Corrosion and scale inhibition integrated agent for CO2 flooding production system as well as preparation method and application of corrosion and scale inhibition integrated agent

Abstract

The invention discloses a corrosion and scale inhibition integrated agent. The corrosion and scale inhibition integrated agent comprises effective components with the following chemical structural formula. The invention further discloses a preparation method and application of the corrosion and scale inhibition integrated agent. The integrated agent can be applied to oil and gas well development, is particularly suitable for corrosion prevention and scale inhibition of a production system of a technology for improving oil and gas recovery ratio (CO2-EOR) by carbon dioxide (CO2) gas drive, can solve the antagonism effect of a compound corrosion inhibitor and a scale inhibitor, effectively controls the corrosion and scaling problems of a shaft and a gathering and transportation pipeline in the CO2 oil displacement process, and improves the oil and gas recovery ratio. The corrosion and scale inhibitor has excellent corrosion and scale inhibition effects.

Description

Technical Field

[0001] This invention relates to the field of oilfield chemical technology, specifically to an integrated corrosion and scale inhibitor for CO2 flooding production systems, its preparation method, and its application. Background Technology

[0002] Carbon Capture, Utilization and Storage (CCUS) technology is an internationally recognized large-scale direct emission reduction technology. It is also an important technological tool that can significantly improve the recovery rate of old oilfields and effectively develop low-permeability and ultra-low-permeability reservoirs. It is widely used in countries such as the United States and Canada. In my country, industrial-scale trials have also been carried out in Jilin Oilfield, Shengli Oilfield, Daqing Oilfield and other places, and good carbon sequestration and oil displacement production enhancement effects have been achieved. Therefore, it has broad application prospects.

[0003] However, the application of CO2-EOR technology may create corrosive environments such as high temperature and pressure, and supercritical CO2, causing severe corrosion damage to extraction facilities. CO2 corrosive environments typically form during CO2-containing oil and gas extraction, or in processes such as carbon capture and storage (CCS) and CO2-EOR. As a weak acid, carbonic acid only partially dissociates in aqueous solution; therefore, CO2 solutions cause more severe corrosion problems than strong acid solutions of the same acidity. In CO2-EOR processes for deep oil wells, the CO2 state is maintained above the critical point (73.8 bar, 31.1℃), and the resulting supercritical CO2 corrosive environment causes several times more severe damage to production equipment than conventional CO2 environments. Many corrosion inhibitors and scale inhibitors effective in non-supercritical CO2 environments show significant performance degradation or even failure in supercritical CO2 environments. Therefore, researching efficient corrosion inhibitors and scale inhibitors for supercritical CO2 environments is of great significance for oilfield development.

[0004] Most commonly used corrosion and scale inhibitors are compounded from inorganic salts, organic amines, and organophosphorus compounds. They are suitable for neutral environments with a single corrosive medium, but cannot effectively inhibit CO2 corrosion and scaling. Currently, for the corrosion and scaling problems faced by carbon steel pipelines in CO2 flooding processes, corrosion and scale inhibitors are mostly compounded from corrosion inhibitors and scale inhibitors. However, directly mixing corrosion inhibitors and scale inhibitors can produce antagonistic effects, leading to incompatibility problems such as flocculation and precipitation, which seriously affects the corrosion and scale inhibition effects of both agents.

[0005] Therefore, in the current CO2 flooding process, especially under the condition that the CO2 state will be maintained above the critical point (73.8 bar, 31.1℃), the development of efficient integrated corrosion and scale inhibitors is of great significance for oilfield development. Summary of the Invention

[0006] To address the aforementioned deficiencies or improvement needs of existing technologies, this invention provides an integrated corrosion and scale inhibitor, its preparation method, and its application. This integrated corrosion and scale inhibitor incorporates both corrosion-inhibiting and scale-inhibiting groups into one molecule, resulting in an integrated agent with both corrosion-inhibiting and scale-inhibiting effects. This avoids the potential antagonistic effects that may occur when corrosion inhibitors and scale inhibitors are combined, achieving a dual-effect effect with a single agent. Furthermore, this integrated corrosion and scale inhibitor can be applied in the oil and gas extraction field.

[0007] To achieve the above objectives, a first aspect of the present invention provides an integrated corrosion and scale inhibitor, wherein the integrated corrosion and scale inhibitor comprises an effective component having the following chemical structural formula:

[0008]

[0009] On the other hand, the present invention provides a method for preparing an integrated corrosion and scale inhibitor, comprising the following steps:

[0010] Thiourea-based oleic acid imidazoline (OA-IM-TU) and hydroxyethylidene diphosphonic acid (HEDP) were subjected to a dehydration reaction in a solvent, heated and stirred, and the solvent was removed after the reaction was completed to obtain an integrated corrosion and scale inhibitor of thiourea-based oleic acid imidazoline phosphonic acid (OA-IM-TU-HEDP).

[0011] The solvent is at least one of ethanol and methanol;

[0012] The heating and stirring are performed at a temperature between 80°C and 100°C, preferably at 90°C.

[0013] Furthermore, the molar ratio of thiourea-oleic acid imidazoline (OA-IM-TU) to hydroxyethylidene diphosphonic acid (HEDP) is 1:(0.8-1.2), preferably 1:1.

[0014] Furthermore, the heating and stirring time is 1 to 3 hours, preferably 2 hours.

[0015] Furthermore, the dehydration reaction of the thiourea-oleic acid imidazoline (OA-IM-TU) and hydroxyethylidene diphosphonic acid (HEDP) in a solvent is as follows:

[0016]

[0017] In another embodiment, the thiourea-oleic acid imidazoline (OA-IM-TU) is prepared by a deamination reaction of oleic acid imidazoline (OA-IM) and thiourea (TU);

[0018] The molar ratio of oleic acid imidazoline to thiourea is 1:(0.8-1.2), preferably 1:1.

[0019] The temperature of the deamination reaction is 130-150℃, preferably 140℃.

[0020] Furthermore, the deamination reaction time is 1 to 3 hours, preferably 2 hours.

[0021] In another embodiment, the oleic acid imidazoline (OA-IM) is synthesized from oleic acid and diethylenetriamine using a solvent method.

[0022] Furthermore, the solvent synthesis operation involves dissolving oleic acid in a solvent / water-carrying agent, adding a catalyst, then adding diethylenetriamine dropwise, heating and stirring to carry out an amidation dehydration reaction. After the reaction is completed, the temperature is raised to carry out a cyclization dehydration reaction. The product after the reaction is subjected to vacuum distillation to remove the solvent, thereby obtaining oleic acid imidazoline (OA-IM).

[0023] Furthermore, the solvent / water-carrying agent is xylene, and the catalyst is NH4Cl;

[0024] The molar ratio of oleic acid to diethylenetriamine is 1:1.2.

[0025] In another embodiment, the present invention also provides an application of an integrated corrosion and scale inhibitor, which is applied to carbon dioxide (CO2) gas-driven enhanced oil and gas recovery (CO2-EOR) technology.

[0026] The application of the aforementioned integrated corrosion and scale inhibitor involves adding it at a concentration of 50–250 ppm, preferably 200 ppm.

[0027] Compared with the prior art, the present invention provides a single-molecule integrated corrosion and scale inhibitor. This reagent is suitable for oil and gas field development, especially for corrosion and scale prevention in CO2 flooding production systems. It can solve the antagonistic effect of compound corrosion inhibitors and scale inhibitors, and has excellent corrosion and scale inhibition effects. Attached Figure Description

[0028] Figure 1 The reaction formula for the synthesis process in the embodiments of the present invention;

[0029] Figure 2 Infrared spectrum of thiourea-based oleic acid imidazoline phosphonic acid corrosion and scale inhibitor;

[0030] Figure 3 Example 3 tested the corrosion inhibition performance of N80 carbon steel in CO2-saturated formation water containing different concentrations of OA-IM-TU-HEDP corrosion and scale inhibitors.

[0031] Among them, 3(a) is the EIS electrochemical impedance spectrum; 3(b) is the polarization curve;

[0032] Figure 4 The equivalent circuit fitted to EIS;

[0033] Of these, 4(a) is in the blank case, and 4(b) is in the case containing corrosion inhibitor;

[0034] Figure 5 Comparison of corrosion inhibition properties of thiourea-based oleic acid imidazoline (OA-IM-TU), oleic acid imidazoline, and thiourea compound (OA-IM+TU);

[0035] Among them, 5(a) is the EIS electrochemical impedance spectroscopy, and 5(b) is the polarization curve;

[0036] Figure 6 Comparison of corrosion inhibition performance between thiourea-oleic acid imidazoline phosphonic acid corrosion and scale inhibitor (OA-IM-TU-HEDP) and thiourea-oleic acid imidazoline and HEDP compound (OA-IM-TU+HEDP);

[0037] Among them, 6(a) EIS electrochemical impedance spectroscopy, 6(b) polarization curve;

[0038] Figure 7 The corrosion rate and corrosion inhibition efficiency of N80 carbon steel in formation water blank solution and with different concentrations of OA-IM-TU-HEDP corrosion and scale inhibitor were determined under the conditions of 120℃, 0.5m / s, and 8MPa CO2.

[0039] Figure 8 The macroscopic morphology of N80 carbon steel after corrosion in formation water blank solution and after adding different concentrations of OA-IM-TU-HEDP corrosion inhibitor under the conditions of 120℃, 0.5m / s, and 8MPa CO2 is shown.

[0040] Figure 9 The SEM microstructures of N80 carbon steel after corrosion in formation water blank solution and with different concentrations of OA-IM-TU-HEDP corrosion inhibitor under the conditions of 120℃, 0.5m / s, and 8MPa CO2 are as follows: (a,b,c) blank, (d,e,f) 50ppm, (g,h,i) 100ppm, (j,k,l) ​​150ppm, (m,n,o) 200ppm, (p,q,r) 250ppm;

[0041] Figure 10 The results show the scale inhibition performance of different concentrations of OA-IM-TU-HEDP corrosion and scale inhibitor. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0043] Example 1

[0044] The preparation process of the integrated corrosion and scale inhibitor provided by the present invention includes the following steps:

[0045] 1) Oleic acid imidazoline was synthesized via a solvent method using oleic acid and diethylenetriamine as raw materials. First, 0.1 mol of oleic acid was added to a three-necked round-bottom flask connected to an external water separator. 50 mL of xylene was added as a solvent and water-carrying agent, followed by 1% NH₄Cl as a catalyst. Then, 0.12 mol of diethylenetriamine was added dropwise, and the mixture was heated and stirred at 135 °C for an amidation dehydration reaction for 4 h. The temperature was then raised to 200 °C for a cyclization dehydration reaction for 4 h. After the reaction, the product was subjected to vacuum distillation to remove the xylene solvent, yielding oleic acid imidazoline (OA-IM).

[0046] 2) Add 0.1 mol of oleic acid imidazoline and 0.1 mol of thiourea in a molar ratio of 1:1 to a round-bottom flask, heat and stir, and carry out the deamination reaction at 140℃ for 2 h to obtain thiourea-oleic acid imidazoline (OA-IM-TU).

[0047] 3) Add 0.1 mol of thiourea-oleic acid imidazoline and 0.1 mol of hydroxyethylidene diphosphonic acid (HEDP) in a round-bottom flask at a molar ratio of 1:1, add 10 mL of ethanol as solvent, heat and stir, and carry out dehydration reaction at 70℃, 80℃, 90℃ and 100℃ for 2 h respectively. Remove the ethanol solvent by rotary evaporation of the product after reaction to obtain thiourea-oleic acid imidazoline phosphonic acid corrosion and scale inhibitor (OA-IM-TU-HEDP).

[0048] The synthesis route of the thiourea-based oleic acid imidazoline phosphonic acid corrosion and scale inhibitor (OA-IM-TU-HEDP) is as follows: Figure 1 The yields of the thiourea-based oleic acid imidazoline phosphonic acid corrosion and scale inhibitor (OA-IM-TU-HEDP) obtained at 70℃, 80℃, 90℃, and 100℃ were 40.3%, 78.2%, 87.3%, and 87.8%, respectively. It can be seen that a relatively high yield of the target product can be obtained above 80℃, while the yield is relatively low under dehydration conditions at 70℃, making it unsuitable for industrial production. Furthermore, the yield did not significantly increase when the temperature increased from 90℃ to 100℃. Considering energy conservation, the preferred reaction temperature is 90℃.

[0049] Example 2

[0050] The preparation process of the integrated corrosion and scale inhibitor provided by the present invention includes the following steps:

[0051] 1) Oleic acid imidazoline was synthesized via a solvent method using oleic acid and diethylenetriamine as raw materials. First, 0.1 mol of oleic acid was added to a three-necked round-bottom flask connected to an external water separator. 50 mL of xylene was added as a solvent and water-carrying agent, followed by 1% NH₄Cl as a catalyst. Then, 0.12 mol of diethylenetriamine was added dropwise, and the mixture was heated and stirred at 135 °C for an amidation dehydration reaction for 4 h. The temperature was then raised to 200 °C for a cyclization dehydration reaction for 4 h. After the reaction, the product was subjected to vacuum distillation to remove the xylene solvent, yielding oleic acid imidazoline (OA-IM).

[0052] 2) Add 0.1 mol of oleic acid imidazoline and 0.1 mol of thiourea in a molar ratio of 1:1 to a round-bottom flask, heat and stir, and carry out the deamination reaction at 140℃ for 2 h to obtain thiourea-oleic acid imidazoline (OA-IM-TU).

[0053] 3) 0.1 mol of thiourea-oleic acid imidazoline and 0.07 mol, 0.08 mol, 0.1 mol, 0.12 mol, and 0.15 mol of hydroxyethylidene diphosphonic acid (HEDP) were added to round-bottom flasks at molar ratios of 1:0.7, 1:0.8, 1:1, 1:1.2, and 1:1.5, respectively. 10 mL of ethanol was added as a solvent, and the mixture was heated and stirred. The dehydration reaction was carried out at 90 °C for 2 h. The product after the reaction was removed by rotary evaporation to obtain thiourea-oleic acid imidazoline phosphonic acid corrosion and scale inhibitor (OA-IM-TU-HEDP). The yields of thiourea-oleic acid imidazoline and hydroxyethylidene diphosphonic acid (HEDP) corrosion and scale inhibitors (OA-IM-TU-HEDP) obtained by molar ratios of 1:0.7, 1:0.8, 1:1, 1:1.2, and 1:1.5 were 57.4%, 82.4%, 87.3%, 87.1%, and 61.8%, respectively. The yields were lower at molar ratios of 1:0.7 or 1:1.5, while the yields were better in production at molar ratios of 1:0.8-1:1.2. The preferred molar ratio of thiourea-oleic acid imidazoline and hydroxyethylidene diphosphonic acid (HEDP) was 1:1.

[0054] Example 3

[0055] The preparation process of the integrated corrosion and scale inhibitor provided by the present invention includes the following steps:

[0056] 1) Oleic acid imidazoline was synthesized via a solvent method using oleic acid and diethylenetriamine as raw materials. First, 0.1 mol of oleic acid was added to a three-necked round-bottom flask connected to an external water separator. 50 mL of xylene was added as a solvent and water-carrying agent, followed by 1% NH₄Cl as a catalyst. Then, 0.12 mol of diethylenetriamine was added dropwise, and the mixture was heated and stirred at 135 °C for an amidation dehydration reaction for 4 h. The temperature was then raised to 200 °C for a cyclization dehydration reaction for 4 h. After the reaction, the product was subjected to vacuum distillation to remove the xylene solvent, yielding oleic acid imidazoline (OA-IM).

[0057] 2) Add 0.1 mol of oleic acid imidazoline and 0.1 mol of thiourea in a molar ratio of 1:1 to a round-bottom flask, heat and stir, and carry out the deamination reaction at 140℃ for 2 h to obtain thiourea-oleic acid imidazoline (OA-IM-TU).

[0058] 3) 0.1 mol of thiourea-oleic acid imidazoline and 0.1 mol of hydroxyethylidene diphosphonic acid (HEDP) were added to a round-bottom flask at a molar ratio of 1:1. 10 mL of ethanol was added as a solvent, and the mixture was heated and stirred. Dehydration reactions were carried out at 90 °C for 0.5 h, 1 h, 2 h, 3 h, and 4 h, respectively. The ethanol solvent was removed by rotary evaporation of the reaction product to obtain the thiourea-oleic acid imidazoline phosphonic acid corrosion and scale inhibitor (OA-IM-TU-HEDP). The yields of the thiourea-oleic acid imidazoline phosphonic acid corrosion and scale inhibitor (OA-IM-TU-HEDP) obtained after 0.5 h, 1 h, 2 h, 3 h, and 4 h of reaction were 32.1%, 79.5%, 87.3%, 87.9%, and 88.1%, respectively. During the reaction, the reaction was incomplete at 0.5 h, but almost complete after 1 h, with a yield reaching 80%. However, when the reaction was extended further to 4 h, the yield did not significantly increase. Considering the reaction time cost, the preferred reaction time is 2 hours.

[0059] Example 4

[0060] The preparation process of the integrated corrosion and scale inhibitor provided by this invention includes the following steps:

[0061] 1) Oleic acid imidazoline was synthesized via a solvent method using oleic acid and diethylenetriamine as raw materials. First, 0.1 mol of oleic acid was added to a three-necked round-bottom flask connected to an external water separator. 50 mL of xylene was added as a solvent and water-carrying agent, followed by 1% NH₄Cl as a catalyst. Then, 0.12 mol of diethylenetriamine was added dropwise, and the mixture was heated and stirred at 135 °C for an amidation dehydration reaction for 4 h. The temperature was then raised to 200 °C for a cyclization dehydration reaction for 4 h. After the reaction, the product was subjected to vacuum distillation to remove the xylene solvent, yielding oleic acid imidazoline (OA-IM).

[0062] 2) Add 0.1 mol of oleic acid imidazoline and 0.1 mol of thiourea in a molar ratio of 1:1 to a round-bottom flask, heat and stir, and carry out the deamination reaction at 140℃ for 2 h to obtain thiourea-oleic acid imidazoline (OA-IM-TU).

[0063] 3) 0.1 mol of thiourea-oleic acid imidazoline and 0.1 mol of hydroxyethylidene diphosphonic acid (HEDP) were added to a round-bottom flask at a molar ratio of 1:1. 10 mL of ethanol was added as a solvent, and the mixture was heated and stirred. The dehydration reaction was carried out at 90 °C for 2 h. The product after the reaction was removed by rotary evaporation to remove the ethanol solvent, and thiourea-oleic acid imidazoline phosphonic acid corrosion and scale inhibitor (OA-IM-TU-HEDP) was obtained with a yield of 87.3%.

[0064] Example 5

[0065] Infrared spectroscopy was performed on the thiourea-based oleic acid imidazoline phosphonic acid corrosion and scale inhibitor (OA-IM-TU-HEDP) prepared in Example 4. The test results are shown in [reference needed]. Figure 2 Among them, oleic acid imidazoline (OA-IM) has an infrared spectrum at 2918 cm⁻¹. -1 2854cm to its right -1 The extraction peaks are absorption peaks of the asymmetric and symmetric stretching vibrations of -CH2-, at 1600 cm⁻¹. -1 The characteristic absorption peak at C=N of the imidazoline ring at 2106 cm⁻¹ confirms the successful synthesis of imidazoline oleate. Thiourea (TU) shows a peak at 2106 cm⁻¹. -1 and 2032cm -1 Two characteristic peaks are present at 2053 cm⁻¹. After the reaction of oleic acid imidazoline with thiourea, thiourea-oleic acid imidazoline (OA-IM-TU) exhibits a peak at 2053 cm⁻¹. -1 The appearance of a strong peak at 923 cm⁻¹ indicates a shift in the infrared peak position of the C=S double bond, confirming the deamination reaction between thiourea and imidazoline to generate thiourea-oleic acid imidazoline. The infrared spectrum of thiourea-oleic acid imidazoline phosphonic acid (OA-IM-TU-HEDP) shows a peak at 923 cm⁻¹. -1 The peak at this location is a characteristic peak of PNC, indicating that the phosphonic acid group was successfully attached to the thiourea-oleic acid imidazoline. Infrared spectroscopy analysis shows that the synthesized product is the target product.

[0066] Example 6

[0067] The corrosion inhibition performance of the thiourea-based oleic acid imidazoline phosphonic acid corrosion and scale inhibitor (OA-IM-TU-HEDP) prepared in Example 4 on carbon steel was analyzed by electrochemical impedance spectroscopy (EIS) and polarization curve testing. The test material was N80 carbon steel, and the medium was simulated formation water from an oilfield, the composition of which is shown in Table 1. The test temperature was 60℃, and the CO2 pressure was 0.1 MPa.

[0068] Table 1. Simulated formation water composition (mg / L) in the oilfield

[0069] <![CDATA[Na + ]]> <![CDATA[Mg 2+ ]]> <![CDATA[Ca 2+ ]]> <![CDATA[Cl - ]]> <![CDATA[SO4 2- ]]> <![CDATA[HCO3 - ]]> <![CDATA[CO3 2- ]]> TDS 1450 3 10 1650 57 969 10.8 4149.8

[0070] Test results are available Figure 3 Figure 3(a) shows the EIS electrochemical impedance spectroscopy; Figure 3(b) shows the polarization curve. Figure 3 Figure a shows the Nyquist impedance diagrams in CO2-saturated formation water at 60℃ with and without OA-IM-TU-HEDP corrosion and scale inhibitor. The figure shows that the Nyquist diagram in the blank solution exhibits a slightly flattened semicircle, which may be related to the rough surface formed after corrosion of the carbon steel. However, after adding OA-IM-TU-HEDP corrosion and scale inhibitor, the capacitive arc semicircle significantly increases, indicating that OA-IM-TU-HEDP has excellent corrosion inhibition performance. Furthermore, the diameter of the capacitive arc increases with increasing OA-IM-TU-HEDP concentration, indicating that increasing the concentration of OA-IM-TU-HEDP allows the carbon steel surface to adsorb more OA-IM-TU-HEDP, thus more effectively inhibiting carbon steel corrosion.

[0071] use Figure 4 The equivalent circuit was used to fit the EIS data to obtain the relevant electrochemical parameter values, where R s R is the resistance of the solution. ct For charge transfer resistance, Q dl Q is a constant phase angle element representing the double-layer capacitance between the electrode and the solution. f and R f These represent the capacitance and resistance of the film containing the adsorbed corrosion inhibitor.

[0072] Table 2 presents the EIS fitting data. Among them, the polarization resistance R... p Equal to R f and R ct The sum. According to R p The corrosion inhibition efficiency of OA-IM-TU-HEDP corrosion and scale inhibitor at different concentrations can be calculated:

[0073]

[0074] Where R p and The polarization resistances were measured in the blank solution and the solution with added corrosion and scale inhibitors, respectively.

[0075] Table 2. EIS fitting data of carbon steel in CO2 saturated solutions containing different concentrations of OA-IM-TU-HEDP corrosion and scale inhibitors.

[0076]

[0077] Table 2 shows the R of carbon steel under blank conditions.p The value is 150Ωcm 2 The relatively low impedance indicates that carbon steel corrodes rapidly in CO2-saturated formation water without added corrosion inhibitors. However, R... (The sentence is incomplete and requires further context to translate accurately.) p The value increased significantly and increased with increasing concentration. After adding 100 ppm and 200 ppm, its R... p The values ​​are 9143 Ωcm 2 and 12701Ωcm 2 The value of R in the blank solution is much higher. p The values ​​correspond to corrosion inhibition efficiencies of 98.35% and 98.82%, respectively, indicating that OA-IM-TU-HEDP has excellent corrosion inhibition performance in CO2 corrosive environments.

[0078] The relevant parameters obtained by fitting the polarization curves are listed in Table 3. For example... Figure 3 As shown in b and Table 3, compared to the blank solution, the corrosion potential E of carbon steel after adding OA-IM-TU-HEDP corrosion and scale inhibitor was [value missing]. corr A significant positive shift was observed, but the positive potential shift value was less than 85mV, indicating that OA-IM-TU-HEDP is a hybrid corrosion inhibitor with a biased anodic nature, which has a more significant inhibitory effect on the anodic process of carbon steel corrosion.

[0079] Table 3. Polarization curve fitting parameters of carbon steel in CO2 saturated solutions containing different concentrations of OA-IM-TU-HEDP corrosion and scale inhibitors.

[0080]

[0081] Furthermore, compared to the blank solution, the addition of OA-IM-TU-HEDP corrosion and scale inhibitor shifted the polarization curves to a region with lower current densities. Both cathodic and anodic current densities decreased significantly, indicating that OA-IM-TU-HEDP simultaneously inhibited both anodic and cathodic processes, with a more significant inhibition of the anodic process, leading to a positive shift in corrosion potential. When 100 ppm and 200 ppm of OA-IM-TU-HEDP were added, the corrosion current density i... corr 1.44 × 10⁻⁶ ppm from the blank solution –4 A cm –2 Reduced to 2.13 × 10 –6 A cm –2 Or 1.86×10 –6 A cm –2 The corrosion inhibition efficiencies calculated using formula (2) were 98.5% and 98.7%, respectively, indicating that the synthesized OA-IM-TU-HEDP corrosion and scale inhibitor has excellent corrosion inhibition performance.

[0082]

[0083] in and i corr The corrosion current densities were measured in the blank solution and the solution with added corrosion and scale inhibitors, respectively.

[0084] Example 7

[0085] The corrosion inhibition effects of thiourea-based oleic acid imidazoline (OA-IM-TU) prepared in Example 4 and the composite of oleic acid imidazoline and thiourea (OA-IM+TU) were compared using EIS and polarization curve tests. The molar ratio of oleic acid imidazoline to thiourea was 1:1. The test results are shown in [reference needed]. Figure 5 As can be seen from the figure, the impedance spectrum of the compound with thiourea-based imidazoline oleate (OA-IM-TU) is greater than that of the compound with imidazoline oleate and thiourea, with corresponding impedance values ​​of 7471 Ωcm. 2 and 5804Ωcm 2 The corresponding corrosion inhibition efficiencies were 98.0% and 97.4%, respectively (Table 4). This indicates that the synthesized thiourea-based oleic acid imidazoline (OA-IM-TU) is not a combination of oleic acid imidazoline and thiourea, but rather that the thiourea group was successfully modified onto the oleic acid imidazoline molecule. Simultaneously, polarization curve tests also showed that the corrosion current density of thiourea-based oleic acid imidazoline (OA-IM-TU) was lower than that of the combination of oleic acid imidazoline and thiourea (Table 5), further demonstrating the successful synthesis of thiourea-based oleic acid imidazoline (OA-IM-TU).

[0086] Table 4. EIS fitting data of carbon steel in solutions of thiourea-based imidazoline oleate (OA-IM-TU), imidazoline oleate, and thiourea compound (OA-IM+TU).

[0087]

[0088] Table 5. Polarization curve fitting parameters for carbon steel in solutions of thiourea-based oleic acid imidazoline (OA-IM-TU), oleic acid imidazoline, and thiourea complex (OA-IM+TU).

[0089]

[0090] Example 8

[0091] The corrosion inhibition effects of the thiourea-oleic acid imidazoline phosphonic acid corrosion and scale inhibitor (OA-IM-TU-HEDP) prepared in Example 4 and the compound of thiourea-oleic acid imidazoline and HEDP (OA-IM-TU+HEDP) were compared using EIS and polarization curve tests. The molar ratio of OA-IM-TU and HEDP in the compound was 1:1. The results are as follows. Figure 6 As shown.

[0092] As can be seen from the figure, the impedance spectrum of the added thiourea-oleic acid imidazoline phosphonic acid corrosion and scale inhibitor (OA-IM-TU-HEDP) is greater than that of the combination of thiourea-oleic acid imidazoline and HEDP (OA-IM-TU+HEDP), with corresponding impedance values ​​of 9143 Ωcm. 2 and 6710Ωcm 2 The corresponding corrosion inhibition efficiencies were 98.3% and 97.8%, respectively (Table 6). This indicates that the synthesized thiourea-oleic acid imidazoline phosphonic acid corrosion and scale inhibitor (OA-IM-TU-HEDP) is not a combination of thiourea-oleic acid imidazoline and HEDP, but rather HEDP is successfully modified onto the thiourea-oleic acid imidazoline molecule to form an integrated corrosion and scale inhibitor. Simultaneously, polarization curve tests also show that the corrosion current density of the thiourea-oleic acid imidazoline phosphonic acid corrosion and scale inhibitor (OA-IM-TU-HEDP) is lower than that of the combination of thiourea-oleic acid imidazoline and HEDP (Table 7), further demonstrating the successful synthesis of the thiourea-oleic acid imidazoline phosphonic acid corrosion and scale inhibitor (OA-IM-TU-HEDP).

[0093] Table 6. EIS fitting data of carbon steel in solutions of thiourea-oleic acid imidazoline phosphonic acid corrosion and scale inhibitor (OA-IM-TU-HEDP) and thiourea-oleic acid imidazoline and HEDP compound (OA-IM-TU+HEDP).

[0094]

[0095] Table 7. Polarization curve fitting parameters of carbon steel in solutions of thiourea-oleic acid imidazoline phosphonic acid corrosion and scale inhibitor (OA-IM-TU-HEDP) and thiourea-oleic acid imidazoline and HEDP compound (OA-IM-TU+HEDP).

[0096]

[0097] Example 9

[0098] The corrosion inhibition performance of the OA-IM-TU-HEDP corrosion and scale inhibitor prepared in Example 4 was tested under high temperature and high pressure conditions. The corrosion rate and corrosion inhibition efficiency of N80 carbon steel in formation water blank solution and with different concentrations of OA-IM-TU-HEDP corrosion and scale inhibitor were tested using a high-temperature and high-pressure reactor at 120℃, 0.5 m / s, and 8 MPa CO2. The results are shown in [Figure number missing]. Figure 7 , Figure 8 and Figure 9 .

[0099] like Figure 7As shown in Table 8, the corrosion rate of carbon steel was relatively high under blank conditions, at 3.3256 mm / a. However, the corrosion rate of carbon steel decreased significantly after the addition of corrosion inhibitors, and the corrosion rate decreased with increasing OA-IM-TU-HEDP concentration. When 50 ppm of OA-IM-TU-HEDP was added, the corrosion rate was 0.8662 mm / a, corresponding to a corrosion inhibition efficiency of only 73.95%. When the concentration of the corrosion and scale inhibitor increased to 100 ppm, the corrosion rate decreased to 0.0916 mm / a, corresponding to a corrosion inhibition efficiency as high as 97.25%. With the concentration of the corrosion and scale inhibitor increasing to 200 ppm, the corrosion rate further decreased to 0.0663 mm / a, corresponding to a corrosion inhibition efficiency of 98.01%. When the concentration of the corrosion and scale inhibitor further increased to 250 ppm, the corrosion rate was 0.0723 mm / a, and the corresponding corrosion inhibition efficiency decreased slightly to 97.83%.

[0100] Table 8 shows the corrosion weight loss data of N80 carbon steel under conditions of 0.5 m / s, 120℃, 8 MPa CO2 formation water blank solution and solutions with different concentrations of OA-IM-TU-HEDP corrosion and scale inhibitor.

[0101]

[0102]

[0103] Figure 8 The macroscopic morphology of N80 carbon steel under formation water conditions of 120℃, 0.5 m / s, and 8 MPa CO2, before and after the removal of corrosion products, is shown. The figures show that under the blank condition, a large amount of corrosion products formed on the surface of the carbon steel, indicating that the carbon steel underwent relatively severe corrosion in supercritical CO2 formation water. After removing the corrosion products, the corrosion morphology was observed to be mainly uniform corrosion, with no obvious localized corrosion. Even with the addition of 50 ppm of corrosion and scale inhibitor, some corrosion still occurred on the carbon steel surface, indicating that adding 50 ppm of corrosion and scale inhibitor was not very effective in inhibiting the corrosion of carbon steel. Further increasing the corrosion inhibitor concentration to over 100 ppm resulted in the adsorption of a layer of corrosion and scale inhibitor on the carbon steel surface. This adsorbed corrosion and scale inhibitor film prevented corrosive substances from contacting the carbon steel surface, thus effectively inhibiting the corrosion of the carbon steel, resulting in relatively mild corrosion.

[0104] Figure 9The SEM microstructures of N80 carbon steel surfaces after corrosion in formation water at 120℃, 0.5 m / s, and 8 MPa CO2 conditions, both in blank solution and after adding different concentrations of OA-IM-TU-HEDP corrosion and scale inhibitors, are shown. The figures reveal typical FeCO3 corrosion products on the surface of the carbon steel after corrosion under blank conditions. This further indicates that carbon steel undergoes severe corrosion in supercritical CO2 formation water. The relatively dense FeCO3 grain packing provides some protection against carbon steel corrosion. This is because, under the high temperature of 120℃, the solubility product of FeCO3 is relatively small, resulting in a lower concentration of Fe in the solution. 2+ Concentration and CO3 2- The product of concentrations easily exceeds the solubility product of FeCO3, resulting in the deposition of a relatively dense FeCO3 film on the carbon steel surface. After adding the corrosion and scale inhibitor, no FeCO3 film was observed on the carbon steel surface, indicating that the inhibitor effectively inhibited corrosion by adsorbing onto the carbon steel surface. 2+ The concentration decreased significantly, therefore the Fe in the solution 2+ Concentration and CO3 2- The concentration product is lower than the solubility product of FeCO3, so FeCO3 will not form a deposited film. Meanwhile, after adding the corrosion and scale inhibitor, the scratches from grinding on the surface of the carbon steel sample before corrosion are still clearly visible, indicating that the corrosion of the carbon steel is relatively mild after adding the corrosion and scale inhibitor. The OA-IM-TU-HEDP corrosion and scale inhibitor has superior corrosion inhibition performance.

[0105] Example 10

[0106] The scale inhibition performance of OA-IM-TU-HEDP corrosion and scale inhibitor on CaCO3 scale was tested according to the methods specified in the China National Petroleum Corporation enterprise standard Q / SY 126-2014 "Technical Specification for Corrosion and Scale Inhibitors for Oilfield Water Treatment". See the results below. Figure 10 And Table 9. Among them, Figure 10 The scale inhibition performance of different concentrations of OA-IM-TU-HEDP corrosion and scale inhibitor is presented. The figure shows that when the concentrations of OA-IM-TU-HEDP are 30 ppm, 60 ppm, and 100 ppm, the scale inhibition efficiencies (x) calculated using formula (3) are 90.83%, 91.04%, and 91.15%, respectively. Increasing the concentration of OA-IM-TU-HEDP corrosion and scale inhibitor does not significantly change the scale inhibition performance.

[0107]

[0108] In the formula:

[0109] —Calcium in the solution after adding scale inhibitor 2+ Concentration, in milligrams per liter (mg / L);

[0110] V 加样 —After adding scale inhibitor, titrate the solution for Ca. 2+ The concentration is expressed as the volume of EDTA standard solution consumed, in milliliters (mL).

[0111] —Ca in blank solution 1 2+ Concentration, in milligrams per liter (mg / L);

[0112] V 空白1 —Titration of Ca in blank solution 1 2+ The concentration is measured in milliliters (mL) of the volume of EDTA standard solution consumed.

[0113] —Ca in blank solution 2 2+ Concentration, in milligrams per liter (mg / L);

[0114] V 空白2 —Titration of Ca in blank solution 2 2+ The concentration is expressed as the volume of EDTA standard solution consumed, in milliliters (mL).

[0115] Table 9. Scale inhibition performance test results of different corrosion and scale inhibitors.

[0116]

[0117] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims and their equivalents, this invention also intends to include these modifications and variations. The above-described embodiments are merely preferred embodiments for fully illustrating the invention, and their scope of protection is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on this invention are all within the scope of protection of this invention, which is defined by the claims.

Claims

1. An integrated corrosion and scale inhibitor, characterized in that, The aforementioned integrated corrosion and scale inhibitor includes an effective component having the following chemical structural formula:

2. A corrosion and scale inhibitor as described in claim 1, characterized in that, The active ingredients of the integrated corrosion and scale inhibitor are prepared by dehydration reaction of thiourea-oleic acid imidazoline and hydroxyethylidene diphosphonic acid in a solvent.

3. A method for preparing the integrated corrosion and scale inhibitor as described in any one of claims 1-2, characterized in that, The preparation method includes the following steps: Thiourea-based oleic acid imidazoline and hydroxyethylidene diphosphonic acid were dehydrated in a solvent, heated and stirred, and the solvent was removed after the reaction was completed to obtain an integrated corrosion and scale inhibitor of thiourea-based oleic acid imidazoline phosphonic acid. The solvent is at least one of ethanol and methanol.

4. The preparation method of the integrated corrosion and scale inhibitor as described in claim 3, characterized in that, The heating and stirring temperature is between 80 and 100°C.

5. The preparation method of the integrated corrosion and scale inhibitor as described in claim 3, characterized in that, The molar ratio of the thiourea-oleic acid imidazoline and hydroxyethylidene diphosphonic acid is 1:(0.8-1.2).

6. The preparation method of the integrated corrosion and scale inhibitor as described in claim 3, characterized in that, The heating and stirring time is 1 hour to 3 hours.

7. The preparation method of the integrated corrosion and scale inhibitor as described in claim 3, characterized in that, The thiourea-based oleic acid imidazoline is prepared by a deamination reaction of oleic acid imidazoline and thiourea. The molar ratio of oleic acid imidazoline to thiourea is 1:(0.8-1.2). The temperature of the deamination reaction is between 130 and 150°C. The deamination reaction time is 1 to 3 hours.

8. The preparation method of the integrated corrosion and scale inhibitor as described in claim 3, characterized in that, The oleic acid imidazoline is synthesized from oleic acid and diethylenetriamine using a solvent method. The solvent synthesis operation involves dissolving oleic acid in a solvent / water-carrying agent, adding a catalyst, then adding diethylenetriamine dropwise, heating and stirring to carry out an amidation dehydration reaction. After the reaction is completed, the temperature is raised to carry out a cyclization dehydration reaction. The product after the reaction is subjected to vacuum distillation to remove the solvent, thereby obtaining oleic acid imidazoline.

9. The preparation method of the integrated corrosion and scale inhibitor as described in claim 8, characterized in that, The solvent / water-carrying agent is xylene; the catalyst is NH4Cl.

10. The application of the integrated corrosion and scale inhibitor as described in any one of claims 1-2 or the integrated corrosion and scale inhibitor prepared according to any one of claims 3-9 in a CO2 drive production system.

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