CO2-resistant tall oil imidazoline Mannich base corrosion inhibitor, preparation method thereof and composite corrosion inhibitor

Abstract

The invention provides a CO2 tall oil-resistant imidazoline Mannich base corrosion inhibitor, a preparation method thereof and a composite corrosion inhibitor. The imidazoline Mannich base corrosion inhibitor with a hydrophilic group and a hydrophobic group is obtained by synthesizing an imidazoline ring from tall oil mixed fatty acid and organic polyamine and then condensing arone and trioxymethylene with a terminal amino group of a side chain of the imidazoline ring. According to the CO2-resistant imidazoline corrosion inhibitor, the CO2-resistant performance of the imidazoline Mannich base corrosion inhibitor in CO2 can be improved by utilizing the synergistic adsorption and isolation effects of imidazole rings with different alkyl structures and Mannich base groups in an acid medium. The imidazoline Mannich base is compounded with the surfactant O-20 and the solubilizer PEG20000, so that the corrosion inhibition performance of the corrosion inhibitor can be further improved. The product meets the environmental protection requirements of enterprises and is beneficial to industrial popularization and application.

Description

Technical field:

[0001] The invention relates to the field of corrosion protection of oil and gas field gathering and transportation pipelines, and in particular to a salt-resistant CO2 corrosion inhibitor and a preparation method and a compounding scheme thereof. Background technology:

[0002] With the rapid development of the petroleum industry, especially the widespread application of water flooding technology in oil and gas wells, the erosion of various corrosive media has led to increasingly serious corrosion problems in oil well casings, tank bottom plates, buried pipelines, and oil and gas well casings and pipelines inside oil fields. In the process of oil production, CO2 corrosion is the cause of failure of oil and gas pipelines and production equipment. Carbonic acid generated by the reaction of CO2 with water in the solution releases highly corrosive hydrogen ions during the ionization process. At the same time, due to its low price, carbon steel is widely used in the petroleum industry. However, the easy corrosion of carbon steel makes pipelines and production equipment in the process of oil and gas production face serious corrosion risks. According to a large number of previous research results, during the action of imidazoline corrosion inhibitors, it has the characteristics of oil and water dual solubility and high corrosion inhibition efficiency. Imidazoline corrosion inhibitors have attracted wide attention due to their low toxicity and excellent corrosion inhibition performance. However, as the exploitation environment of oil and gas fields becomes more harsh, the groundwater contains high chloride ion concentration and high carbon dioxide content. The imidazoline quaternary ammonium salt corrosion inhibitors widely used on the market have low corrosion inhibition rates in high-salt and CO2 corrosive media and cannot meet the requirements of enterprises in the oil industry. Due to the limitations of the molecular structure, the existing imidazoline corrosion inhibitors have low corrosion inhibition rates for Q235 carbon steel at low concentrations in salt and carbon dioxide environments, and the annual corrosion rate cannot meet the oil industry standards. Therefore, how to develop an imidazoline corrosion inhibitor that can serve in oil field gathering and transportation systems, salt and carbon dioxide environments, and has high corrosion inhibition efficiency is an urgent problem to be solved.

[0003] Technical advantages:

[0004] The invention provides a novel imidazoline corrosion inhibitor resistant to CO2 corrosive medium. By utilizing the synergistic adsorption effect, an imidazoline ring is firstly synthesized with tall oil fatty acid and organic polyamine, and then acetophenone and formaldehyde are condensed and capped with the amino group of the side chain of the imidazoline ring to obtain an imidazoline Mannich base corrosion inhibitor with excellent performance in CO2 corrosive medium, and the imidazoline Mannich base corrosion inhibitor has very strong corrosion inhibition performance under high CO2 concentration.

[0005] The synthesis process is simple, the corrosion inhibition effect is good, it is suitable for the corrosion protection of Q235 low carbon steel, and can effectively prevent the corrosion of carbon steel in a high temperature CO2 environment, with a corrosion inhibition efficiency of more than 80%. If the high temperature resistant CO2 corrosion inhibitor component is used as the main corrosion inhibitor and compounded with a synergist, the corrosion inhibition performance of the corrosion inhibitor in a high temperature environment can be further improved, and the corrosion inhibition efficiency can basically be maintained at more than 90% at 50°C. DETAILED DESCRIPTION Summary of the invention:

[0006] (1) subjecting tall oil fatty acid and organic polyamine to an amidation reaction at a temperature of 160-180° C., and then heating to 200-220° C. for a dehydration cyclization reaction to obtain an imidazoline intermediate; the molar ratio of the tall oil fatty acid to the organic polyamine is 1:1.2. The organic polyamine is diethylenetriamine or triethylenetetramine

[0007] (2) After the reaction system is cooled to room temperature, acetophenone and paraformaldehyde are added to continue the reaction to obtain a tall oil imidazoline Mannich base corrosion inhibitor. The molar ratio of the imidazoline intermediate to the acetophenone and formaldehyde is 1:1.1.

[0008] (3) It is obtained by compounding the imidazoline Mannich base corrosion inhibitor with one or more of O-20, PEG20000, and propargyl alcohol ethoxylate, which can further improve the CO2 resistance of the imidazoline corrosion inhibitor.

[0009] When compounded, the dosage of the imidazoline corrosion inhibitor is 0.004%; the dosage of the O-20 is 0.001%, the dosage of the propargyl alcohol ethoxylate is 0.001%, and the dosage of the PEG20000 is 0.001%, based on the total mass of the composite corrosion inhibitor.

[0010] The CO2 resistant corrosion inhibitor and the composite corrosion inhibitor containing the same of the present invention can be used as an oilfield corrosion inhibitor or a protective agent for metal equipment in a pickling environment. At a service temperature of 50°C, the corrosion inhibition efficiency reaches more than 92%, and has very excellent CO2 corrosion resistance. Specific implementation method:

[0012] Embodiment 1:

[0013] A CO2-resistant imidazoline Mannich base corrosion inhibitor, the preparation method of which is as follows:

[0014] (1) Tall oil fatty acid, diethylenetriamine and an appropriate amount of xylene water-carrying agent are added to a three-necked flask, and a few zeolites are added, and amidation is carried out at 170° C. for 2 hours, and then the temperature is further increased to 210° C. for dehydration and cyclization for 2 hours to obtain an imidazoline intermediate, wherein the molar ratio of tall oil fatty acid to diethylenetriamine is 1:1.2.

[0015] (2) After the reaction system is cooled to 110° C., acetophenone and trioxymethylene are added in a molar ratio of 1:1.1 of tall oil fatty acid and the reaction is continued for 3 hours to obtain a tall oil imidazoline Mannich base corrosion inhibitor.

[0016] Embodiment 2:

[0017] O-20 was added to the CO2-resistant imidazoline Mannich base corrosion inhibitor synthesized in Example 1 to prepare a composite corrosion inhibitor, wherein the mass ratio of O-20 to imidazoline Mannich base was 2:1.

[0018] Embodiment 3:

[0019] The propargyl alcohol ethoxy compound is added to the CO2-resistant imidazoline Mannich base corrosion inhibitor synthesized in Example 1 to prepare a composite corrosion inhibitor, wherein the mass ratio of the propargyl alcohol ethoxy compound to the Mannich base is 2:1.

[0020] Embodiment 4:

[0021] PEG20000 was added to the CO2-resistant imidazoline Mannich base corrosion inhibitor synthesized in Example 1 to prepare a composite corrosion inhibitor, wherein the mass ratio of PEG20000 to Mannich base was 2:1.

[0022] Embodiment 5:

[0023] O-20 and PEG20000 were added to the CO2-resistant imidazoline Mannich base corrosion inhibitor synthesized in Example 1 to prepare a composite corrosion inhibitor, wherein the mass ratio of O-20, PEG20000 and Mannich base was 1:1:3.

[0024] Embodiment 6:

[0025] O-20 and ethoxy propargyl alcohol compound were added to the CO2-resistant imidazoline Mannich base corrosion inhibitor synthesized in Example 1 to prepare a composite corrosion inhibitor, wherein the mass ratio of O-20, propargyl alcohol ethoxy compound and Mannich base was 1:1:3.

[0026] Embodiment 7:

[0027] PEG20000 and propargyl alcohol ethoxy compound were added to the CO2-resistant imidazoline Mannich base corrosion inhibitor synthesized in Example 1 to prepare a composite corrosion inhibitor, wherein the mass ratio of PEG20000, ethoxy propargyl alcohol compound and Mannich base was 1:1.

Claims

1. A CO2 resistant tall oil imidazoline Mannich base corrosion inhibitor, characterized in that: The CO2 resistant tall oil imidazoline Mannich base corrosion inhibitor has the following molecular structure:

2. A method for preparing the CO2 resistant tall oil imidazoline Mannich base corrosion inhibitor according to claim 1, characterized in that: The method comprises the following steps: S1: subjecting tall oil fatty acid to an amidation reaction with an organic polyamine at a temperature of 160-180° C., and then heating to 200-220° C. for a dehydration cyclization reaction to obtain an imidazoline intermediate; S2: After the reaction system is cooled to room temperature, acetophenone and trioxymethylene are added to continue the reaction to obtain the tall oil imidazoline Mannich base corrosion inhibitor.

3. The preparation method according to claim 2, characterized in that: The molar ratio of the tall oil fatty acid to the organic polyamine is 1:1.2; the molar ratio of the imidazoline intermediate to the aromatic ketone and the paraformaldehyde is 1:1.1:1.

1. The organic polyamine is diethylenetriamine or triethylenetetramine.

4. A composite corrosion inhibitor, characterized in that: The invention is obtained by compounding the imidazoline corrosion inhibitor with one or more of an emulsifier O-20, a solubilizer PEG20000 and an unsaturated alcohol.

5. The composite corrosion inhibitor according to claim 4, characterized in that: The unsaturated alcohol is ethoxypropynyl alcohol.

Images