Efficient blocking remover for oil-water well as well as preparation method and application of efficient blocking remover

Abstract

The invention belongs to the technical field of oil exploitation, and particularly relates to an efficient blocking remover for an oil-water well as well as a preparation method and application thereof. The blocking remover consists of the following raw materials in percentage by weight: 2-4% of an acid blocking remover; 0.1 to 0.2 percent of a multifunctional blocking remover; 0.2%-0.5% of a reinforced blocking remover; and the balance of water. Wherein the acid blocking remover is one or two of hydrochloric acid, hydrofluoric acid and citric acid. The structural formula of the multifunctional blocking remover is shown in the specification. The reinforced blocking remover is one or more of 3-(N, N-dimethyl dodecyl ammonium) propane sulfonate, 3-(N, N-dimethyl tetradecyl ammonium) propane sulfonate, 3-(N, N-dimethyl hexadecyl ammonium) propane sulfonate and 3-(N, N-dimethyl octadecyl ammonium) propane sulfonate. The blocking remover has the advantages of being good in blocking removal effect, low in corrosion rate and free of secondary pollution.

Description

Technical Field

[0001] This invention belongs to the field of petroleum extraction technology, specifically relating to a highly efficient unblocking agent for oil and water wells, its preparation method, and its application. Background Technology

[0002] In the process of oil and gas extraction, near-wellbore blockage is a core problem restricting the efficient development and stable production of oilfields. It persists throughout the entire process of drilling, completion, water injection, and oil production, becoming increasingly prominent, especially in the later stages of oilfield development. The types of blockages are complex and diverse, mainly including inorganic scale, organic scale, particulate migration, and water-locking emulsions, among other complex blockages. Inorganic scale is primarily composed of calcium carbonate, while organic scale mainly consists of waxy and asphaltene deposits. Particulate migration is mostly formed by the migration and aggregation of clay particles and silt. These blockages significantly reduce formation permeability, leading to a sharp decline in oil well production, increased water injection pressure in injection wells, and even fluid and production shutdowns, resulting in huge economic losses for oilfield production.

[0003] Currently, domestic and international approaches to address oil and water well blockage primarily employ techniques such as acidizing, hydraulic fracturing, physical deblocking, and bio-enzyme deblocking. Acidizing is highly corrosive to formation rocks and wellbore tubing, easily causing secondary damage; its rapid reaction speed and short effective range make it difficult to achieve deep deblocking, and it easily produces secondary precipitation such as fluorosilicates after acidizing, leading to re-blocking of the formation. Its short effective period makes it difficult to meet the long-term stable production requirements of oilfields. While hydraulic fracturing can improve permeability by creating artificial fractures, its construction process is complex and costly, and it carries risks such as fracture closure and sand blockage. Physical deblocking methods such as hydraulic oscillation and ultrasound cause less damage to the formation, but their energy decays rapidly, their effective radius is small, and their effective period is short, making long-term deblocking impossible. Bio-enzyme deblocking, while environmentally friendly and non-corrosive, has a long action time, limited effectiveness against complex blockages, and high cost, making large-scale application difficult.

[0004] Developing a highly efficient, low-damage, and environmentally friendly unblocking agent for oil and water wells has become a pressing technical challenge in the current oilfield development field. Summary of the Invention

[0005] This invention addresses the shortcomings of existing technologies by providing a highly efficient unblocking agent for oil and water wells and its preparation method. The unblocking agent of this invention has the advantages of good unblocking effect, low corrosion rate, and no secondary pollution.

[0006] The first objective of this invention discloses a highly efficient unblocking agent for oil and water wells, which, by weight percentage, is composed of the following raw materials: Acid-dissolving agent 2-4%; Multi-functional unblocking agent 0.1-0.2%; Strengthen the unblocking agent to 0.2-0.5%; Water balance.

[0007] The acid unblocking agent is one or two of hydrochloric acid, hydrofluoric acid, and citric acid. It should be noted that the concentrations of hydrochloric acid, hydrofluoric acid, and citric acid have been converted to 100%, and unless otherwise specified below, they will be calculated in this manner.

[0008] The structural formula of the multifunctional unblocking agent is as follows: .

[0009] The aforementioned enhanced unblocking agent is sulfonate betaine, comprising one or more of 3-(N,N-dimethyldodecylammonium)propane sulfonate, 3-(N,N-dimethyltetradecylammonium)propane sulfonate, 3-(N,N-dimethylhexadecylammonium)propane sulfonate, and 3-(N,N-dimethyloctadecylammonium)propane sulfonate, with the following structural formula:

[0010] Where R is C 12 H 25 C 14 H 29 C 16 H 33 C 18 H 37 One or more of them.

[0011] The second objective of this invention is to disclose a method for preparing the aforementioned unblocking agent, the method specifically comprising the following steps: S1. Oleic acid, diethylenetriamine, and xylene are added to the first reactor, and the mixture is heated and kept at a constant temperature to carry out the amidation reaction. S2, continue heating to carry out the cyclization reaction; S3. Reduced pressure distillation, cooling, add distilled water, adjust pH to 7-8 with sodium hydroxide, and simultaneously add carbon disulfide and sodium hydroxide aqueous solution dropwise. Maintain pH 7-8 during the reaction process. After the addition is complete, heat to reflux for the reaction. S4. Cool the above mixture to below 10°C to precipitate crystals, centrifuge, and obtain a multifunctional unblocking agent; S5. Water, multi-functional unblocking agent, and enhanced unblocking agent are added sequentially to the second reactor and stirred evenly. Then, acid unblocking agent is added and stirred evenly to obtain a high-efficiency unblocking agent for oil and water wells.

[0012] In this invention, the molar ratio of diethylenetriamine, carbon disulfide and oleic acid is further 1-1.5:0.4-0.6:1; even further, the molar ratio of diethylenetriamine, carbon disulfide and oleic acid is 1.2-1.4:0.45-0.55:1.

[0013] Furthermore, in step S1, the mass ratio of xylene to oleic acid is 0.3-0.5:1.

[0014] Furthermore, the amidation reaction in step S1 is carried out at a temperature of 120-140°C for 2-4 hours.

[0015] Furthermore, the cyclization reaction in step S2 is carried out at a temperature of 170-190°C for 6-12 hours.

[0016] Furthermore, the mass ratio of distilled water to oleic acid in step S3 is 4-6:1.

[0017] Furthermore, the reflux reaction time in step S3 is 1-2 hours.

[0018] A third objective of this invention is to disclose the application of the above-mentioned unblocking agent in unblocking oil and water wells.

[0019] This invention relates to a high-efficiency unblocking agent for oil and water wells, which is a composite unblocking agent. The hydrochloric acid or citric acid in the acid unblocking agent can quickly dissolve formation blockages caused by carbonates, while hydrofluoric acid can dissolve formation blockages caused by mud particles and formation clay minerals, thereby relieving inorganic contamination in oil and water wells. This multifunctional unblocking agent has two functions: a corrosion inhibitor function and a sludge unblocking function. The corrosion inhibitor function reduces the corrosion of the tubing by the acid unblocking agent, based on two principles. Principle 1 is that the multifunctional unblocking agent contains imidazoline functional groups, which attach to the metal surface through hydrophilic groups. Its hydrophobic alkyl chains form a dense protective film, effectively blocking H... + The corrosion inhibition process, which slows down the corrosion rate, is based on the principle that sulfur atoms in the molecule have vacant 3d orbitals. The outer electrons of the metal can feed back to the 3d orbitals of sulfur, forming a stable π-bond structure, reducing the electron cloud density of the metal, making its surface less susceptible to oxidation, and thus further enhancing the corrosion inhibition effect. The multifunctional unblocking agent can be adsorbed at the oil-water interface, reducing interfacial tension. The alkyl chains can enter the sludge and remove it from situ. The enhanced unblocking agent forms worm-like micelles in an acidic environment, thickening the acid solution, sealing high-permeability zones, and achieving diversion and separation. Simultaneously, it reduces oil-water interfacial tension, emulsifies and removes oil from pores. Upon contact with oil, the structure automatically breaks down, facilitating backflow, achieving deep and uniform unblocking without residual damage.

[0020] The beneficial effects and advantages of this invention compared with the prior art are as follows: (1) The unblocking agent of the present invention has a good dissolution effect on natural rock cores, and the dissolution rate can reach 29.3%; (2) The unblocking agent of this invention has a good corrosion inhibition effect, and the corrosion rate can be as low as 0.7 g / (m²). 2 . h); (3) The unblocking agent of the present invention has a good unblocking effect, and the permeability recovery rate can reach 93.6%. Attached Figure Description

[0021] Appendix Figure 1 This is the infrared spectrum of the multifunctional acid D5 in the unblocking agent of this invention. Detailed Implementation

[0022] The technical solution of the present invention will be further described below with reference to specific embodiments: Example 1: Preparation of Multifunctional Unblocking Agent D1 S1. Add 0.1 mol oleic acid, 0.1 mol diethylenetriamine, and 8.5 g xylene to the reactor and keep the temperature at 140℃ for 2 hours. S2. Continue heating to 170℃ and maintain the temperature for 8 hours. S3. Reduced pressure distillation, cooling, add 113g of distilled water, adjust pH to 7-8 with sodium hydroxide, and simultaneously add 0.04mol carbon disulfide and sodium hydroxide aqueous solution dropwise. Maintain pH 7-8 during the reaction process. After the addition is complete, heat and reflux for 2 hours. S4. Cool the above mixture to below 10°C to precipitate crystals, centrifuge, and obtain multifunctional unblocking agent D1.

[0023] Example 2 Preparation of Multifunctional Unblocking Agent D2 S1. Add 0.1 mol oleic acid, 0.15 mol diethylenetriamine, and 14.1 g xylene to the reactor and keep the temperature at 120℃ for 4 hours. S2. Continue heating to 170℃ and maintain the temperature for 12 hours. S3. Reduced pressure distillation, cooling, add 124g of distilled water, adjust pH to 7-8 with sodium hydroxide, and simultaneously add 0.06mol carbon disulfide and sodium hydroxide aqueous solution dropwise. Maintain pH 7-8 during the reaction process. After the addition is complete, heat and reflux for 1h. S4. Cool the above mixture to below 10°C to precipitate crystals, centrifuge, and obtain multifunctional unblocking agent D2.

[0024] Example 3 Preparation of Multifunctional Unblocking Agent D3 S1. Add 0.1 mol oleic acid, 0.12 mol diethylenetriamine, and 9.8 g xylene to the reactor and keep the temperature at 130℃ for 3 hours. S2. Continue heating to 190℃ and maintain the temperature for 6 hours. S3. Reduced pressure distillation, cooling, add 158g of distilled water, adjust pH to 7-8 with sodium hydroxide, and simultaneously add 0.045mol carbon disulfide and sodium hydroxide aqueous solution dropwise. Maintain pH 7-8 during the reaction process. After the addition is complete, heat and reflux for 1.5h. S4. Cool the above mixture to below 10°C to precipitate crystals, centrifuge, and obtain multifunctional unblocking agent D3.

[0025] Example 4 Preparation of Multifunctional Unblocking Agent D4 S1. Add 0.1 mol oleic acid, 0.13 mol diethylenetriamine, and 11 g xylene to the reactor and keep the temperature at 135℃ for 3.5 h. S2. Continue heating to 180℃ and maintain the temperature for 8 hours; S3. Reduced pressure distillation, cooling, add 160g of distilled water, adjust pH to 7-8 with sodium hydroxide, and simultaneously add 0.055mol carbon disulfide and sodium hydroxide aqueous solution dropwise. Maintain pH 7-8 during the reaction process. After the addition is complete, heat and reflux for 2 hours. S4. Cool the above mixture to below 10°C to precipitate crystals, centrifuge, and obtain the multifunctional unblocking agent D4.

[0026] Example 5 Preparation of Multifunctional Unblocking Agent D5 S1. Add 0.1 mol oleic acid, 0.14 mol diethylenetriamine, and 12.4 g xylene to the reactor and keep the temperature at 130℃ for 3 hours. S2. Continue heating to 178℃ and maintain the temperature for 10 hours. S3. Reduced pressure distillation, cooling, add 169g of distilled water, adjust pH to 7-8 with sodium hydroxide, and simultaneously add 0.05mol carbon disulfide and sodium hydroxide aqueous solution dropwise. Maintain pH 7-8 during the reaction process. After the addition is complete, heat and reflux for 2 hours. S4. Cool the above mixture to below 10°C to precipitate crystals, centrifuge to obtain multifunctional unblocking agent D5.

[0027] Example 6 Preparation of High-Efficiency Unblocking Agent 977g of water, 1g of multifunctional unblocking agent D1, and 2g of 3-(N,N-dimethyldodecylammonium)propane sulfonate were added sequentially to the reactor and stirred until homogeneous. Then, 20g of hydrochloric acid was added and stirred until homogeneous to obtain a high-efficiency unblocking agent for oil and water wells.

[0028] Example 7 Preparation of High-Efficiency Unblocking Agent 966g of water, 1g of multifunctional unblocking agent D2, and 3g of 3-(N,N-dimethyltetradecylammonium)propane sulfonate were added sequentially to the reactor and stirred until homogeneous. Then, 30g of citric acid was added and stirred until homogeneous to obtain a high-efficiency unblocking agent for oil and water wells.

[0029] Example 8 Preparation of High-Efficiency Unblocking Agent 974.5g of water, 1.5g of multifunctional unblocking agent D3, and 4g of 3-(N,N-dimethylhexadecylammonium)propane sulfonate were added sequentially to the reactor and stirred until homogeneous. Then, 15g of hydrochloric acid and 5g of hydrofluoric acid were added and stirred until homogeneous to obtain a high-efficiency unblocking agent for oil and water wells.

[0030] Example 9 Preparation of High-Efficiency Unblocking Agent 963g of water, 2g of multifunctional unblocking agent D4, and 5g of 3-(N,N-dimethyloctadecylammonium)propane sulfonate were added to the reactor in sequence and stirred evenly. Then, 20g of citric acid and 10g of hydrofluoric acid were added and stirred evenly to obtain a high-efficiency unblocking agent for oil and water wells.

[0031] Example 10 Preparation of High-Efficiency Unblocking Agent 954g of water, 2g of multifunctional unblocking agent D5, 1g of 3-(N,N-dimethyldodecylammonium)propane sulfonate, 1g of 3-(N,N-dimethyltetradecylammonium)propane sulfonate, 1g of 3-(N,N-dimethylhexadecylammonium)propane sulfonate, and 1g of 3-(N,N-dimethyloctadecylammonium)propane sulfonate were added sequentially to the reactor and stirred until homogeneous. Then, 20g of hydrochloric acid and 20g of hydrofluoric acid were added and stirred until homogeneous to obtain a high-efficiency unblocking agent for oil and water wells.

[0032] Comparative Example 1 The preparation method is the same as in Example 10, except that hydrochloric acid and hydrofluoric acid are not added, and the amount of water added is 994g.

[0033] Comparative Example 2 The preparation method is the same as in Example 10, except that the multifunctional unblocking agent D5 is not added and the amount of water added is 956g.

[0034] Comparative Example 3 The preparation method is the same as in Example 10, except that 3-(N,N-dimethyldodecylammonium)propane sulfonate, 3-(N,N-dimethyltetradecylammonium)propane sulfonate, 3-(N,N-dimethylhexadecylammonium)propane sulfonate, and 3-(N,N-dimethyloctadecylammonium)propane sulfonate are not added, and the amount of water added is 958g.

[0035] Test Example 1 Take several natural sedimentary rock cores with dimensions of 25 mm in diameter and 20 mm in length, and weigh them (m0).

[0036] Take 1600g of samples from Examples 6-10 and Comparative Examples 1-3 and place them in 2000ml plastic beakers. Add 6 natural rock cores to each beaker and place them in an oven at 80℃. Take out one rock core at 2, 4, 6, 8, 10, and 12 hours, rinse, dry, and weigh (m). Calculate the dissolution rate R.

[0037] R = (m0 - m) / m0 × 100% The test results are shown in Table 1.

[0038] Test Example 2 The N80 pads were placed in the samples of Examples 6-10 and Comparative Examples 1-3, and the corrosion rate was tested at 80°C. The specific test method is based on SY / T 5405-2019 "Test Methods and Evaluation Indicators for the Performance of Corrosion Inhibitors for Acidification".

[0039] The test results are shown in Table 2.

[0040] Test Example 3 A natural rock core with dimensions of 25 mm in diameter and 20 mm in length was taken, saturated with formation water, and its permeability K1 was tested.

[0041] Crude oil core samples from a certain oil well were reverse-injected and aged at 90℃ for 72 hours. 1.5 PV of samples from Examples 6-10 and Comparative Examples 1-3 were then injected. Formation water was displaced after 24 hours, and the permeability K2 was tested. Permeability recovery rate was also measured. η = K2 / K1 × 100% The test results are shown in Table 2.

[0042] Table 1. Change of dissolution rate R over time (%)

[0043] As shown in Table 1, the substances that dissolve natural rock cores are mainly acid-based dissolving agents. Hydrochloric acid and citric acid dissolve carbonates, while hydrofluoric acid dissolves silicates. Examples 10 and 2 demonstrate that the multifunctional acid has a slow-release effect on dissolving marble.

[0044] Table 2. Results of Corrosion Rate and Permeability Recovery Rate Tests

[0045] Table 2 shows that the main corrosive agent for metals is the acid unblocking agent, and the addition of multifunctional acid significantly slows down corrosion. Comparative Example 1 and Comparative Example 2 show good unblocking effects because both the multifunctional unblocking agent and the enhanced unblocking agent can unblock contamination caused by crude oil. Comparative Example 3 shows a slight unblocking effect because the acid unblocking agent has a certain dissolving effect on the core, thereby increasing the core permeability.

[0046] Test Example 4 The multifunctional acid D5 in the unblocking agent of this invention was characterized by infrared spectroscopy, and the results are as follows: Figure 1 As shown.

[0047] Figure 1 In the figure, 3424 cm⁻¹ is the stretching vibration peak, 1636 cm⁻¹ is the stretching vibration peak, and 1112 cm⁻¹ is the stretching vibration peak.

Claims

1. A highly efficient unblocking agent for oil and water wells, characterized in that, The aforementioned high-efficiency unblocking agent for oil and water wells is composed of the following raw materials by weight percentage: Acid-dissolving agent 2-4%; Multi-functional unblocking agent 0.1-0.2%; Strengthen the unblocking agent to 0.2-0.5%; Water balance; The acid unblocking agent is one or two of hydrochloric acid, hydrofluoric acid, and citric acid, and the concentrations of hydrochloric acid, hydrofluoric acid, and citric acid have all been converted to 100%. The structural formula of the multifunctional unblocking agent is as follows: ； The aforementioned enhanced unblocking agent is betaine sulfonate.

2. The high-efficiency unblocking agent for oil and water wells as described in claim 1, characterized in that, The sulfonate betaine includes one or more of 3-(N,N-dimethyldodecylammonium)propane sulfonate, 3-(N,N-dimethyltetradecylammonium)propane sulfonate, 3-(N,N-dimethylhexadecylammonium)propane sulfonate, and 3-(N,N-dimethyloctadecylammonium)propane sulfonate.

3. The preparation method of the high-efficiency unblocking agent for oil and water wells as described in claim 1 or 2, characterized in that, The preparation method specifically includes the following steps: S1. Oleic acid, diethylenetriamine, and xylene are added to the first reactor, and the mixture is heated and kept at a constant temperature to carry out the amidation reaction. S2, continue heating to carry out the cyclization reaction; S3. Reduced pressure distillation, cooling, add distilled water, adjust pH to 7-8 with sodium hydroxide, and simultaneously add carbon disulfide and sodium hydroxide aqueous solution dropwise. Maintain pH 7-8 during the reaction process. After the addition is complete, heat to reflux for the reaction. S4. Cool the above mixture to below 10°C to precipitate crystals, centrifuge, and obtain a multifunctional unblocking agent; S5. Water, multi-functional unblocking agent, and enhanced unblocking agent are added sequentially to the second reactor and stirred evenly. Then, acid unblocking agent is added and stirred evenly to obtain a high-efficiency unblocking agent for oil and water wells.

4. The preparation method according to claim 3, characterized in that, The molar ratio of diethylenetriamine, carbon disulfide and oleic acid is 1-1.5:0.4-0.6:

1.

5. The preparation method according to claim 4, characterized in that, The molar ratio of diethylenetriamine, carbon disulfide and oleic acid is 1.2-1.4:0.45-0.55:

1.

6. The preparation method according to claim 3, characterized in that, In step S1, the mass ratio of xylene to oleic acid is 0.3-0.5:

1.

7. The preparation method according to claim 3, characterized in that, The amidation reaction in step S1 is carried out at a temperature of 120-140°C for 2-4 hours.

8. The preparation method according to claim 3, characterized in that, The cyclization reaction in step S2 is carried out at a temperature of 170-190°C for 6-12 hours.

9. The preparation method according to claim 3, characterized in that, The mass ratio of distilled water to oleic acid in step S3 is 4-6:1, and the reflux reaction time in step S3 is 1-2 hours.

10. The application of the unblocking agent as described in claim 1 or 2 in unblocking oil and water wells.

Images