Iron ion stabilizer for oil field acidification and preparation method thereof

Abstract

The application belongs to the technical field of oil exploitation, and particularly relates to an iron ion stabilizer for oil field acidification and a preparation method thereof. The iron ion stabilizer for oil field acidification is composed of the following raw materials in percentage by weight: 0.1-0.3% of polymeric carboxylic acid, 0.1-0.3% of diethylenetriamine penta-methylene phosphonic acid, 0.05-0.1% of gluconic acid, 0.02-0.05% of isoascorbic acid, and the balance of water. The structural formula of the polymeric carboxylic acid is as follows: wherein n is a natural number greater than 2. The iron ion stabilizer has the advantages of strong iron ion stabilizing capacity and high temperature resistance. The highest iron ion stabilizing capacity at room temperature reaches 242 mg / ml, and the highest iron ion stabilizing capacity after constant temperature at 120 DEG C for 4 hours reaches 238 mg / ml.

Description

Technical Field

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

[0002] Acidizing is one of the main measures for stabilizing and increasing the production of oil and gas wells, and for stabilizing and increasing the injection of water wells. It uses acid to remove contaminants near the bottom of production wells and injection wells, restore the permeability of the formation or dissolve the cement of the formation rocks to improve the permeability of the formation, and unclog the fluid seepage channels, thereby restoring and increasing the production capacity of the well.

[0003] During acidizing operations in oil and water wells, the high concentration of acid solution dissolves iron compounds on the surfaces of pipelines and equipment during stirring and pumping. Once inside the formation, this acid further erodes iron and clay minerals in the rock. Even with corrosion inhibitors, some iron will still be dissolved. This dissolved iron in the solution is generally in the form of Fe. 2+ and Fe 3+ The acid solution exists in a certain state. As the acid continues to react with the formation rocks, the effective concentration of the acid gradually decreases, and the pH value increases. When the pH value of the acid solution rises to 2.2, Fe(OH)3 precipitate begins to form; when the pH value of the acid solution continues to rise to 3.2, all dissolved Fe... 3+ Precipitation was complete; when the pH of the acid solution continued to rise to 7.7, Fe... 2+ While Fe(OH)₂ precipitation will also occur, it is not considered during acidizing operations because the pH of the acid solution is less than 6. Once Fe(OH)₃ precipitation forms, it can clog formation pores and oil and gas permeation channels, thereby reducing the effectiveness of acidizing and oil and gas production. To prevent iron precipitation when the acid solution becomes residual acid, iron ion stabilizers are often added to the acid solution in acidizing technology to prevent the formation of gel-like ferric hydroxide precipitate, thus preventing damage to the oil and gas reservoir and improving the effectiveness of acidizing.

[0004] Current iron ion stabilizers generally suffer from poor iron ion stabilization and insufficient high-temperature resistance. They are prone to decomposition and failure under high-temperature deep well conditions, failing to effectively chelate iron ions and causing precipitation to reform, which directly affects the acidizing and production enhancement effect. Summary of the Invention

[0005] This invention addresses the shortcomings of the prior art by providing an iron ion stabilizer for oilfield acidizing and its preparation method. The iron ion stabilizer of this invention has the advantages of strong iron ion stabilization ability and high temperature resistance; its iron ion stabilization ability at room temperature reaches a maximum of 242 mg / ml; after being kept at 120℃ for 4 hours, the stable iron ion concentration reaches a maximum of 238 mg / ml.

[0006] The first objective of this invention discloses an iron ion stabilizer for oilfield acidizing and its preparation method. The iron ion stabilizer for oilfield acidizing, by weight percentage, is composed of the following raw materials:

[0007] Polycarboxylic acid 0.1-0.3%;

[0008] Diethylenetriaminepentamethylphosphonic acid 0.1-0.3%;

[0009] Gluconic acid 0.05-0.1%;

[0010] Isoascorbic acid 0.02-0.05%;

[0011] Water balance;

[0012] The structural formula of the polymeric carboxylic acid is as follows:

[0013]

[0014] Where n is a natural number greater than 2.

[0015] The second objective of this invention is to provide a method for preparing the aforementioned iron ion stabilizer for oilfield acidizing, the method specifically comprising the following steps:

[0016] (1) Add 3,5-diaminobenzoic acid and solvent to the first reactor, stir to dissolve, add 3,3'-dichloropentanoic acid, stir to dissolve, and adjust the pH to 7-8;

[0017] (2) Heat and keep warm during the reaction, maintaining pH 7-8;

[0018] (3) Vacuum distillation yields a solid, namely polymeric carboxylic acid;

[0019] (4) Polycarboxylic acid, diethylenetriaminepentamethylphosphonic acid, gluconic acid, isoascorbic acid and water are added sequentially to the second reactor, stirred to dissolve, and the pH is adjusted to 6-7 to obtain an iron ion stabilizer for oilfield acidification.

[0020] Furthermore, the mass ratio of the solvent, 3,3'-dichloropentanoic acid, to 3,5-diaminobenzoic acid is 12-15:0.9-1.3:1.

[0021] Furthermore, the solvent is one of methanol, ethanol, propanol, and isopropanol.

[0022] Furthermore, the heating and heat preservation reaction time is 2-6 hours and the temperature is 50-70℃.

[0023] This invention relates to a compound iron ion stabilizer. The polymeric carboxylic acid contains a large number of carboxyl groups, exhibiting a strong chelating effect. It can form a stable ring structure with iron ions, thus preventing iron ions from precipitating from the solution. Furthermore, the presence of an amino group in the molecule allows the lone pair electrons on the nitrogen atom to form coordinate bonds with iron ions, further enhancing the stability of the chelation. Diethylenetriamine pentamethylphosphonic acid forms a multidentate chelate with the amino group through dense phosphonic acid groups, firmly locking iron ions in place. Simultaneously, it prevents the aggregation of any potential micro-precipitates through lattice distortion and dispersion, and reduces iron ion generation at the source through corrosion inhibition. Gluconic acid forms a stable ring structure with iron ions through its polyhydroxy and carboxyl groups, locking them in the solution. It also acts as a dispersant, preventing the aggregation of micro-precipitate particles and effectively inhibiting the formation of iron hydroxide precipitate. Isoascorbic acid exerts a strong reducing effect through its olefinic structure, reducing easily hydrolyzed and precipitated Fe. 3+ Reduced to more stable Fe 2+ .

[0024] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0025] (1) The iron ion stabilizer of the present invention has a strong ability to stabilize iron ions, which can reach up to 242 mg / ml;

[0026] (2) The iron ion stabilizer of the present invention has strong temperature resistance. After being kept at 120°C for 4 hours, the stabilized iron ion concentration can reach up to 238 mg / ml. Detailed Implementation

[0027] The present invention will be further described below with reference to specific embodiments:

[0028] Example 1

[0029] (1) Add 10g of 3,5-diaminobenzoic acid and 150g of methanol to the reactor, stir to dissolve, add 9g of 3,3'-dichloropentanoic acid, stir to dissolve, and adjust the pH to 7-8;

[0030] (2) Heat to 70℃ and keep the temperature for 2 hours, maintaining pH 7-8 during the reaction;

[0031] (3) Reduced pressure distillation yields polycarboxylic acid S1.

[0032] (4) Add 1g of polycarboxylic acid S1, 1g of diethylenetriamine pentamethylphosphonic acid, 1g of gluconic acid, 0.5g of isoascorbic acid and 996.5g of water to the reactor in sequence, stir to dissolve, adjust the pH to 6-7, and obtain the iron ion stabilizer for oilfield acidification.

[0033] Example 2

[0034] (1) Add 10g of 3,5-diaminobenzoic acid and 120g of propanol to the reactor, stir to dissolve, add 13g of 3,3'-dichloropentanoic acid, stir to dissolve, and adjust the pH to 7-8;

[0035] (2) Heat to 65℃ and keep the reaction at that temperature for 3 hours, maintaining the pH at 7-8 during the reaction.

[0036] (3) Reduced pressure distillation yields polymeric carboxylic acid S2.

[0037] (4) Add 1g of polycarboxylic acid S2, 3g of diethylenetriamine pentamethylphosphonic acid, 0.5g of gluconic acid, 0.2g of isoascorbic acid and 995.3g of water to the reactor in sequence, stir to dissolve, adjust the pH to 6-7, and obtain the iron ion stabilizer for oilfield acidification.

[0038] Example 3

[0039] (1) Add 10g of 3,5-diaminobenzoic acid and 130g of ethanol to the reactor, stir to dissolve, add 10.7g of 3,3'-dichloropentanoic acid, stir to dissolve, and adjust the pH to 7-8;

[0040] (2) Heat to 50°C and keep the reaction at that temperature for 6 hours, maintaining the pH at 7-8 during the reaction.

[0041] (3) Reduced pressure distillation yields polymeric carboxylic acid S3.

[0042] (4) Add 2g of polycarboxylic acid S3, 2g of diethylenetriamine pentamethylphosphonic acid, 0.7g of gluconic acid, 0.4g of isoascorbic acid and 994.9g of water to the reactor in sequence, stir to dissolve, adjust pH to 6-7, and obtain iron ion stabilizer for oilfield acidification.

[0043] Example 4

[0044] (1) Add 10g of 3,5-diaminobenzoic acid and 135g of isopropanol to the reactor, stir to dissolve, add 10.5g of 3,3'-dichloropentanoic acid, stir to dissolve, and adjust the pH to 7-8;

[0045] (2) Heat to 60℃ and keep the reaction at that temperature for 5 hours, maintaining the pH at 7-8 during the reaction.

[0046] (3) Distillation under reduced pressure yields polycarboxylic acid S4.

[0047] (4) Add 2g of polycarboxylic acid S4, 2.3g of diethylenetriamine pentamethylphosphonic acid, 0.8g of gluconic acid, 0.3g of isoascorbic acid and 994.6g of water to the reactor in sequence, stir to dissolve, adjust the pH to 6-7, and obtain the iron ion stabilizer for oilfield acidification.

[0048] Example 5

[0049] (1) Add 10g of 3,5-diaminobenzoic acid and 140g of ethanol to the reactor, stir to dissolve, add 12g of 3,3'-dichloropentanoic acid, stir to dissolve, and adjust the pH to 7-8;

[0050] (2) Heat to 60℃ and keep the reaction at that temperature for 4 hours, maintaining the pH at 7-8 during the reaction.

[0051] (3) Reduced pressure distillation yields polycarboxylic acid S5.

[0052] (4) Add 3g of polycarboxylic acid S5, 1.5g of diethylenetriaminepentamethylphosphonic acid, 1g of gluconic acid, 0.4g of isoascorbic acid and 994.1g of water to the reactor in sequence, stir to dissolve, adjust the pH to 6-7, and obtain the iron ion stabilizer for oilfield acidification.

[0053] Example 6

[0054] (1) Add 10g of 3,5-diaminobenzoic acid and 142g of isopropanol to the reactor, stir to dissolve, add 11.3g of 3,3'-dichloropentanoic acid, stir to dissolve, and adjust the pH to 7-8;

[0055] (2) Heat to 62℃ and keep the temperature for 4 hours, maintaining pH 7-8 during the reaction;

[0056] (3) Reduced pressure distillation yields polymeric carboxylic acid S6.

[0057] (4) Add 3g of polycarboxylic acid S6, 3g of diethylenetriamine pentamethylphosphonic acid, 0.8g of gluconic acid, 0.4g of isoascorbic acid and 992.8g of water to the reactor in sequence, stir to dissolve, adjust pH to 6-7, and obtain iron ion stabilizer for oilfield acidification.

[0058] Comparative Example 1

[0059] The preparation method is the same as in Example 1, except that no polymeric carboxylic acid S1 is added.

[0060] Comparative Example 2

[0061] The preparation method is the same as in Example 1, except that diethylenetriaminepentimidephosphonic acid is not added.

[0062] Comparative Example 3

[0063] The preparation method is the same as in Example 1, except that gluconic acid and isoascorbic acid are not added.

[0064] Test Example 1

[0065] The room-temperature stabilization ability (N1) of the iron ion stabilizer of this invention was tested. The test method referred to SY / T 6571-2012 "Performance Evaluation Method of Iron Ion Stabilizers for Acidification", except that the undiluted solution was used directly in the test without dilution. The test results are shown in Table 1.

[0066] Test Example 2

[0067] The iron ion stabilizer of the present invention was placed in an oven at 120°C for 4 hours and then removed. Its ability to stabilize iron ions (N2) was tested according to the method in Test Example 1. The test results are shown in Table 1.

[0068] Table 1. Test results of iron ion stabilization ability at room temperature and 120℃

[0069]

[0070] As can be seen from Table 1:

[0071] Compared to Example 1, the room-temperature ferric ion stabilization capacity (N1) of Comparative Examples 1, 2, and 3 decreased by 47, 22, and 10 mg / ml, respectively, indicating that the stabilizing effect on ferric ions was in the order of polycarboxylic acid > diethylenetriaminepentamethylphosphonic acid > gluconic acid and isoascorbic acid. The N2 in Comparative Examples 1, 2, and 3 decreased by 3, 3, and 12 mg / ml compared to N1, respectively, indicating that gluconic acid and isoascorbic acid played a significant role in ferric ion stabilization at high temperatures.

[0072] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. An iron ion stabilizer for oilfield acidizing, characterized in that, The iron ion stabilizer, by weight percentage, is composed of the following raw materials: Polycarboxylic acid 0.1-0.3%; Diethylenetriaminepentamethylphosphonic acid 0.1-0.3%; Gluconic acid 0.05-0.1%; Isoascorbic acid 0.02-0.05%; Water balance; The structural formula of the polymeric carboxylic acid is as follows: ， Where n is a natural number greater than 2.

2. The method for preparing the iron ion stabilizer according to claim 1, characterized in that, The preparation method specifically includes the following steps: (1) Add 3,5-diaminobenzoic acid and solvent to the first reactor, stir to dissolve, add 3,3'-dichloropentanoic acid, stir to dissolve, and adjust the pH to 7-8; (2) Heat and keep warm during the reaction, maintaining pH 7-8; (3) Vacuum distillation yields a solid, namely polymeric carboxylic acid; (4) Polycarboxylic acid, diethylenetriaminepentamethylphosphonic acid, gluconic acid, isoascorbic acid and water are added sequentially to the second reactor, stirred to dissolve, and the pH is adjusted to 6-7 to obtain an iron ion stabilizer for oilfield acidification.

3. The method for preparing the iron ion stabilizer according to claim 2, characterized in that, The mass ratio of the solvent, 3,3'-dichloropentanoic acid, to 3,5-diaminobenzoic acid is 12-15. 0.9-1.3：1。 4. The method for preparing the iron ion stabilizer according to claim 2 or 3, characterized in that, The solvent is one of methanol, ethanol, propanol, and isopropanol.

5. The method for preparing the iron ion stabilizer according to claim 2, characterized in that, The heating and heat preservation reaction time is 2-6 hours and the temperature is 50-70℃.

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