Benzimidazolyl surfactant as well as preparation and application thereof

Abstract

The invention discloses a benzimidazolyl surfactant and preparation and application thereof, the chemical structural formula of the benzimidazolyl surfactant is shown in the specification, n is 10-30, and m is 0-30. The invention provides a method for preparing a benzimidazolyl surfactant, which comprises the following steps: reacting o-phenylenediamine with cinnamyl aldehyde to synthesize styryl benzimidazole, carrying out ring-opening reaction on the styryl benzimidazole and epoxypropane to obtain an intermediate, and carrying out ring-opening reaction on the intermediate and ethylene oxide to prepare the benzimidazolyl surfactant. The synthesis mode has the characteristics of environmental friendliness and simple synthesis method. The benzimidazolyl surfactant prepared by the invention is a thick oil viscosity reducer with a relatively good viscosity reduction effect, has a relatively good corrosion inhibition effect in simulated seawater, is good in stability, small in stratum adsorption and low in damage, and is suitable for oil exploitation. # imgabs0 #

Description

Technical Field

[0001] The invention relates to a surfactant and its preparation and application, in particular to a benzimidazole-based surfactant and its preparation and application in corrosion inhibition and viscosity reduction in oilfield chemistry. Background Art

[0002] Heavy oil is an important oil resource in the world. With the increasing depletion of conventional oil resources, heavy oil has great development potential in energy supply. Heavy oil reservoirs are buried deep, and the viscosity of heavy oil under reservoir conditions ranges from 70 to 50,000 mPa·s. In the process of offshore heavy oil development, electric submersible pump cold production and thermal stimulation methods are commonly used. However, the viscosity of heavy oil will increase significantly with the increase of water content, especially under the influence of the high viscosity of water-in-oil (W / O) emulsions, resulting in decreased formation fluidity and reduced heavy oil production, which in turn affects the recovery rate. Therefore, reducing the viscosity of heavy oil and improving its fluidity are the key to solving the problem of heavy oil development.

[0003] Commonly used methods for reducing the viscosity of heavy oil can be divided into physical methods and chemical methods. Physical viscosity reduction methods include dilution method (by adding light hydrocarbons to the oil system) and heating method (reducing the viscosity of crude oil by heating the pipeline during transportation). However, physical methods usually have the disadvantages of high cost and high energy consumption. In contrast, chemical viscosity reduction methods can avoid these shortcomings by adding chemical reagents to heavy oil. Chemical reagents mainly include oil-soluble agents, nanoparticles and emulsifiers, but the oil-soluble agent method and nanoparticle method are difficult to be widely commercialized due to their high cost. The emulsification method is widely used in heavy oil viscosity reduction because of its simplicity and high efficiency. In particular, the widespread use of amphiphilic polymers (i.e., surfactants) in recent years has further improved the viscosity reduction effect. This type of polymer has the characteristics of being both hydrophilic and lipophilic, and exhibits excellent emulsification viscosity reduction effects.

[0004] Developing a benzimidazole-based surfactant that has both equipment corrosion inhibition and crude oil viscosity reduction functions can effectively improve mining efficiency, protect equipment, reduce production costs, and reduce environmental burden, which has become a technical problem that needs to be solved urgently. Summary of the invention

[0005] Purpose of the invention: The purpose of the present invention is to provide a benzimidazole-based surfactant that has both equipment corrosion inhibition and crude oil viscosity reduction functions. Another purpose of the present invention is to provide a method for preparing a benzimidazole-based surfactant, thereby solving the problem of how to prepare a benzimidazole-based surfactant. The third aspect of the present invention discloses the use of the above-mentioned benzimidazole-based surfactant in metal corrosion inhibition and heavy oil viscosity reduction, thereby solving the problem of how to obtain a heavy oil viscosity reducer and / or a metal slow-release agent.

[0006] Technical solution: The benzimidazole-based surfactant described in the present invention has the following chemical structural formula:

[0007]

[0008] Among them, n is 10-30, and m is 0-30.

[0009] Preferably, n is 15-25 and m is 10-30.

[0010] Preferably, n is 18, 20 or 22, and m is 23, 25 or 27.

[0011] Another aspect of the present invention discloses a method for preparing the above-mentioned benzimidazole-based surfactant, comprising the following steps:

[0012]

[0013] Preferably, the base is a strong inorganic base, the reaction conditions are 100-120° C. for 0.5-1 h under vacuum, and the molar ratio of the compound II to ethylene oxide is 10-30:1-30, preferably 15-25:20-30.

[0014] Preferably, the preparation method of compound II is:

[0015]

[0016] Preferably, the base is a strong inorganic base, the reaction conditions are 100-120° C. for 0.5-1 h under vacuum, and the molar ratio of the compound III to propylene oxide is 1:10-30.

[0017] Preferably, the preparation method of compound III is:

[0018]

[0019] Preferably, the molar ratio of compound IV to compound V is 1-3:1-3, the catalyst is boric acid, and the reaction conditions are 40-80° C. for 2-8 hours.

[0020] The third aspect of the present invention discloses the use of the benzimidazole-based surfactant in metal corrosion inhibition and heavy oil viscosity reduction.

[0021] In some embodiments, the benzimidazole-based surfactant is mixed with water at a mass percentage concentration of 500-1000 ppm and used as a heavy oil viscosity reducer and / or a metal slow-release agent.

[0022] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:

[0023] 1. The present invention provides a method for preparing a benzimidazole-based surfactant (VR) by reacting o-phenylenediamine with cinnamaldehyde to synthesize styrylbenzimidazole, then performing a ring-opening reaction with propylene oxide to obtain an intermediate, and then performing a ring-opening reaction with ethylene oxide. The synthesis method is environmentally friendly and simple.

[0024] 2. The benzimidazole-based surfactant (VR) prepared by the present invention is a heavy oil viscosity reducer with good viscosity reduction effect, and has good corrosion inhibition effect in simulated seawater. In the simulated seawater environment, 500ppm VR has a corrosion inhibition efficiency of up to 75.68% for carbon steel #20. At the same time, after being kept at 50°C for 2 hours, the viscosity reduction rate of the surfactant for crude oil reaches 88.59%, which meets the national petroleum and natural gas industry standards. While reducing the viscosity, it protects equipment and saves crude oil recovery costs. It has good stability, low adsorption to formations, and low damage, and is suitable for oil production. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A schematic diagram of the viscoelasticity curve of crude oil reduced by the benzimidazole-based surfactant (VR-2) prepared in Example 2;

[0026] Figure 2 Schematic diagram of apparent viscosity and viscosity reduction rate of benzimidazole-based surfactant (VR-2) prepared in Example 2 after mixing with heavy oil;

[0027] Figure 3 This is a graph showing the natural sedimentation dehydration rate of the benzimidazole-based surfactant (VR-2) prepared in Example 2 and the heavy oil emulsion;

[0028] Figure 4 Schematic diagram of the surface tension curves of the present invention (VR-1, VR-2 and VR-3);

[0029] Figure 5 This is a graph showing the corrosion inhibition effect of the present invention (VR-1, VR-2 and VR-3) on carbon steel #20. DETAILED DESCRIPTION

[0030] The technical solution of the present invention is further described below in conjunction with the accompanying drawings.

[0031] Example 1: A benzimidazole-based surfactant, the chemical structure of which is as follows:

[0032]

[0033] In this embodiment, n=18, m=23.

[0034] The preparation method of the benzimidazole-based surfactant comprises the following steps:

[0035] (1) In a polar solvent DMSO, o-phenylenediamine and cinnamaldehyde are mixed in an equal molar ratio, and boric acid is used as a catalyst. The temperature is heated to 40° C. and reacted for 8 h to synthesize styrylbenzimidazole. The solid product is precipitated by ice water bath, which is compound III. The reaction formula is as follows:

[0036]

[0037] (2) Compound III and KOH were added to a reactor at a molar ratio of 200:1, and propylene oxide was slowly added to react for 0.5 h under vacuum at a constant temperature of 110° C. to obtain an intermediate, namely compound II. The molar ratio of compound III to propylene oxide was 1:18, and the reaction formula was as follows:

[0038]

[0039] (3) Compound II and KOH were added to a reaction kettle at a molar ratio of 200:1, and ethylene oxide was slowly added to react for 0.5 h under vacuum at a constant temperature of 110° C. to obtain a benzimidazole-based surfactant VR-1. The molar ratio of compound II to ethylene oxide was 18:23, and the reaction formula was as follows:

[0040]

[0041] VR-1 was mixed and dissolved with water at a mass percentage concentration of 1000 ppm and used as a heavy oil viscosity reducer and metal slow-release agent.

[0042] Embodiment 2: The rest is the same as Embodiment 1, except that:

[0043] In the chemical structure, n=20, m=25;

[0044] In step (1), the molar ratio of o-phenylenediamine to cinnamaldehyde is 1:1.4, and the reaction is carried out at 55° C. for 5 hours;

[0045] In step (2), the molar ratio of compound III to KOH is 200:1, the molar ratio of compound III to propylene oxide is 1:20, and the reaction is carried out at 120° C. for 0.5 h;

[0046] In step (3), the molar ratio of compound II to KOH is 200:1, and the molar ratio of compound II to ethylene oxide is 20:25. The reaction is carried out at 120° C. for 0.5 h, and the final product is VR-2.

[0047] VR-1 was mixed and dissolved with water at a mass percentage concentration of 800 ppm and used as a heavy oil viscosity reducer and metal slow-release agent.

[0048] VR-2 was tested for viscoelasticity, and the viscoelasticity of crude oil without viscosity reducer and after adding VR-2 was determined. The oil used in the experiment was China South China Sea Oil. MCR302 rheometer was used, cc27 system was selected, the fixed angular frequency was 10rad / s, the scanning strain range was 0.3-100%, and the scanning rate increased logarithmically. The results are shown in Figure 1 As shown ( Figure 1 In the legend of the figure, G' is the storage modulus, G" is the loss modulus, and Oil represents crude oil). Figure 1 It can be seen that VR-2 can effectively reduce the viscoelasticity of crude oil.

[0049] VR-2 was tested for viscosity reduction of heavy oil. The effects of different VR-2 concentrations on viscosity reduction of heavy oil were compared in a constant temperature water bath at 50°C. The oil used in the experiment was China South China Sea Offshore Oil. After 1 hour of constant temperature, the stirring speed was 250r / min and stirred for 2 minutes. The apparent viscosity was measured using an MCR302 rheometer. The results are as follows: Figure 2 As shown in the figure, with the increase of VR-2 content, the viscosity of heavy oil decreased significantly and the viscosity reduction rate increased significantly, indicating that the viscosity reducer VR-2 has a good viscosity reduction effect.

[0050] VR-2 was tested for stability. Different concentrations of VR-2 were added to prepare 100 ml of heavy oil emulsion, added to a 100 ml stoppered measuring cylinder, and placed in a 50°C constant temperature water bath for 60 minutes. The natural sedimentation dehydration rate was calculated. The oil used in the experiment was China South China Sea Oil. The results are as follows: Figure 3 As shown in the figure, with the increase of VR-2 content, the dehydration rate increases. However, when the viscosity reducer concentration exceeds 1000ppm, the dehydration rate remains basically unchanged. The good dehydration rate shows that VR-2 can stabilize the emulsion.

[0051] Embodiment 3: The rest is the same as Embodiment 1, except that:

[0052] The rest are the same as in Example 1, except that:

[0053] In the chemical structure, n=22, m=27;

[0054] In step (1), the molar ratio of o-phenylenediamine to cinnamaldehyde is 2:1, and the reaction is carried out at 80° C. for 2 h;

[0055] In step (2), the molar ratio of compound III to KOH is 200:1, the molar ratio of compound III to propylene oxide is 1:22, and the reaction is carried out at 100° C. for 0.5 h;

[0056] In step (3), the molar ratio of compound II to KOH is 200:1, the molar ratio of compound II to ethylene oxide is 22:27, the reaction is carried out at 100° C. for 0.5 h, and the final product is VR-3.

[0057] VR-1 was mixed and dissolved with water at a mass percentage concentration of 500 ppm and used as a heavy oil viscosity reducer and metal slow-release agent.

[0058] The surface activity of the metal corrosion inhibition viscosity reducers VR-1, VR-2 and VR-3 prepared in Examples 1-3 was tested. The surface tension at different concentrations was measured using a JK99M6 fully automatic surface tension meter. The surface tension of solutions of different concentrations was tested by the hanging sheet method (Pt, width 24 mm). Each sample was measured three times and the average value was taken. The results are shown in Figure 4 As shown in the figure, it can be seen that the system has good surface activity. With the increase of concentration, the surface tension decreases and the surface activity increases, among which VR-2 shows better surface activity.

[0059] The corrosion inhibition performance of the metal corrosion inhibitors VR-1, VR-2 and VR-3 prepared in Examples 1-3 was tested. The surface of the #20 steel sheet sample was polished step by step with sandpaper, then degreased with acetone, rinsed with distilled water, dehydrated with anhydrous ethanol and weighed after drying. The corrosive medium used in the experiment was simulated seawater. At the set temperature of the experiment, the concentrations of the benzimidazole-based surfactants VR-1, VR-2 and VR-3 were fixed to be the same, and the treated steel sheets were immersed in the simulated seawater containing VR-1, VR-2 and VR-3 respectively, and corroded for 168 hours. After the samples were taken out, Figure 5 Cleaned with a brush, washed with deionized water and acetone, air-dried, re-weighed, the corrosion rate and corrosion inhibition efficiency were calculated from the weight loss of the sample, as shown in Table 1.

[0060] Table 1 Corrosion inhibition efficiency of benzimidazole-based surfactants (VR-1, VR-2 and VR-3) on carbon steel #20

[0061]

[0062] Depend on Figure 5 As shown in Table 1, at the same concentration, the benzimidazole-based surfactants all have good corrosion inhibition effects in simulated seawater, among which VR-2 is better.

Claims

1. A benzimidazole-based surfactant, characterized in that The chemical structure is as follows: Among them, n is 10-30, and m is 0-30.

2. The benzimidazole-based surfactant according to claim 1, characterized in that n is 15-25, and m is 10-30.

3. The benzimidazole-based surfactant according to claim 2, characterized in that: n is 18, 20 or 22, and m is 23, 25 or 27.

4. The method for preparing the benzimidazole-based surfactant according to any one of claims 1 to 3, characterized in that: The steps include:

5. The method for preparing the benzimidazole-based surfactant according to claim 4, characterized in that: The base is a strong inorganic base, the reaction conditions are 100-120° C. for 0.5-1 h under vacuum, and the molar ratio of the compound II to ethylene oxide is 10-30:1-30.

6. The method for preparing the benzimidazole-based surfactant according to claim 4, characterized in that: The preparation method of the compound II is:

7. The method for preparing the benzimidazole-based surfactant according to claim 6, characterized in that: The base is a strong inorganic base, the reaction conditions are 100-120° C. for 0.5-1 h under vacuum, and the molar ratio of the compound III to ethylene oxide is 1:10-30.

8. The method for preparing the benzimidazole-based surfactant according to claim 6, characterized in that: The preparation method of the compound III is:

9. The method for preparing the benzimidazole-based surfactant according to claim 8, characterized in that: The molar ratio of the compound IV to the compound V is 1-3:1-3, the catalyst is boric acid, and the reaction conditions are 40-80° C. for 2-8 hours.

10. Use of the benzimidazole-based surfactant according to any one of claims 1 to 3 in metal corrosion inhibition and heavy oil viscosity reduction.

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