / g. The iron ion stabilizer of this invention has strong temperature resistance, and its ability to stabilize iron ions at 120℃ can reach up to 150 mg / g. The iron ion stabilizer of this invention has certain interfacial activity, and the interfacial tension can be as low as 3.2 mN / m. Attached Figure Description

[0016] Appendix Figure 1 The infrared spectrum of Z5, the main iron ion stabilizer of this invention. Detailed Implementation

[0017] The technical solution of the present invention will be further described below with reference to specific embodiments: Example 1: Preparation of iron ion stabilizer main agent Z1 S1. Add 0.05 mol cyanuric chloride and 111 g methanol / water mixed solvent (V:V=1:1) to the reactor, stir and cool to 2℃, add 0.04 mol 12-aminododecanoic acid in batches, add sodium hydroxide solution dropwise while stirring, maintain pH 7-8, continue reaction for 1 h after the addition is complete, and control the temperature at 8℃ throughout the process. S2. Continue to add 0.06 mol iminodiacetic acid in batches, while stirring and adding sodium hydroxide solution dropwise to maintain pH 7-8. After the addition is complete, continue the reaction for 1 hour. The temperature should not exceed 35℃ throughout the process. S3. Continue to slowly add 0.04 mol tetraethylenepentamine, while stirring and adding sodium hydroxide solution dropwise to maintain pH 7-8. The temperature is controlled at 70℃ throughout the process, and the reaction continues for 2 hours. S4. Remove some of the solvent by vacuum distillation, cool to crystallize, filter, and dry to obtain the iron ion stabilizer main agent Z1.

[0018] Example 2 Preparation of iron ion stabilizer main agent Z2 S1. Add 0.05 mol cyanuric chloride and 138 g methanol / water mixed solvent (V:V=1:1) to the reactor, stir and cool to 5℃, add 0.06 mol 12-aminododecanoic acid in batches, add sodium hydroxide solution dropwise while stirring, maintain pH 7-8, continue reaction for 0.5 h after the addition is complete, and control the temperature at 10℃ throughout the process. S2. Continue to add 0.04 mol iminodiacetic acid in batches, while stirring and adding sodium hydroxide solution dropwise to maintain pH 7-8. After the addition is complete, continue the reaction for 0.5 h. The temperature should not exceed 40℃ throughout the process. S3. Continue to slowly add 0.06 mol of tetraethylenepentamine, while stirring and adding sodium hydroxide solution dropwise to maintain pH 7-8. The temperature is controlled at 80℃ throughout the process, and the reaction continues for 2.5 hours. S4. Remove some of the solvent by vacuum distillation, cool to crystallize, filter, and dry to obtain the iron ion stabilizer main agent Z2.

[0019] Example 3 Preparation of iron ion stabilizer main agent Z3 S1. Add 0.05 mol cyanuric chloride and 123 g methanol / water mixed solvent (V:V=1:1) to the reactor, stir and cool to 2℃, add 0.045 mol 12-aminododecanoic acid in batches, add sodium hydroxide solution dropwise while stirring, maintain pH 7-8, continue reaction for 1.2 h after the addition is complete, and control the temperature at 8℃ throughout the process. S2. Continue to add 0.055 mol iminodiacetic acid in batches, while stirring and adding sodium hydroxide solution dropwise to maintain pH 7-8. After the addition is complete, continue the reaction for 0.6 h. The temperature should not exceed 30℃ throughout the process. S3. Continue to slowly add 0.045 mol tetraethylenepentamine, while stirring and adding sodium hydroxide solution dropwise to maintain pH 7-8. The temperature is controlled at 60℃ throughout the process, and the reaction continues for 2.5 h. S4. Remove some of the solvent by vacuum distillation, cool to crystallize, filter, and dry to obtain the iron ion stabilizer main agent Z3.

[0020] Example 4 Preparation of iron ion stabilizer Z4 S1. Add 0.05 mol cyanuric chloride and 121 g methanol / water mixed solvent (V:V=1:1) to the reactor, stir and cool to 0℃, add 0.055 mol 12-aminododecanoic acid in batches, add sodium hydroxide solution dropwise while stirring, maintain pH 7-8, continue reaction for 0.6 h after the addition is complete, and control the temperature at 8℃ throughout the process. S2. Continue to add 0.045 mol iminodiacetic acid in batches, while stirring and adding sodium hydroxide solution dropwise to maintain pH 7-8. After the addition is complete, continue the reaction for 0.8 h. The temperature should not exceed 30℃ throughout the process. S3. Continue to slowly add 0.055 mol tetraethylenepentamine, while stirring and adding sodium hydroxide solution dropwise to maintain pH 7-8. The temperature is controlled at 70℃ throughout the process, and the reaction continues for 3 hours. S4. Remove some of the solvent by vacuum distillation, cool to crystallize, filter, and dry to obtain the iron ion stabilizer main agent Z4.

[0021] Example 5 Preparation of iron ion stabilizer main agent Z5 S1. Add 0.05 mol cyanuric chloride and 130 g methanol / water mixed solvent (V:V=1:1) to the reactor, stir and cool to 3℃, add 0.05 mol 12-aminododecanoic acid in batches, add sodium hydroxide solution dropwise while stirring, maintain pH 7-8, continue reaction for 0.8 h after the addition is complete, and control the temperature at 6℃ throughout the process. S2. Continue to add 0.05 mol iminodiacetic acid in batches, while stirring and adding sodium hydroxide solution dropwise to maintain pH 7-8. After the addition is complete, continue the reaction for 1.2 h. The temperature should not exceed 35℃ throughout the process. S3. Continue to slowly add 0.05 mol tetraethylenepentamine, while stirring and adding sodium hydroxide solution dropwise to maintain pH 7-8. The temperature is controlled at 75℃ throughout the process, and the reaction continues for 3 hours. S4. Remove some of the solvent by vacuum distillation, cool to crystallize, filter, and dry to obtain the iron ion stabilizer main agent Z5.

[0022] Example 6 Preparation of iron ion stabilizer 94g of methanol / water mixed solvent (V:V=1:1), 5g of Z1, and 1g of ascorbic acid were added sequentially to the reactor and stirred until homogeneous to obtain an acid fracturing iron ion stabilizer.

[0023] Example 7 Preparation of iron ion stabilizer 91.5g of methanol / water mixed solvent (V:V=1:1), 7g of Z2, and 1.5g of isoascorbic acid were added sequentially to the reactor and stirred until homogeneous to obtain an acid fracturing iron ion stabilizer.

[0024] Example 8 Preparation of iron ion stabilizer 90.5g of methanol / water mixed solvent (V:V=1:1), 8g of Z3, and 1.5g of glucose were added sequentially to the reactor and stirred until homogeneous to obtain an acid fracturing iron ion stabilizer.

[0025] Example 9 Preparation of iron ion stabilizer 89g of methanol / water mixed solvent (V:V=1:1), 9g of Z4, and 2g of ascorbic acid were added sequentially to the reactor and stirred until homogeneous to obtain an acid fracturing iron ion stabilizer.

[0026] Example 10 Preparation of iron ion stabilizer 88g of methanol / water mixed solvent (V:V=1:1), 10g of Z5, 1g of ascorbic acid, 0.5g of isoascorbic acid, and 0.5g of glucose were added sequentially to the reactor and stirred until homogeneous to obtain an acid fracturing iron ion stabilizer.

[0027] Comparative Example 1 The preparation method is the same as in Example 6, except that Z1 is not added and the amount of methanol / water mixed solvent (V:V=1:1) added is 99g.

[0028] Comparative Example 2 The preparation method is the same as in Example 6, except that ascorbic acid is not added and the amount of methanol / water mixed solvent (V:V=1:1) added is 95g.

[0029] Comparative Example 3 Kaifeng Hengju Biotechnology Co., Ltd. uses HJZ-801 iron stabilizer for acidification.

[0030] Test Example 1 The iron ion stabilization capabilities W1 and W2 of the iron ion stabilizer of the present invention were tested at room temperature and 120℃. The test method was in accordance with SY / T 6571-2012 "Performance Evaluation Method of Iron Ion Stabilizer for Acidification". The test results are shown in Table 1.

[0031] Test Example 2 The iron ion stabilizer of this invention was diluted 100 times with water, and the interfacial tension was tested. The oil phase used was dehydrated crude oil from an oilfield with a viscosity of 158 mPa∙s. The test results are shown in Table 1.

[0032] Table 1. Test results of iron ion stabilization ability and interfacial tension

[0033] As can be seen from Examples 6-10 and Comparative Example 3, the iron ion stabilizer of the present invention has a significantly higher iron ion stabilizing effect than the comparative example. Data W1 and W2 show that the iron ion stabilizer of the present invention has good temperature resistance; its iron ion stability at 120℃ is close to that at room temperature. Examples 6 and Comparative Examples 1 and 2 show that the iron ion stabilizing ability and interfacial activity of the iron ion stabilizer of the present invention mainly come from the iron ion stabilizer main agent.

[0034] Test Example 3 The iron ion stabilizer Z5 was characterized by infrared spectroscopy, and the results are as follows: Figure 1 As shown.

[0035] Figure 1 Middle, 3436cm - It is the NH bond stretching vibration peak, 1650 cm⁻¹. - yes Bond stretching vibration peak, 1210 cm⁻¹ - yes Bond stretching vibration peak.

[0036] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any form or substance. It should be noted that those skilled in the art can make various improvements and additions without departing from the method of the present invention, and these improvements and additions are also considered to be within the scope of protection of the present invention. Any modifications, alterations, and equivalent changes made by those skilled in the art based on the above-disclosed technical content without departing from the spirit and scope of the present invention are equivalent embodiments of the present invention. Furthermore, any equivalent changes, alterations, and evolutions made to the above embodiments based on the essential technology of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. An oilfield acidizing fracturing iron stabilizer characterized in that, The iron ion stabilizer, by weight percentage, is composed of the following raw materials: Iron ion stabilizer main component 5-10%; Iron ion stabilizer adjuvant 1-2%; Mixed solvent balance; The structural formula of the iron ion stabilizer is as follows: ； The iron ion stabilizer adjuvant is one or more of ascorbic acid, isoascorbic acid, and glucose; The mixed solvent is a mixture of methanol and water in a volume ratio of 1:

1.

2. The method for producing an iron ion stabilizer according to claim 1, wherein The preparation method specifically includes the following steps: S1. Add cyanuric chloride and methanol / water mixed solvent to the first reactor. The volume ratio of methanol to water is 1:

1. Stir and cool down to 5°C or below. Add 12-aminododecanoic acid in batches. While stirring, add sodium hydroxide solution dropwise to maintain pH 7-8. After the addition is complete, continue the reaction for 0.5 hours or more. The temperature is controlled not to exceed 10°C throughout the process. S2. Continue to add iminodiacetic acid in batches, while stirring and adding sodium hydroxide solution dropwise to maintain pH 7-8. After the addition is complete, continue the reaction for 0.5 hours or more. The temperature should not exceed 40℃ throughout the process. S3. Continue to slowly add tetraethylenepentamine while stirring and adding sodium hydroxide solution to maintain pH 7-8. Control the temperature at 60-80℃ throughout the process and continue the reaction for 2 hours or more. S4. Remove some solvent by vacuum distillation, cool to crystallize, filter, and dry to obtain the iron ion stabilizer main agent; S5. Add the mixed solvent, iron ion stabilizer main agent, and iron ion stabilizer auxiliary agent to the second reactor in sequence, and stir evenly to obtain the acid fracturing iron ion stabilizer.

3. The production method according to claim 2, wherein The molar ratio of 12-aminododecanoic acid, iminodiacetic acid, tetraethylenepentamine and cyanuric chloride is 0.8-1.2:0.8-1.2:0.8-1.2:

1.

4. The production method according to claim 3, wherein The molar ratio of 12-aminododecanoic acid, iminodiacetic acid, tetraethylenepentamine and cyanuric chloride is 0.9-1.1:0.9-1.1:0.9-1.1:

1.

5. The production method according to claim 2, wherein The mass ratio of methanol / water mixed solvent to cyanuric chloride in step S1 is 12-15:

1.

6. The application of the iron ion stabilizer as described in claim 1 in oilfield acid fracturing.

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