Method for simulating synergistic effect of oil and gas pipeline soaking corrosion-CO2-SRB bacteria

Abstract

The invention discloses a method for simulating an oil and gas pipeline immersion corrosion-CO2-SRB bacterium synergistic effect. The technical problem that an existing experimental method for oil and gas pipeline corrosion has defects in the aspect of simulating a corrosion environment under a multi-factor synergistic effect is solved. The method comprises the following steps: collecting an oil and gas pipeline corrosion stock solution, analyzing components contained in the oil and gas pipeline corrosion stock solution, combining oil and gas pipeline operation process parameters including pressure, temperature, materials and the like borne during operation, formulating matched experimental research parameters, building a static corrosion experimental device according to requirements of laboratory research parameters, carrying out a static corrosion experiment on a target material, and after the experiment, carrying out static corrosion analysis on the target material. And taking out the test material, pickling, weighing, calculating the corrosion rate, analyzing the corrosion morphology and the corrosion product, and researching the corrosion law and mechanism. According to the method, the corrosion behavior of the pipeline material in the specific environment is known, targeted protection measures can be formulated, the service life of the pipeline is prolonged, and safety accidents and environmental damage caused by corrosion are reduced.

Description

Technical Field

[0001] The invention relates to the technical field of oil and gas pipeline corrosion protection, and in particular to a method for simulating the synergistic effect of oil and gas pipeline immersion corrosion-CO2-SRB bacteria. Background Art

[0002] In oil and gas pipeline systems, corrosion is a serious problem that can lead to pipeline failure and leakage, which in turn damages the environment and may even cause safety accidents. Factors such as water content, carbon dioxide and sulfate-reducing bacteria (SRB) corrosion are the main causes of pitting and perforation in gathering and transportation pipelines. Most current research focuses on the material corrosion failure mechanism under a single influencing factor. However, actual pipeline corrosion is often a complex process caused by the combined action of multiple factors.

[0003] Existing experimental methods and devices for oil and gas pipeline corrosion have shortcomings, especially in simulating the corrosion environment under the synergistic effect of multiple factors. Traditional experimental methods often only consider a single corrosion factor, such as CO2 corrosion or SRB corrosion alone, without combining multiple corrosion factors for simulation. Such experimental methods cannot accurately reflect the actual situation of pipeline corrosion, nor can they provide reliable data support for the formulation of effective corrosion protection measures.

[0004] To address this issue, there is an urgent need for a corrosion test method that can simulate the corrosion of oil and gas pipelines under the synergistic effect of multiple factors, so as to more accurately evaluate the corrosion resistance of pipeline materials and provide an effective basis for pipeline corrosion protection and material selection. Summary of the invention

[0005] The purpose of the present invention is to provide a method for simulating the immersion corrosion of oil and gas pipelines-CO2-SRB bacteria synergy, so as to solve the technical problem that the existing experimental methods for oil and gas pipeline corrosion are insufficient in simulating the corrosion environment under the synergistic effect of multiple factors.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] The present invention provides a method for simulating the synergistic effect of oil and gas pipeline immersion corrosion-CO2-SRB bacteria, comprising the following steps:

[0008] Step 1: Collect the corrosive media in the oil and gas pipeline under on-site working conditions and analyze their components;

[0009] Step 2: Collecting on-site operating parameters and historical operating parameters of oil and gas pipelines;

[0010] Step 3: Formulate a static corrosion test plan based on the analysis of the components of the corrosive media in the oil and gas pipeline and its operating parameters under the on-site working conditions;

[0011] Step 4: Build a static corrosion test device;

[0012] Step 5: Conduct a static corrosion test on the target material using a static corrosion test device;

[0013] Step 6: After several days of testing using a static corrosion test device, the sample is taken out, pickled, weighed, and then the corrosion rate is calculated;

[0014] Step 7, analyzing the microscopic corrosion morphology of the sample and the corrosion products derived from the corrosion, including corrosion product analysis, macroscopic corrosion morphology analysis and microscopic corrosion morphology analysis;

[0015] Step 8: Summarize the results of corrosion rate, corrosion morphology and corrosion product analysis, and analyze the corrosion law and mechanism of the target pipeline material under the synergistic action of immersion corrosion-CO2-SRB bacteria.

[0016] Furthermore, in step 1, the component analysis includes:

[0017] Corrosive medium composition analysis: Determination of the composition of the corrosive medium under on-site working conditions, including ion composition and CO2 content;

[0018] Microbial analysis: Based on the presence of microorganisms in the corrosive medium under on-site working conditions, bacterial liquid sampling and analysis are carried out, and the types and contents of microorganisms are detected through microbial 16s rDNA testing and microbial culture methods.

[0019] Furthermore, in step 2, the operating parameters include pipeline material, corrosive medium temperature and operating pressure in the pipeline.

[0020] Furthermore, in step 4, the static corrosion experimental device includes a temperature control unit, a gas control unit, and a sample loading and fixing unit; the temperature control unit is achieved by winding a heating belt on the experimental container, cooperating with a temperature sensor and an adjustment module to achieve temperature control, thereby obtaining different test medium temperatures; the gas control unit utilizes a gas cylinder, in conjunction with the inlet and outlet holes on the lid of the experimental container, to introduce different proportions of gas into the test medium to achieve experimental conditions with different CO2 contents; the sample loading and fixing unit includes an experimental container and a sample clamp, and the sample is fixed to the bottom edge of the experimental container. Through this device, static corrosion experiments under different temperatures and different gas composition combinations can be achieved.

[0021] Furthermore, the step 5 specifically includes the following steps:

[0022] Step 51, experimental solution preparation: prepare a simulated solution according to the analysis of the components of the corrosive medium in the pipeline under the on-site working conditions;

[0023] Step 52, setting experimental parameters: setting different experimental pressures, CO2 contents, SRB reducing bacteria contents and multi-factor combination experimental conditions to study the synergistic effect of different influencing factors; determining the experimental parameters of the control group according to the on-site produced fluid and operating conditions, including temperature, pressure, CO2 content, SRB bacteria content, etc., and then comparing the control group experiment, using a single variable method, respectively changing the temperature, pressure, CO2 content, SRB bacteria content and other parameters to carry out multi-factor combination experiments, and finally comparing and analyzing the experimental results under different experimental conditions to summarize the experimental rules;

[0024] Step 53, sample specifications: There are two specifications, one is a 60mm×20mm×3mm corrosion weight loss sample, 3 samples per group; the other is a 20mm×20mm×3mm detection and analysis sample, 2 samples per group.

[0025] Further, in step 6, the specific process of calculating the corrosion rate is: after the experiment, take out the corrosion sample, pickle it with pickling solution, rinse it with alcohol, blow it dry with cold air, weigh it and record it, and calculate the corrosion rate based on the weight after pickling. The calculation formula is as follows:

[0026]

[0027] Where: R——corrosion rate, mm / a;

[0028] M——mass of sample before the experiment, g;

[0029] M1——mass of sample after the test, g;

[0030] S——total area of ​​the sample, cm 2 ;

[0031] T——experimental time, h;

[0032] D——density of the material, kg / m 3 .

[0033] Furthermore, in step 7, the corrosion product analysis is to detect the corrosion product composition and elements through the scanning electron microscope energy spectrum analyzer or sampling of the corrosion product XRD detection; the macro corrosion morphology analysis is to scan and detect the surface defects of the sample, and further carry out non-destructive testing; the micro corrosion morphology analysis uses a scanning electron microscope to perform microscopic analysis of its metallographic structure, obtain the second phase precipitation and organizational morphology in the metallographic structure, and use an energy spectrometer to perform elemental qualitative determination and analysis on its surface composition and attachments.

[0034] Furthermore, the corrosion product analysis uses a scanning electron microscope energy spectrum analyzer to perform chemical composition analysis, including analysis of C, Si, Mn, S, P, Cr, Ni, Mo, Nb and Ti elements.

[0035] Based on the above technical solution, the embodiments of the present invention can at least produce the following technical effects:

[0036] The present invention provides a method for simulating the immersion corrosion-CO2-SRB bacterial synergy of oil and gas pipelines. The corrosive medium in the oil and gas pipeline under the field working condition is collected and its components are analyzed in detail. In combination with the operating parameters and historical operating parameters of the oil and gas pipeline under the field working condition, including operating pressure, temperature, flow rate, material, etc., the experimental research parameters are established, covering aspects such as the preparation of simulated solution, SRB bacterial culture, gas composition ratio and temperature control. According to the experimental parameter requirements, a static corrosion experimental device is established, and a static corrosion experiment is carried out on the target material. After the experiment is completed, the test material is extracted to calculate the corrosion rate, and the corrosion morphology, derived corrosion products, etc. are analyzed in detail using electron scanning microscopy technology and phase analysis technology (such as SEM, XRD, etc.). Through this series of steps, it is intended to deeply study the corrosion law and mechanism of the target pipeline material under the immersion corrosion-CO2-SRB bacterial synergy, which can provide an effective basis for corrosion protection and material selection of oil and gas pipelines. Understanding the corrosion behavior of pipeline materials under specific environments is helpful to formulate targeted protection measures, extend the service life of pipelines, and reduce safety accidents and environmental damage caused by corrosion. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0038] Figure 1 is a flow chart of an embodiment of the present invention;

[0039] Figure 2 It is a structural schematic diagram of the static corrosion experimental device of the present invention;

[0040] Figure 3 is a graph of the corrosion rate of an embodiment of the present invention under different CO2 partial pressures;

[0041] Figure 4 This is a macroscopic morphology diagram of an embodiment of the present invention under different CO2 partial pressures;

[0042] Figure 5 is a microscopic corrosion morphology diagram of an embodiment of the present invention under saturated CO2 partial pressure;

[0043] Figure 6This is a microscopic corrosion morphology diagram of an embodiment of the present invention under a CO2 partial pressure of 0.02Mpa;

[0044] Figure 7 This is a microscopic corrosion morphology diagram of an embodiment of the present invention under a CO2 partial pressure of 0.04Mpa;

[0045] Figure 8 This is a microscopic corrosion morphology diagram of an embodiment of the present invention under a CO2 partial pressure of 0.06Mpa;

[0046] Fig. 9 It is a microscopic corrosion morphology diagram of an embodiment of the present invention under a CO2 partial pressure of 0.1 MPa. DETAILED DESCRIPTION

[0047] The technical solutions in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in this field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0048] The embodiment of the present invention discloses a static corrosion test method for simulating oil and gas pipeline immersion corrosion-CO2-SRB bacteria synergy, such as Figure 1 As shown, the corrosion law and mechanism of the target pipeline material under the synergistic action of immersion corrosion-CO2-SRB bacteria are studied. By collecting the corrosive media in the oil and gas pipeline under field conditions and analyzing their components, combining the operating parameters of the oil and gas pipeline under field conditions and historical operating parameters, formulating experimental research parameters, building a static corrosion experimental device, and conducting static corrosion experiments on target materials, the corrosion law and mechanism of the target pipeline material under the synergistic action of immersion corrosion-CO2-SRB bacteria are studied, all of which provide an effective basis for on-site corrosion protection and material selection. Specifically, the following steps are included:

[0049] Step 1: Collect the corrosive media in the oil and gas pipeline under on-site working conditions and analyze their components;

[0050] Collecting corrosive media in oil and gas pipelines and analyzing their composition include:

[0051] Corrosive medium composition analysis: Determination of the composition content of the corrosive medium under on-site working conditions, including ion composition determination (anion type and content and cation type and content), CO2 content, etc.;

[0052] Microbial analysis: Based on the possible presence of microbial corrosion media under on-site working conditions, bacterial liquid sampling and analysis are carried out, and the types and contents of microorganisms are detected through microbial 16s rDNA testing and microbial culture methods.

[0053] Step 2: Collect the on-site operating parameters and historical operating parameters of the oil and gas pipeline; the operating parameters include: pipeline material, corrosive medium temperature, operating pressure in the pipeline, etc.

[0054] Step 3: Develop a static corrosion test plan based on the analysis of the corrosive medium composition and operating parameters in the oil and gas pipeline under on-site conditions.

[0055] Step 4: Build a static corrosion test device, such as Figure 2 As shown in the figure, the static corrosion test device mainly includes four parts: temperature control unit, gas control unit, and sample loading and fixing unit. Specifically, the temperature control unit is to achieve temperature control by winding a heating belt on the experimental container, cooperating with a temperature sensor and an adjustment module, so as to obtain different test medium temperatures. The gas control unit uses a gas cylinder and cooperates with the inlet and outlet holes on the lid of the experimental container to pass different proportions of gas into the test medium to achieve experimental conditions with different CO2 contents. The sample loading and fixing unit includes an experimental container and a sample fixture to fix the sample on the bottom edge of the container. This device can realize static corrosion experiments under different temperatures and different gas composition combinations.

[0056] Step 5: Conduct a static corrosion test on the target material using a static corrosion test device;

[0057] According to the on-site working conditions of the oil and gas pipeline, the corrosive media in the pipeline, the on-site working conditions of the oil and gas pipeline and the historical operating parameters, the static corrosion test conditions are formulated to carry out the static corrosion test of the target material. Including:

[0058] Preparation of experimental solution: Prepare the simulated solution based on the analysis of the components of the corrosive medium in the pipeline under on-site working conditions.

[0059] Experimental parameter setting: set different experimental pressures, CO2 contents, SRB reducing bacteria contents and other combined experimental conditions to study the synergistic effect of different influencing factors; specifically, determine the experimental parameters of the control group according to the on-site produced fluid and operating conditions, including temperature, pressure, CO2 content, SRB bacteria content, etc., and then compare the control group experiment. Use the single variable method to change the temperature, pressure, CO2 content, SRB bacteria content and other parameters to carry out multi-factor combination experiments. Finally, compare and analyze the experimental results under different experimental conditions to summarize the experimental rules.

[0060] Sample specifications: There are two specifications, one is a 60mm×20mm×3mm corrosion weight loss sample, 3 samples per group; the other is a 20mm×20mm×3mm detection and analysis sample, 2 samples per group. The specific sample size can be determined according to specific experimental requirements.

[0061] Step 6. After the experiment, take out the corrosion sample, pickle it with pickling solution, rinse it with alcohol, blow it dry with cold air, weigh it and record it. The corrosion rate is calculated based on the weight after pickling. The calculation formula is as follows:

[0062]

[0063] Where: R——corrosion rate, mm / a;

[0064] M——mass of sample before the experiment, g;

[0065] M1——mass of sample after the test, g;

[0066] S——total area of ​​the sample, cm 2 ;

[0067] T——experimental time, h;

[0068] D——density of the material, kg / m 3 .

[0069] Step 7: Analyze the microscopic corrosion morphology and corrosion products derived from corrosion by combining scanning electron microscopy technology and phase analysis technology (SEM, XRD, etc.); specifically including:

[0070] Corrosion product analysis: The corrosion product composition and elements are tested by scanning electron microscope energy spectrum analyzer or sampling corrosion product XRD test;

[0071] Macro-corrosion morphology analysis: Scan and detect surface defects of the sample, and further carry out non-destructive testing.

[0072] Microscopic corrosion morphology analysis: Scanning electron microscope was used to conduct microscopic analysis of the metallographic structure to obtain the second phase precipitation and organizational morphology in the metallographic structure, and energy spectrometer was used to conduct elemental qualitative determination and analysis of the surface composition and attachments.

[0073] The chemical composition of the target pipeline material samples was analyzed using a scanning electron microscope energy spectrum analyzer, including analysis of C, Si, Mn, S, P, Cr, Ni, Mo, Nb and Ti elements.

[0074] Step 8: Summarize the results of corrosion rate, corrosion morphology and corrosion product analysis, and analyze the corrosion law and mechanism of the target pipeline material under the synergistic action of immersion corrosion-CO2-SRB bacteria.

[0075] In this implementation case, the corrosive medium in the oil and gas pipeline under field conditions was measured. The Cl concentration in the corrosive medium was 7240-21900 mg / L, belonging to the CaCl2 type, with a pH value of 6-8.5. The ion content of the produced water is shown in Table 1 below, and the SRB bacteria content is as high as 700,000 / ml.

[0076] Table 1 Ion content of produced water

[0077]

[0078] In this implementation case, static corrosion test parameters were formulated based on the analysis of the components of the corrosive medium in the oil and gas pipeline under field conditions, mainly to study the corrosion laws and mechanisms at different CO2 partial pressures under certain temperatures and conditions containing SRB bacteria. The experimental parameters are shown in Table 2 below:

[0079] Table 2 Experimental parameters

[0080] Serial number Temperature, °C <![CDATA[Partial pressure of CO2, MPa]]> Time, day SRB bacteria 1 40 saturation 12 Contains bacteria, Xinsheng 5ml 2 40 0.02 12 Contains bacteria, Xinsheng 5ml 3 40 0.04 12 Contains bacteria, Xinsheng 5ml 4 40 0.06 12 Contains bacteria, Xinsheng 5ml 5 40 0.1 12 Contains bacteria, Xinsheng 5ml

[0081] In this implementation case, after the experiment, the solution characteristics were observed, the SRB bacterial content was determined, and the analysis and test results are shown in Table 3. Under the five CO2 partial pressure conditions, the solution had an odor after the experiment, among which the saturated partial pressure had a weak odor, the solution was light yellow, and there was a small amount of red precipitate, the 0.02MPa, 0.04MPa, and 0.06MPa partial pressures had a slight rotten egg smell, the solution was transparent, and there was a small amount of black precipitate, and the 0.1MPa partial pressure had a slight rotten egg smell, the solution was translucent and black, and there was a small amount of black precipitate. A large number of SRB bacteria existed under all partial pressure conditions. The results showed that hydrogen sulfide was produced in the solution due to the activity of SRB bacteria during the experiment.

[0082] Table 3 Experimental phenomena

[0083] Partial Pressure odor Solution precipitation SRB content, pieces / ml saturation Weak smell Light yellow red <![CDATA[9.5×10 3 ]]> 0.02 Slight rotten egg smell transparent black <![CDATA[>10 5 ]]> 0.04 Slight rotten egg smell transparent black <![CDATA[>10 5 ]]> 0.06 Slight rotten egg smell transparent black <![CDATA[>10 5 ]]> 0.1 Slight rotten egg smell Translucent black black <![CDATA[>10 5 ]]>

[0084] In this embodiment, after the experiment, the sample was taken out from the solution, and was weighed after acid washing. The corrosion rate was calculated by weight loss method. The results are as follows: Figure 3 As shown in the figure, under static conditions, the corrosion rate is the highest at 0.1MPa-CO2 partial pressure. Under saturated CO2 partial pressure, 0.04MPa-CO2 partial pressure, and 0.06MPa-CO2 partial pressure, the corrosion rates are close. Under 0.02MPa-CO2 partial pressure, the corrosion rate is lower. Figure 4 As shown in Figure 2, the microscopic corrosion morphology is as follows: Figure 5-Figure 9 As shown. Figure 4It can be seen that under static conditions, there is a large amount of rust on the surface of the saturated CO2 partial pressure sample, and the metal matrix is ​​largely covered, with only a small amount of metal matrix visible. Under 0.02MPa-CO2 partial pressure, 0.04MPa-CO2 partial pressure, 0.06MPa-CO2 partial pressure, and 0.1MPa-CO2 partial pressure conditions, there is more floating rust on the surface of the sample, and it is relatively loose, with slightly less rust than under saturated partial pressure conditions. Figure 5 It can be seen that under static conditions, the surface of the saturated CO2 partial pressure sample is covered with a large number of clustered corrosion products, and the film layer is loose. Figure 6 It can be seen that the sample under static conditions with a partial pressure of 0.02 MPa-CO2 has a smooth and dense biofilm (S1.35%), and other locations are loose FeCO3 particles, with large villi or spherical clusters with extracellular polysaccharide fibers in some places. Figure 7 It can be seen that the morphology of the sample with a CO2 partial pressure of 0.04MPa under static conditions is similar to that of the sample with a CO2 partial pressure of 0.02MPa. Figure 8 It can be seen that under static conditions, the 0.06MPa-CO2 partial pressure sample has a biofilm (S0.63%), and other locations have alternating flake and cluster corrosion products, and no FeCO3 particles are seen. Fig. 9 It can be seen that under static conditions, there is a biofilm (S6.9%) on the surface of the sample with a partial pressure of 0.1MPa-CO2, and flaky corrosion products in other locations, with local cracks, indicating that the corrosion products are thick and cracked due to internal stress, and no FeCO3 particles are found. The main elements on the surface of the sample measured by EDS are C, O, Fe, and a small amount of S.

[0085] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements fall within the scope of the present invention to be protected. The scope of the present invention to be protected is defined by the attached claims and their equivalents.

Claims

1. A method for simulating the synergistic effect of oil and gas pipeline immersion corrosion-CO2-SRB bacteria, characterized in that: The following steps are involved: Step 1: Collect the corrosive media in the oil and gas pipeline under on-site working conditions and analyze their components; Step 2: Collecting on-site operating parameters and historical operating parameters of oil and gas pipelines; Step 3: Formulate a static corrosion test plan based on the analysis of the components of the corrosive media in the oil and gas pipeline and its operating parameters under the on-site working conditions; Step 4: Build a static corrosion test device; Step 5: Conduct a static corrosion test on the target material using a static corrosion test device; Step 6: After several days of testing using a static corrosion test device, the sample is taken out, pickled, weighed, and then the corrosion rate is calculated; Step 7, analyzing the microscopic corrosion morphology of the sample and the corrosion products derived from the corrosion, including corrosion product analysis, macroscopic corrosion morphology analysis and microscopic corrosion morphology analysis; Step 8: Summarize the results of corrosion rate, corrosion morphology and corrosion product analysis, and analyze the corrosion law and mechanism of the target pipeline material under the synergistic action of immersion corrosion-CO2-SRB bacteria.

2. The method for simulating oil and gas pipeline immersion corrosion-CO2-SRB bacteria synergy according to claim 1, characterized in that: In step 1, the component analysis includes: Corrosive medium composition analysis: Determination of the composition of the corrosive medium under on-site working conditions, including ion composition and CO2 content; Microbial analysis: Based on the presence of microbial corrosion media under on-site working conditions, bacterial liquid sampling and analysis are carried out, and the types and contents of microorganisms are detected through microbial 16s rDNA testing and microbial culture methods.

3. The method for simulating oil and gas pipeline immersion corrosion-CO2-SRB bacteria synergy according to claim 1, characterized in that: In step 2, the operating parameters include pipeline material, corrosive medium temperature and operating pressure in the pipeline.

4. The method for simulating oil and gas pipeline immersion corrosion-CO2-SRB bacteria synergy according to claim 1, characterized in that: In step 4, the static corrosion experiment device includes a temperature control unit, a gas control unit, and a sample loading and fixing unit; the temperature control unit realizes temperature control by winding a heating belt on the experimental container, cooperating with a temperature sensor and an adjustment module, so as to obtain different test medium temperatures; the gas control unit utilizes a gas cylinder, cooperates with the inlet and outlet holes on the lid of the experimental container, and introduces different proportions of gas into the test medium to achieve experimental conditions with different CO2 contents; the sample loading and fixing unit includes an experimental container and a sample clamp, and fixes the sample on the bottom edge of the experimental container. Through this device, static corrosion experiments under different temperatures and different gas composition combinations can be realized.

5. The method for simulating oil and gas pipeline immersion corrosion-CO2-SRB bacteria synergy according to claim 1, characterized in that: The step 5 specifically comprises the following steps: Step 51, experimental solution preparation: prepare a simulated solution according to the analysis of the components of the corrosive medium in the pipeline under the on-site working conditions; Step 52, setting experimental parameters: setting experimental conditions of multiple influencing factors such as different experimental pressures, CO2 contents, and SRB-reducing bacteria contents to study the synergistic effects of different influencing factors; Step 53, sample specifications: There are two specifications, one is a 60mm×20mm×3mm corrosion weight loss sample, 3 samples per group; the other is a 20mm×20mm×3mm detection and analysis sample, 2 samples per group.

6. The method for simulating oil and gas pipeline immersion corrosion-CO2-SRB bacteria synergy according to claim 1, characterized in that: In step 6, the specific process of calculating the corrosion rate is as follows: after the experiment, the corrosion sample is taken out, pickled with pickling solution, rinsed with alcohol, dried with cold air, weighed and recorded, and the corrosion rate is calculated based on the weight after pickling. The calculation formula is as follows: Where: R——corrosion rate, mm / a; M——mass of sample before the experiment, g; M1——mass of sample after the test, g; S——total area of ​​the sample, cm 2 ; T——experimental time, h; D——density of the material, kg / m 3 .

7. The method for simulating oil and gas pipeline immersion corrosion-CO2-SRB bacteria synergy according to claim 1, characterized in that: In step 7, the corrosion product analysis is to detect the corrosion product composition and elements through scanning electron microscope energy spectrum analyzer detection or sampling of corrosion product XRD detection; the macro corrosion morphology analysis is to scan and detect the surface defects of the sample, and further carry out non-destructive testing; the micro corrosion morphology analysis uses a scanning electron microscope to perform microscopic analysis of its metallographic structure, obtain the second phase precipitation and organizational morphology in the metallographic structure, and use an energy spectrometer to perform elemental qualitative determination and analysis on its surface composition and attachments.

8. The method for simulating oil and gas pipeline immersion corrosion-CO2-SRB bacteria synergy according to claim 7, characterized in that: The corrosion product analysis uses a scanning electron microscope energy spectrum analyzer to perform chemical composition analysis, including analysis of C, Si, Mn, S, P, Cr, Ni, Mo, Nb and Ti elements.

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