Method for simulating hydrogen permeation value of defective pipeline influenced by corrosion of sulfate reducing bacteria

Abstract

The invention provides a numerical simulation method for hydrogen permeation of a defective pipeline influenced by corrosion of sulfate reducing bacteria. Comprising the following steps: (1) determining hydrogen permeation key parameters of a pipeline in a sulfate reducing bacteria corrosion environment through a sulfate reducing bacteria corrosion simulation experiment; and (2) constructing a multi-physics field coupling model by utilizing a finite element method, and realizing the numerical simulation of the hydrogen concentration distribution of the defective pipeline under the corrosion influence of the sulfate reducing bacteria through coupling of an electrochemical physics field and a substance transfer physics field. And (3) outputting a hydrogen concentration distribution result of the defect-containing pipeline, and revealing an influence rule of corrosion of the sulfate reducing bacteria on the hydrogen concentration distribution. According to the method, the technical blank of hydrogen permeation numerical simulation of the defect-containing pipeline in a sulfate reducing bacteria corrosion scene is filled, and theoretical support is provided for hydrogen damage evaluation, safety design and protection of the defect-containing pipeline.

Description

Technical Field

[0001] This invention relates to the field of corrosion protection and integrity management of oil and gas pipelines, specifically to a numerical simulation method for hydrogen permeation behavior in defective pipelines under the influence of sulfate-reducing bacteria corrosion. Background Technology

[0002] During oil and gas transportation, the inner walls of pipelines often develop anaerobic environments due to factors such as water accumulation and sediment deposits, becoming breeding grounds for sulfate-reducing bacteria (SRB). SRB metabolism reduces sulfates to sulfides, leading not only to severe pitting and under-deposit corrosion, creating defects, but also significantly promoting hydrogen atom penetration into the steel through its H2S metabolites and the resulting environment. Hydrogen atoms that have entered the steel accumulate at defects or stress concentration points, easily inducing hydrogen-induced cracking or sulfide stress corrosion cracking, seriously threatening the safe operation of the pipeline.

[0003] Currently, assessments of pipeline hydrogen damage risk are primarily based on standard dual-electrolysis cell hydrogen permeation experiments and stress-coupled hydrogen diffusion models. However, these methods do not adequately consider the complex effects of microbial corrosion, particularly SRB corrosion. The impact of SRB is dynamic and involves multiple coupled factors: on the one hand, the SRB corrosion process itself is a continuous source of hydrogen atoms; on the other hand, SRB biofilms and their corrosion products may act as diffusion barriers, affecting hydrogen ingress. Existing technologies lack numerical models capable of describing the coupling effect between SRB corrosion reactions and the hydrogen permeation process, making it difficult to accurately predict the internal hydrogen concentration field of defective pipelines under SRB conditions, thus limiting the effective assessment of pipeline hydrogen damage risk under such special corrosive environments. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a numerical simulation method for hydrogen permeation in defective pipelines affected by sulfate-reducing bacteria corrosion. This method utilizes the finite element method to reveal the coupled influence between the degree of sulfate-reducing bacteria corrosion and the hydrogen permeation behavior of the pipeline, providing a theoretical basis for corrosion protection and safety assessment of defective pipelines.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A numerical simulation method for hydrogen permeation in defective pipelines affected by sulfate-reducing bacteria corrosion includes the following steps:

[0007] Step S1: Obtain the initial simulation parameters through corrosion experiments;

[0008] Step S2: Construct the physical field coupling of current distribution and mass transfer using finite element software;

[0009] Step S3: Analyze the impact of sulfate-reducing bacteria corrosion on the hydrogen concentration distribution in defective pipelines.

[0010] Step S1, obtaining the initial simulation parameters, specifically includes the following steps;

[0011] Furthermore, the method for obtaining the initial simulation parameters in step S1 is as follows:

[0012] Step S11: Select a pipeline steel sample with the same material as the actual pipeline, and process the sample size to meet the requirements of hydrogen permeation and dynamic polarization tests;

[0013] Step S12: Pre-treat the sample by grinding, cleaning, dehydration and drying in sequence to remove oxide scale, oil and impurities from the sample surface and ensure that the sample surface is uniform.

[0014] Step S13: Construct a sulfate-reducing bacteria corrosion system, prepare a simulation solution to simulate the actual service environment, inoculate the target sulfate-reducing bacteria, and control the corrosion environment parameters;

[0015] Step S14: Place the pretreated sample in a sulfate-reducing bacteria corrosion system and conduct a corrosion experiment. The corrosion time is determined based on the actual service life of the pipeline.

[0016] Step S15: After the corrosion experiment, the hydrogen permeation current density-time curve and polarization curve were measured using the electrochemical hydrogen charging test method and the dynamic polarization test method.

[0017] Step S16: Obtain the cathodic and anodic Tafel slopes (b) of the corrosion experiment by fitting polarization curves. a b c ), and the exchange current density of the cathode and anode (I 0a I 0c ), corrosion current density (I) corr );

[0018] Step S17: Process the hydrogen permeation current density time-time curve using a constant concentration model to obtain the surface hydrogen concentration (C0) and hydrogen diffusion coefficient (D). eff ), hydrogen permeation flux (J).

[0019] Furthermore, the method for constructing the multiphysics coupling model in step S2 is as follows:

[0020] Step S21: Establish a physical model: Based on the actual pipe size parameters, establish a suitable pipe model with defects and define it as the metal domain. Construct a sulfate-reducing bacteria corrosion environment to simulate the service of the pipe and define it as the electrolyte domain. The contact surface between the electrolyte domain and the metal domain is the electrode surface.

[0021] Step S22: Configure the physical field: Add an electrochemical physical field to the metal domain to simulate the anodic dissolution reaction and cathodic reduction reaction in the corrosion process. Add a mass transfer physical field to the entire physical model to describe the diffusion, convection and migration processes of substances such as hydrogen ions and sulfate ions in the electrolyte domain and the diffusion of hydrogen atoms in the metal domain.

[0022] Step S23: Set up multi-physics coupling relationship: The substances consumed or generated by the electrochemical reaction are replenished or diffused through the mass transfer process, affecting the corrosion reaction; at the same time, the change in the concentration of substances during the mass transfer process will change the rate and distribution of the electrochemical reaction, thereby affecting the generation and penetration of hydrogen.

[0023] The coupling relationship is specifically constructed using the following formula:

[0024] The core formula for the electrochemical physical field was determined through corrosion reaction kinetics: the Butler-Volmer equation was used to describe the electrode reaction rate. This equation is the core equation characterizing the relationship between electrochemical reaction current density and overpotential, and its specific form is as follows:

[0025]

[0026] In the formula, I is the corrosion current density (A / m). 2 I0 is the exchange current density (A / m). 2 (from the experimental determination in step S15). , These are the cathode and anode transfer coefficients, respectively (which can be obtained using empirical values ​​or experimental fitting, and are usually taken as 0.5), and F is the Faraday constant (a fixed value of 96485 C / mol). R is the overpotential (V), R is the gas constant (fixed value 8.314 J / (mol·K)), and T is the absolute temperature (K, which is the control temperature of the sulfate-reducing bacteria corrosion simulation experiment in step S14).

[0027] The core formula of the physical field for mass transfer is determined by "concentration diffusion + migration": The Nernst-Planck equation is used to describe the transfer process of key substances (such as H⁺, SO₄²⁻, etc.) in corrosive liquids, covering three transfer forms: diffusion, migration and convection, as follows.

[0028]

[0029] In the formula: C i Let D be the concentration of substance i (mol / m³), t be time (s), and D be the concentration of substance i (mol / m³). i Z represents the diffusion coefficient of substance i (m² / s, which can be determined experimentally or obtained by consulting relevant literature). i Let be the charge number of substance i. R is the electrode potential (V, obtained from the electrochemical physical field), v is the solution flow rate (m / s, taken as 0 in static corrosion experiments), and R is the electrode potential (V, obtained from the electrochemical physical field). i The generation / consumption rate of substance i (mol / (m³·s)) is a key parameter for realizing the coupling of electrochemistry and mass transfer, and is derived from the electrochemical reaction rate.

[0030] Electrochemical-mass transport coupling correlation, the specific correlation is as follows:

[0031]

[0032] In the formula: n is the number of electrons transferred in the electrochemical reaction, and different electrode reactions correspond to different n values;

[0033] The specific relationship between the reaction transported by the reactants and the electrochemical kinetic parameters is as follows:

[0034]

[0035] In the formula, C i , The concentration of substance i at the solution and at the electrode surface (mol / m³, determined by the mass transfer process in the solution).

[0036] Coupling formula for hydrogen atoms penetrating into metals:

[0037]

[0038] In the formula, k1 is the ratio of hydrogen atoms penetrating into the metal to the total hydrogen atoms produced by the cathode reaction (calculated from the corrosion current density and surface hydrogen atom concentration obtained in step S1), I c Cathode current density (A / m) 2 ).

[0039] Step S24: Input the key hydrogen permeation parameters and corrosion-related parameters obtained in step S1 into the model as the initial parameters and material properties of the coupled model.

[0040] Furthermore, the method for analyzing the hydrogen concentration distribution in the pipeline in step S3 is as follows:

[0041] Step S31: Solve the multiphysics coupling model, run the solution module of the finite element software, solve the coupling equation, and obtain numerical simulation results such as hydrogen concentration distribution cloud map, hydrogen concentration gradient distribution and hydrogen permeation flux distribution of defective pipelines under different corrosion times and different sulfate-reducing bacteria corrosion degrees.

[0042] Step S32: Verify the accuracy of the simulation results. Conduct sulfate-reducing bacteria corrosion and hydrogen permeation experiments on defective pipelines to measure the actual corrosion current density and hydrogen permeation flux. Compare the results with the numerical simulation results and correct the model parameters (such as hydrogen diffusion coefficient, boundary conditions, etc.) to ensure the reliability of the simulation results.

[0043] Step S33: Analyze the influence of sulfate-reducing bacteria corrosion degree on hydrogen concentration distribution. Keeping other parameters constant, change parameters such as sulfate-reducing bacteria concentration and corrosion time to simulate different corrosion degrees. Compare the hydrogen concentration distribution characteristics of the defect area and surrounding area under different corrosion degrees to reveal the intrinsic relationship between sulfate-reducing bacteria corrosion degree and hydrogen concentration peak and hydrogen concentration gradient. Analyze the coupling effect of defect parameters such as defect size, depth, and shape with sulfate-reducing bacteria corrosion degree on hydrogen permeation behavior, providing a theoretical basis for corrosion protection and safety assessment of defective pipelines.

[0044] The beneficial effects of this invention are as follows: Initial simulation parameters are obtained through corrosion experiments; then, finite element method software is used to construct the physical field coupling of current distribution and mass transfer; finally, the influence of sulfate-reducing bacteria corrosion on the hydrogen concentration distribution of defective pipelines is analyzed. This invention fills the technical gap in numerical simulation of hydrogen permeation in defective pipelines under sulfate-reducing bacteria corrosion scenarios, providing theoretical support for hydrogen damage assessment, safety design, and protection of defective pipelines. Attached Figure Description

[0045] Figure 1 This is a technical roadmap for the present invention;

[0046] Figure 2 This is a diagram illustrating the modeling mechanism of defective pipelines in this invention. Detailed Implementation

[0047] The specific embodiments of the present invention will be further described below.

[0048] This invention provides a numerical simulation method for hydrogen permeation in defective pipelines affected by sulfate-reducing bacteria corrosion, such as... Figure 1 As shown, it includes:

[0049] Electrochemical experiments were conducted on pipeline steel samples. Before the electrochemical experiments, the pipeline steel samples were ground, cleaned, dehydrated, and dried. Polarization curves and hydrogen permeation current density-time curves of the pipeline steel under different SRB corrosion environments were measured using dynamic polarization and electrochemical hydrogen charging methods. The anode-cathode exchange current density (Ia) was obtained by fitting the polarization curves. 0a I 0c Electrochemical reaction kinetic parameters were used, and a constant concentration model was employed to process the hydrogen permeation current density-time curve, calculating the effective hydrogen diffusion coefficient D. eff Hydrogen permeation parameters.

[0050] Establish a suitable pipeline model with defects, such as Figure 2 As shown. An electrochemical physical field is added to the metallic domain, and a mass transfer physical field is added to the entire physical model. The substances consumed or generated by the electrochemical reaction are replenished or diffused through the mass transfer process, affecting the corrosion reaction. At the same time, changes in the concentration of substances during mass transfer will change the rate and distribution of the electrochemical reaction, thus affecting hydrogen production and permeation. Specifically, the core formula of sub-step S23 in the above technical solution is used to construct the coupling relationship, including the Butler-Volmer equation, the Nernst-Planck equation, and the electrochemical-mass transfer coupling correlation. The hydrogen diffusion coefficient, exchange current density, and other parameters obtained by fitting the hydrogen permeation current density-time curve and polarization curve in step S1 are input into the model, and corrosion environment parameters such as pH value and temperature, as well as material properties such as the conductivity and elastic modulus of the pipeline are set.

[0051] To verify the accuracy of the simulation results, sulfate-reducing bacteria corrosion and hydrogen permeation experiments were conducted on defective pipelines. The actual corrosion current density and hydrogen permeation flux were measured and compared with the numerical simulation results to correct model parameters such as hydrogen diffusion coefficient and boundary conditions.

[0052] By comparing the hydrogen concentration distribution characteristics of the defect area and surrounding area under different SRB corrosion degrees, the intrinsic relationship between SRB corrosion degree and hydrogen concentration distribution is revealed, and the influence of the coupling effect of defect parameters and corrosion degree on hydrogen permeation behavior is analyzed.

[0053] This invention includes the following steps:

[0054] Step S1: Obtain the initial simulation parameters through corrosion experiments;

[0055] Step S2: Construct the physical field coupling of current distribution and mass transfer using finite element software;

[0056] Step S3: Analyze the impact of sulfate-reducing bacteria corrosion on the hydrogen concentration distribution in defective pipelines.

[0057] Step S1, obtaining the initial simulation parameters, specifically includes the following steps;

[0058] Furthermore, the method for obtaining the initial simulation parameters in step S1 is as follows:

[0059] Step S11: Select a pipeline steel sample with the same material as the actual pipeline, and process the sample size to meet the requirements of hydrogen permeation and dynamic polarization tests;

[0060] Step S12: Pre-treat the sample by grinding, cleaning, dehydration and drying in sequence to remove oxide scale, oil and impurities from the sample surface and ensure that the sample surface is uniform.

[0061] Step S13: Construct a sulfate-reducing bacteria corrosion system, prepare a simulation solution to simulate the actual service environment, inoculate the target sulfate-reducing bacteria, and control the corrosion environment parameters;

[0062] Step S14: Place the pretreated sample in a sulfate-reducing bacteria corrosion system and conduct a corrosion experiment. The corrosion time is determined based on the actual service life of the pipeline.

[0063] Step S15: After the corrosion experiment, the hydrogen permeation current density-time curve and polarization curve were measured using the electrochemical hydrogen charging test method and the dynamic polarization test method.

[0064] Step S16: Obtain the cathodic and anodic Tafel slopes (b) of the corrosion experiment by fitting polarization curves. a b c ), and the exchange current density of the cathode and anode (I 0a I 0c ), corrosion current density (I) corr );

[0065] Step S17: Process the hydrogen permeation current density time-time curve using a constant concentration model to obtain the surface hydrogen concentration (C0) and hydrogen diffusion coefficient (D). eff ), hydrogen permeation flux (J).

[0066] Furthermore, the method for constructing the multiphysics coupling model in step S2 is as follows:

[0067] Step S21: Establish a physical model: Based on the actual pipe size parameters, establish a suitable pipe model with defects and define it as the metal domain. Construct a sulfate-reducing bacteria corrosion environment to simulate the service of the pipe and define it as the electrolyte domain. The contact surface between the electrolyte domain and the metal domain is the electrode surface.

[0068] Step S22: Configure the physical field: Add an electrochemical physical field to the metal domain to simulate the anodic dissolution reaction and cathodic reduction reaction in the corrosion process. Add a mass transfer physical field to the entire physical model to describe the diffusion, convection and migration processes of substances such as hydrogen ions and sulfate ions in the electrolyte domain and the diffusion of hydrogen atoms in the metal domain.

[0069] Step S23: Set up multi-physics coupling relationship: The substances consumed or generated by the electrochemical reaction are replenished or diffused through the mass transfer process, affecting the corrosion reaction; at the same time, the change in the concentration of substances during the mass transfer process will change the rate and distribution of the electrochemical reaction, thereby affecting the generation and penetration of hydrogen.

[0070] The coupling relationship is specifically constructed using the following formula:

[0071] The core formula for the electrochemical physical field was determined through corrosion reaction kinetics: the Butler-Volmer equation was used to describe the electrode reaction rate. This equation is the core equation characterizing the relationship between electrochemical reaction current density and overpotential, and its specific form is as follows:

[0072]

[0073] In the formula, I is the corrosion current density (A / m). 2 I0 is the exchange current density (A / m). 2 (from the experimental determination in step S15). , These are the cathode and anode transfer coefficients, respectively (which can be obtained using empirical values ​​or experimental fitting, and are usually taken as 0.5), and F is the Faraday constant (a fixed value of 96485 C / mol). R is the overpotential (V), R is the gas constant (fixed value 8.314 J / (mol·K)), and T is the absolute temperature (K, which is the control temperature of the sulfate-reducing bacteria corrosion simulation experiment in step S14).

[0074] The core formula of the physical field for mass transfer is determined by "concentration diffusion + migration": The Nernst-Planck equation is used to describe the transfer process of key substances (such as H⁺, SO₄²⁻, etc.) in corrosive liquids, covering three transfer forms: diffusion, migration and convection, as follows.

[0075]

[0076] In the formula: C i Let D be the concentration of substance i (mol / m³), t be time (s), and D be the concentration of substance i (mol / m³). i Z represents the diffusion coefficient of substance i (m² / s, which can be determined experimentally or obtained by consulting relevant literature). i Let be the charge number of substance i. R is the electrode potential (V, obtained from the electrochemical physical field), v is the solution flow rate (m / s, taken as 0 in static corrosion experiments), and R is the electrode potential (V, obtained from the electrochemical physical field). i The generation / consumption rate of substance i (mol / (m³·s)) is a key parameter for realizing the coupling of electrochemistry and mass transfer, and is derived from the electrochemical reaction rate.

[0077] Electrochemical-mass transport coupling correlation, the specific correlation is as follows:

[0078]

[0079] In the formula: n is the number of electrons transferred in the electrochemical reaction, and different electrode reactions correspond to different n values;

[0080] The specific relationship between the reaction transported by the reactants and the electrochemical kinetic parameters is as follows:

[0081]

[0082] In the formula, C i , The concentration of substance i at the solution and at the electrode surface (mol / m³, determined by the mass transfer process in the solution).

[0083] Coupling formula for hydrogen atoms penetrating into metals:

[0084]

[0085] In the formula, k1 is the ratio of hydrogen atoms penetrating into the metal to the total hydrogen atoms produced by the cathode reaction (calculated from the corrosion current density and surface hydrogen atom concentration obtained in step S1), I c Cathode current density (A / m) 2 ).

[0086] Step S24: Input the key hydrogen permeation parameters and corrosion-related parameters obtained in step S1 into the model as the initial parameters and material properties of the coupled model.

[0087] Furthermore, the method for analyzing the hydrogen concentration distribution in the pipeline in step S3 is as follows:

[0088] Step S31: Solve the multiphysics coupling model, run the solution module of the finite element software, solve the coupling equation, and obtain numerical simulation results such as hydrogen concentration distribution cloud map, hydrogen concentration gradient distribution and hydrogen permeation flux distribution of defective pipelines under different corrosion times and different sulfate-reducing bacteria corrosion degrees.

[0089] Step S32: Verify the accuracy of the simulation results. Conduct sulfate-reducing bacteria corrosion and hydrogen permeation experiments on defective pipelines to measure the actual corrosion current density and hydrogen permeation flux. Compare the results with the numerical simulation results and correct the model parameters (such as hydrogen diffusion coefficient, boundary conditions, etc.) to ensure the reliability of the simulation results.

[0090] Step S33: Analyze the influence of sulfate-reducing bacteria corrosion degree on hydrogen concentration distribution. Keeping other parameters constant, change parameters such as sulfate-reducing bacteria concentration and corrosion time to simulate different corrosion degrees. Compare the hydrogen concentration distribution characteristics of the defect area and surrounding area under different corrosion degrees to reveal the intrinsic relationship between sulfate-reducing bacteria corrosion degree and hydrogen concentration peak and hydrogen concentration gradient. Analyze the coupling effect of defect parameters such as defect size, depth, and shape with sulfate-reducing bacteria corrosion degree on hydrogen permeation behavior, providing a theoretical basis for corrosion protection and safety assessment of defective pipelines.

[0091] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the scope of the present invention. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A numerical simulation method for hydrogen permeation in defective pipelines affected by sulfate-reducing bacteria corrosion, characterized in that, Specifically, the following steps are included: Step S1: Obtain the initial simulation parameters through corrosion experiments; Step S2: Construct a coupled physical field model of current distribution and mass transfer using finite element software; Step S3: Analyze the impact of sulfate-reducing bacteria corrosion on the hydrogen concentration distribution in defective pipelines.

2. The method according to claim 1, characterized in that, Step S1, obtaining the initial simulation parameters, specifically includes the following steps: Step S11: Select a pipeline steel sample with the same material as the actual pipeline, and process the sample size to meet the requirements of hydrogen permeation and dynamic polarization tests; Step S12: Pre-treat the sample by grinding, cleaning, dehydration and drying in sequence to remove oxide scale, oil and impurities from the sample surface and ensure that the sample surface is uniform. Step S13: Construct a sulfate-reducing bacteria corrosion system, prepare a simulation solution to simulate the actual service environment, inoculate the target sulfate-reducing bacteria, and control the corrosion environment parameters; Step S14: Place the pretreated sample in a sulfate-reducing bacteria corrosion system and conduct a corrosion experiment. The corrosion time is determined based on the actual service life of the pipeline. Step S15: After the corrosion experiment, the hydrogen permeation current density-time curve and polarization curve were measured using the electrochemical hydrogen charging test method and the dynamic polarization test method. Step S16: Obtain the Tafel slope b of the cathode and anodic axes in the corrosion experiment by fitting the polarization curve. a b c The exchange current density I between the cathode and anode 0a I 0c Corrosion current density I corr ; Step S17: Process the hydrogen permeation current density time-time curve using a constant concentration model to obtain the surface hydrogen concentration C0 and hydrogen diffusion coefficient D. eff Hydrogen permeation flux J.

3. The method according to claim 1, characterized in that, The method for constructing the physical field coupling model of current distribution and mass transport described in step S2 includes: Step S21: Establish a physical model: Based on the actual pipe size parameters, establish a suitable pipe model with defects and define it as the metal domain. Construct a sulfate-reducing bacteria corrosion environment to simulate the service of the pipe and define it as the electrolyte domain. The contact surface between the electrolyte domain and the metal domain is the electrode surface. Step S22: Configure the physical field: Add an electrochemical physical field to the metal domain to simulate the anodic dissolution reaction and cathodic reduction reaction in the corrosion process. Add a mass transfer physical field to the entire physical model to describe the diffusion, convection and migration processes of substances such as hydrogen ions and sulfate ions in the electrolyte domain and the diffusion of hydrogen atoms in the metal domain. Step S23: Set up multi-physics coupling relationship: The substances consumed or generated by the electrochemical reaction are replenished or diffused through the mass transfer process, affecting the corrosion reaction; at the same time, the change in the concentration of substances during the mass transfer process will change the rate and distribution of the electrochemical reaction, thereby affecting the generation and penetration of hydrogen. Step S24: Input the key hydrogen permeation parameters and corrosion-related parameters obtained in step S1 into the model as the initial parameters and material properties of the coupled model.

4. The method according to claim 3, characterized in that, Step S23 specifically establishes the coupling relationship through the following formula: The core formula for the electrochemical physical field was determined through corrosion reaction kinetics: the Butler-Volmer equation was used to describe the electrode reaction rate. This equation is the core equation characterizing the relationship between electrochemical reaction current density and overpotential, and its specific form is as follows: In the formula, I is the corrosion current density A / m 2 ; I0 is the exchange current density. , These are the cathode and anode transfer coefficients, respectively, where F is the Faraday constant. V is the overpotential, R is the gas constant, T is the absolute temperature K, and K is the control temperature of the sulfate-reducing bacteria corrosion simulation experiment in step S14. The core formula for the physical field of mass transfer is determined by "concentration diffusion + migration": The Nernst-Planck equation is used to describe the transfer process of key substances (such as H⁺, SO₄²⁻, etc.) in corrosive solutions, covering three transfer modes: diffusion, migration, and convection, as follows: In the formula: C i Let D be the concentration of substance i in mol / m³, t be time in seconds, and D be the concentration of substance i in mol / m³. i Let m² / s be the diffusion coefficient of substance i, and z be the diffusion coefficient of substance i. i Let be the charge number of substance i. R is the electrode potential V, v is the solution flow rate in m / s, and R is the electrode potential. i Let be the rate of formation / consumption of substance i in mol / (m³·s); Electrochemical-mass transport coupling correlation, the specific correlation is as follows: In the formula: n is the number of electrons transferred in the electrochemical reaction, and different electrode reactions correspond to different n values; The specific relationship between the reaction transported by the reactants and the electrochemical kinetic parameters is as follows: In the formula, C i , Let be the concentration of substance i in solution and at electrode surface, in mol / m³. Coupling formula for hydrogen atoms penetrating into metals: In the formula, k1 is the ratio of hydrogen atoms that permeate into the metal to the total hydrogen atoms produced by the cathode reaction, and I c Cathode current density A / m 2 .

5. The method according to claim 1, characterized in that, Step S3, analyzing the impact of sulfate-reducing bacterial corrosion on the hydrogen concentration distribution in defective pipelines, specifically includes the following steps: Step S31: Solve the multiphysics coupling model, run the solution module of the finite element software, solve the coupling equation, and obtain numerical simulation results such as hydrogen concentration distribution cloud map, hydrogen concentration gradient distribution and hydrogen permeation flux distribution of defective pipelines under different corrosion times and different sulfate-reducing bacteria corrosion degrees. Step S32: Verify the accuracy of the simulation results. Conduct sulfate-reducing bacteria corrosion and hydrogen permeation experiments on defective pipelines, measure the actual corrosion current density and hydrogen permeation flux, compare them with the numerical simulation results, correct the model parameters, and ensure the reliability of the simulation results. The model parameters include hydrogen diffusion coefficient and boundary conditions. Step S33: Analyze the influence of sulfate-reducing bacteria corrosion degree on hydrogen concentration distribution. Keeping other parameters constant, change parameters such as sulfate-reducing bacteria concentration and corrosion time to simulate different corrosion degrees. Compare the hydrogen concentration distribution characteristics of the defect area and surrounding area under different corrosion degrees to reveal the intrinsic relationship between sulfate-reducing bacteria corrosion degree and hydrogen concentration peak and hydrogen concentration gradient. Analyze the coupling effect of defect parameters such as defect size, depth, and shape with sulfate-reducing bacteria corrosion degree on hydrogen permeation behavior, providing a theoretical basis for corrosion protection and safety assessment of defective pipelines.

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