Purine Mannich base corrosion inhibitor, completion fluid as well as preparation and application of purine Mannich base corrosion inhibitor and completion fluid

Abstract

The invention relates to the technical field of oilfield development, in particular to a purine Mannich base corrosion inhibitor, a completion fluid and preparation and application of the purine Mannich base corrosion inhibitor and the completion fluid. The preparation method of the purine Mannich base corrosion inhibitor comprises the following steps: adding aldehyde, ketone and purine into methanol, fully mixing and dissolving, adding concentrated hydrochloric acid into a reaction system, adjusting the pH value of the reaction system to 1-4, and carrying out Mannich reaction; and after the Mannich reaction is finished, cooling the reaction system to room temperature, removing the solvent in the system, recrystallizing and filtering to obtain the purine Mannich base corrosion inhibitor. The purine Mannich base corrosion inhibitor can adapt to the high-temperature condition of 200 DEG C or above, and has important significance on well completion operation of high-temperature deep wells and ultra-deep wells.

Description

Technical Field

[0001] This application relates to the technical field of oilfield development, specifically to a purine-based Mannich base corrosion inhibitor, a completion fluid, and its preparation and application. Background Technology

[0002] In oilfield well completion operations, high-density completion fluid systems are often required to balance formation pressure and maintain wellbore stability. Brine completion fluid is a system formulated using inorganic salts as the main compounds. Due to the micro-electrolysis of salt ions, brine completion fluid systems often exhibit high corrosiveness. Combined with the problem of corrosive gas channeling, this can cause corrosion of the casing and tubing. Excessive corrosion of the casing and tubing can severely damage oilfield production and cause significant economic losses.

[0003] To minimize losses caused by completion fluid corrosion, corrosion inhibitors need to be added to high-density brine completion fluid systems to reduce the corrosion of downhole metals. Mannich bases are β-amino (carbonyl) compounds, typically prepared via ketamine synthesis. Mannich bases exhibit excellent corrosion inhibition under acidic conditions and hold an important position in the research of corrosion inhibitors for acidic media, possessing significant development value and application prospects. However, currently available Mannich base corrosion inhibitors only meet the requirements for temperatures not exceeding 160℃; at higher temperatures, they are ineffective in inhibiting completion fluid corrosion. Summary of the Invention

[0004] To provide a corrosion inhibitor suitable for high-temperature conditions, this application provides a purine-based Mannich base corrosion inhibitor, a completion fluid, and its preparation and application. The technical solution adopted in this application is as follows:

[0005] In a first aspect, this application provides a purine-based Mannich base corrosion inhibitor, the structural formula of which is shown in formula (Ⅰ):

[0006]

[0007]

[0008] Where R1 is H or

[0009] n = 0 to 2;

[0010] R2 is

[0011] Secondly, this application also relates to a method for preparing the above-mentioned purine-based Mannich base corrosion inhibitor, comprising:

[0012] Aldehydes, ketones and purines are added to methanol, mixed thoroughly and dissolved, and then concentrated hydrochloric acid is added to the reaction system to adjust the pH of the reaction system to 1-4 to carry out the Mannich reaction.

[0013] After the Mannich reaction is completed, the reaction system is cooled to room temperature, the solvent in the system is removed, recrystallized and filtered to obtain a purine-based Mannich base corrosion inhibitor.

[0014] In a specific embodiment, optionally, the molar ratio of the aldehyde, ketone and purine is (1.2-1.5):(1.1-1.2):1.

[0015] In a specific implementation, optionally, the temperature of the Mannich reaction is 85–95°C and the reaction time is 6–12 h.

[0016] In a specific implementation, optionally, the aldehyde includes any one or more of formaldehyde, acetaldehyde, and phenylacetaldehyde.

[0017] In a specific embodiment, optionally, the ketone includes any one or more of acetone, cyclohexanone, and acetophenone.

[0018] Thirdly, this application also relates to the application of the aforementioned purine-based Mannich base corrosion inhibitors in completion fluids.

[0019] Fourthly, this application also relates to a completion fluid comprising the aforementioned purine-based Mannich base corrosion inhibitor.

[0020] In a specific implementation, optionally, the mass percentage of the purine-based Mannich base corrosion inhibitor is 1% to 10% based on the mass of the completion fluid.

[0021] Fifthly, this application also relates to the application of the aforementioned completion fluid in oilfield completion operations.

[0022] In summary, the advantages of this application over the prior art include:

[0023] This application describes a purine-based Mannich base corrosion inhibitor prepared from aldehydes, ketones, and purines via the Mannich reaction. This inhibitor exhibits excellent corrosion inhibition under high temperature and strong acid conditions. Compared to traditional commercially available corrosion inhibitors, the purine-based Mannich base corrosion inhibitor in this application can reduce the corrosion efficiency of N80 carbon steel and P110 carbon steel to 1 g / m³ at temperatures ranging from 140 to 230°C. -2 ·h -1 The following is a summary of the findings. Furthermore, this corrosion inhibitor requires a small dosage and exhibits good corrosion inhibition during actual use. At a temperature of 230℃, when the addition amount of the purine-based Mannich base corrosion inhibitor is 5%, it can reduce the corrosion efficiency of N80 carbon steel and P110 carbon steel to 5 g / m³. -2 ·h -1The following applies: When the addition amount of purine-based Mannich base corrosion inhibitor is 8%, the corrosion efficiency of N80 carbon steel and P110 carbon steel can be reduced to 1 g / m. -2 ·h -1 Therefore, it is possible to further reduce usage costs. Detailed Implementation

[0024] Yang Xiaofu et al. synthesized the Mannich base reaction product of lauric acid imidazoline, trioxymethylene and acetophenone as reactants. Static weight loss analysis and electrochemical tests showed that the corrosion inhibitor achieved corrosion inhibition rates of 94.18%, 88.16% and 63.54% in 10% hydrochloric acid solution at a dosage of 1250 mg / L and corrosion temperatures of 40℃, 60℃ and 80℃, respectively.

[0025] Zhang Fenghua et al. obtained Mannich's base acidification corrosion inhibitor by using acetophenone, formaldehyde, and benzyltriethylammonium chloride as raw materials and condensing them into aldehydes, ketones, and amines. Laboratory static corrosion plates and electrochemical impedance spectroscopy results showed that when the amount of corrosion inhibitor added was 0.7% and the temperature of the corrosive medium was 50℃, 60℃, 70℃, 80℃, and 90℃, the corrosion inhibition efficiency gradually decreased with increasing temperature, eventually dropping to 80%.

[0026] Chinese patent CN110982508A discloses a Mannich base acidification corrosion inhibitor and its preparation method. This Mannich base acidification corrosion inhibitor modifies the corrosion inhibition performance and applicable temperature by introducing benzene / naphthalene / anthracite rings with different adsorption capacities through changing the quaternizing reagent. However, this Mannich base acidification corrosion inhibitor can only maintain good slow-release properties and solubility / dispersion in environments below 140℃.

[0027] In summary, the inventors have discovered that the environmental temperature range for the corrosion inhibition effect of Mannich bases as described in existing technologies is generally quite limited. For well completion operations in high-temperature deep and ultra-deep wells, the temperature typically reaches above 200°C, while the applicable temperature range for current Mannich base corrosion inhibitors is generally below 160°C, making them unsuitable for well completion operations in high-temperature deep and ultra-deep wells.

[0028] Based on the above problems, the inventors conducted further research and development, resulting in this invention.

[0029] The present application will be described in detail below through specific embodiments and comparative examples:

[0030] Example 1

[0031] (1) Preparation of purine-based Mannich base corrosion inhibitors

[0032] 1.2 mol of formaldehyde and 1.2 mol of acetophenone were added to 100 mL of methanol, followed by 1 mol of purine. After thorough shaking to dissolve, concentrated hydrochloric acid was added to adjust the pH of the reaction system to 3. The temperature of the reaction system was then raised to 90 °C and maintained at this temperature for 6 hours. After the reaction was completed, the reaction system was cooled to room temperature, and the solvent was removed by rotary evaporation. Recrystallization was then performed, followed by filtration, and the filter cake was vacuum dried to obtain the purine-based Mannich base corrosion inhibitor.

[0033] The structural formula of the purine-based Mannich base corrosion inhibitor in this embodiment is shown in formula (II):

[0034]

[0035] (2) Evaluation of corrosion inhibition performance

[0036] The completion fluid is prepared according to the following process:

[0037] Add 200g zinc chloride, 79g calcium chloride, and 30g zinc bromide to 100mL of water, dissolve and mix thoroughly to obtain the completion fluid. The density of the completion fluid is 2.0g / cm³. 3 .

[0038] The purine-based Mannich base corrosion inhibitors used in this embodiment were added to the above completion fluid at different dosages. Then, according to industry standard SY / T 5273-2000, the fluids were contacted at 230℃ and pH 3 for 72 hours to evaluate their corrosion inhibition performance on N80 carbon steel. The evaluation results of the purine-based Mannich base corrosion inhibitors and commercially available Mannich base corrosion inhibitors at different dosages are shown in Table 1.

[0039] Table 1. Evaluation results of purine-based Mannich base corrosion inhibitors and commercially available Mannich base corrosion inhibitors at different dosages in Example 1.

[0040]

[0041]

[0042] Table 1 shows that, under strong acid conditions at 140℃, the purine-based Mannich base corrosion inhibitor of this application exhibits a significant protective effect on N80 carbon steel compared to commercially available Mannich base corrosion inhibitors, and the protective effect becomes more pronounced with increasing dosage. In contrast, commercially available Mannich base corrosion inhibitors, at a dosage of 5%, still exhibit a corrosion rate of 14.12 g / m³. -2 ·h -1 .

[0043] Example 2

[0044] The difference between this embodiment and Example 1 is that, in (1), the preparation of the purine-based Mannich base corrosion inhibitor includes:

[0045] 1.35 mol of formaldehyde and 1.18 mol of acetone were added to 100 mL of methanol, followed by 1 mol of purine. After thorough shaking to dissolve, concentrated hydrochloric acid was added to adjust the pH to 1. The reaction mixture was then heated to 88 °C and maintained at this temperature for 10 hours. After the reaction was complete, the mixture was cooled to room temperature, and the solvent was removed by rotary evaporation. Recrystallization was then performed, followed by filtration. Finally, the filter cake was vacuum dried to obtain the purine-based Mannich base corrosion inhibitor.

[0046] The structural formula of the purine-based Mannich base corrosion inhibitor in this embodiment is shown in formula (Ⅲ):

[0047]

[0048] In this embodiment, the preparation process of the completion fluid is the same as in Example 1. The purine-based Mannich base corrosion inhibitor from this embodiment was added to the above completion fluid at different dosages. Then, according to industry standard SY / T 5273-2000, the fluid was contacted at 230℃ and pH 3 for 72 hours to evaluate its corrosion inhibition performance on P110 carbon steel. The evaluation results of the purine-based Mannich base corrosion inhibitor and commercially available Mannich base corrosion inhibitor at different dosages are shown in Table 2.

[0049] Table 2. Evaluation results of purine-based Mannich base corrosion inhibitors and commercially available Mannich base corrosion inhibitors at different dosages in Example 2.

[0050]

[0051] Table 2 shows that, under strong acid conditions at 150℃, the purine-based Mannich base corrosion inhibitor of this application exhibits a significant protective effect on P110 carbon steel compared to commercially available Mannich base corrosion inhibitors, and the protective effect becomes more pronounced with increasing dosage. In contrast, commercially available Mannich base corrosion inhibitors, at a dosage of 8%, still exhibit a corrosion rate of 20.1 g / m³. -2 ·h -1 .

[0052] Example 3

[0053] The difference between this embodiment and Example 1 is that, in (1), the preparation of the purine-based Mannich base corrosion inhibitor includes:

[0054] 1.4 mol of acetaldehyde and 1.1 mol of cyclohexanone were added to 100 mL of methanol, followed by 1 mol of purine. After thorough shaking to dissolve, concentrated hydrochloric acid was added to adjust the pH to 4. The reaction mixture was then heated to 90 °C and maintained at this temperature for 8 hours. After the reaction was complete, the mixture was cooled to room temperature, and the solvent was removed by rotary evaporation. Recrystallization was then performed, followed by filtration. Finally, the filter cake was vacuum dried to obtain the purine-based Mannich base corrosion inhibitor.

[0055] The structural formula of the purine-based Mannich base corrosion inhibitor in this embodiment is shown in formula (Ⅳ):

[0056]

[0057] In this embodiment, the preparation process of the completion fluid is the same as in Example 1. The purine-based Mannich base corrosion inhibitor from this embodiment was added to the above completion fluid at different dosages. Then, according to industry standard SY / T 5273-2000, the fluid was contacted at 230℃ and pH 3 for 72 hours to evaluate its corrosion inhibition performance on P110 carbon steel. The evaluation results of the purine-based Mannich base corrosion inhibitor and commercially available Mannich base corrosion inhibitor at different dosages are shown in Table 3.

[0058] Table 3. Evaluation results of purine-based Mannich base corrosion inhibitors and commercially available Mannich base corrosion inhibitors at different addition amounts in Example 3.

[0059]

[0060]

[0061] Table 3 shows that, under strong acid conditions at 160℃, the purine-based Mannich base corrosion inhibitor of this application exhibits a significant protective effect on P110 carbon steel compared to commercially available Mannich base corrosion inhibitors, and the protective effect becomes more pronounced with increasing dosage. In contrast, commercially available Mannich base corrosion inhibitors, even at a dosage of 9%, still show a corrosion rate of 24.31 g / m³. -2 ·h -1 .

[0062] Example 4

[0063] The difference between this embodiment and Example 1 is that, in (1), the preparation of the purine-based Mannich base corrosion inhibitor includes:

[0064] 1.5 mol of phenylacetaldehyde and 1.1 mol of acetone were added to 100 mL of methanol, followed by 1 mol of purine. After thorough shaking to dissolve, concentrated hydrochloric acid was added to adjust the pH to 4. The reaction mixture was heated to 95°C and maintained at this temperature for 6 hours. After the reaction was complete, the mixture was cooled to room temperature, and the solvent was removed by rotary evaporation. Recrystallization was then performed, followed by filtration. The filter cake was then vacuum dried to obtain the purine-based Mannich base corrosion inhibitor.

[0065] The structural formula of the purine-based Mannich base corrosion inhibitor in this embodiment is shown in formula (V):

[0066]

[0067] In this embodiment, the preparation process of the completion fluid is the same as in Example 1. The purine-based Mannich base corrosion inhibitor from this embodiment was added to the above completion fluid at different dosages. Then, according to industry standard SY / T 5273-2000, the fluid was contacted at 230℃ and pH 3 for 72 hours to evaluate its corrosion inhibition performance on N80 carbon steel. The evaluation results of the purine-based Mannich base corrosion inhibitor and commercially available Mannich base corrosion inhibitor at different dosages are shown in Table 4.

[0068] Table 4. Evaluation results of purine-based Mannich base corrosion inhibitors and commercially available Mannich base corrosion inhibitors at different dosages in Example 4.

[0069]

[0070] As shown in Table 3, under strong acid conditions at 230℃, compared to commercially available Mannich base corrosion inhibitors, the purine-based Mannich base corrosion inhibitor of this application, when added at an amount of 8%–10%, can reduce the corrosion rate of N80 carbon steel to 1 g / m. -2 ·h -1 The protective effect becomes increasingly significant with increasing dosage. However, when the dosage of purine-based Mannich base corrosion inhibitors exceeds 10%, the corrosion rate tends to decrease. Even with a 15% dosage of commercially available Mannich base corrosion inhibitor, the corrosion rate still reaches 33.71 g / m³. -2 ·h -1 .

[0071] Example 5

[0072] The difference between this embodiment and Example 1 is that, in (1), the preparation of the purine-based Mannich base corrosion inhibitor includes:

[0073] 1.5 mol of phenylacetaldehyde and 1.2 mol of acetophenone were added to 100 mL of methanol, followed by 1 mol of purine. After thorough shaking to dissolve, concentrated hydrochloric acid was added to adjust the pH of the reaction system to 3. The temperature of the reaction system was then raised to 95 °C and maintained at this temperature for 9 hours. After the reaction was completed, the reaction system was cooled to room temperature, and the solvent was removed by rotary evaporation. Then, recrystallization was performed, filtered, and the filter cake was vacuum dried to obtain the purine-based Mannich base corrosion inhibitor.

[0074] The structural formula of the purine-based Mannich base corrosion inhibitor in this embodiment is shown in formula (VI):

[0075]

[0076] In this embodiment, the preparation process of the completion fluid is the same as in Example 1. The purine-based Mannich base corrosion inhibitor from this embodiment was added to the above completion fluid at different dosages. Then, according to industry standard SY / T 5273-2000, the fluid was contacted at 230℃ and pH 3 for 72 hours to evaluate its corrosion inhibition performance on P110 carbon steel. The evaluation results of the purine-based Mannich base corrosion inhibitor and commercially available Mannich base corrosion inhibitor at different dosages are shown in Table 5.

[0077] Table 5. Evaluation results of the corrosion inhibitor and commercially available Mannich base corrosion inhibitor in Example 5 at different dosages.

[0078]

[0079] Table 5 shows that under strong acid conditions at 230℃, the addition amount of the purine-based Mannich base corrosion inhibitor of this application, at 8%–10%, can reduce the corrosion rate of P110 carbon steel to below 1%. However, when the addition amount of the purine-based Mannich base corrosion inhibitor exceeds 10%, the corrosion rate tends to increase. A comprehensive comparison of Tables 1–5 shows that as the temperature increases from 140℃ to 230℃, under the same conditions, the corrosion inhibition effect of commercially available Mannich base corrosion inhibitors decreases significantly, while the purine-based Mannich base corrosion inhibitor of this application exhibits excellent adaptability to high temperatures.

[0080] Example 6

[0081] The difference between this embodiment and Embodiment 1 is that, in the preparation process of the purine-based Mannich base corrosion inhibitor, phenylacetaldehyde is used instead of formaldehyde, and cyclohexyl ketone is used instead of acetophenone.

[0082] The structural formula of the purine-based Mannich base corrosion inhibitor in this embodiment is shown in formula (VII):

[0083]

[0084] In this embodiment, the preparation process of the completion fluid is the same as in Example 1. The purine-based Mannich base corrosion inhibitor from this embodiment was added to the above completion fluid at different dosages. Then, according to industry standard SY / T 5273-2000, the fluid was contacted at 230℃ and pH 3 for 72 hours to evaluate its corrosion inhibition performance on P110 carbon steel. The evaluation results of the purine-based Mannich base corrosion inhibitor and commercially available Mannich base corrosion inhibitor at different dosages are shown in Table 6.

[0085] Table 6. Evaluation results of the corrosion inhibitor and commercially available Mannich base corrosion inhibitor in Example 6 at different dosages.

[0086]

[0087]

[0088] The foregoing description includes examples of one or more embodiments. It is certainly impossible to describe all possible combinations of components or methods in order to describe the above embodiments, but those skilled in the art will recognize that further combinations and arrangements of the various embodiments are possible. Therefore, the embodiments described herein are intended to cover all such changes, modifications, and variations that fall within the scope of the appended claims. Furthermore, the term "comprising" as used in the specification or claims is interpreted in a manner similar to the term "including," just as "comprising" is interpreted as a conjunction in the claims. Additionally, the use of any term "or" in the specification of the claims is intended to mean "non-exclusive or."

Claims

1. A purine-based Mannich base corrosion inhibitor, characterized in that, The structural formula of the purine-based Mannich base corrosion inhibitor is shown in formula (Ⅰ): Where R1 is H or n＝0～2； R2 is 2. The method for preparing the purine-based Mannich base corrosion inhibitor according to claim 1, characterized in that, include: Aldehydes, ketones and purines are added to methanol, mixed thoroughly and dissolved, and then concentrated hydrochloric acid is added to the reaction system to adjust the pH of the reaction system to 1-4 to carry out the Mannich reaction. After the Mannich reaction is completed, the reaction system is cooled to room temperature, the solvent in the system is removed, recrystallized and filtered to obtain a purine-based Mannich base corrosion inhibitor.

3. The method according to claim 2, characterized in that, The molar ratio of the aldehyde, ketone and purine is (1.2-1.5):(1.1-1.2):

1.

4. The method according to claim 2, characterized in that, The Mannich reaction is carried out at a temperature of 85–95°C for a reaction time of 6–12 hours.

5. The method according to claim 2, characterized in that, The aldehydes include any one or more of formaldehyde, acetaldehyde, and phenylacetaldehyde.

6. The method according to claim 2, characterized in that, The ketones include any one or more of acetone, cyclohexanone, and acetophenone.

7. The application of the purine-based Mannich base corrosion inhibitor as described in claim 1 in well completion fluid.

8. A completion fluid, characterized in that, Includes the purine-based Mannich base corrosion inhibitor as described in claim 1.

9. The completion fluid according to claim 8, characterized in that, The mass percentage of the purine-based Mannich base corrosion inhibitor is 1% to 10% based on the mass of the completion fluid.

10. The application of the completion fluid according to any one of claims 8 to 9 in oilfield completion operations.

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