A method and system for evaluating and grading the safety of internal corrosion of an oil pipeline and preventing and controlling the same

Abstract

The application discloses a kind of oil pipeline internal corrosion safety evaluation and grading prevention and control method and system, the method includes: the wall thickness detection data of pipeline each measuring point, corrosion rate data and several environmental and operating parameters are collected;Wall thickness detection data is subjected to wall thickness thinning safety grade determination processing, and first dimension evaluation result is obtained;According to corrosion rate data combined with several environmental and operating parameters, corrosion comprehensive risk correction assessment processing is carried out, and second dimension evaluation result is obtained;First dimension evaluation result and second dimension evaluation result are subjected to two-dimension collaborative decision processing based on, and the internal corrosion safety grading prevention and control strategy of pipeline is obtained.The application can improve the accuracy of pipeline internal corrosion safety evaluation.The application can be widely applied to corrosion safety prevention and control technical field as a kind of oil pipeline internal corrosion safety evaluation and grading prevention and control method and system.

Description

Technical Field

[0001] This invention relates to the field of corrosion safety control technology, and in particular to a method and system for corrosion safety assessment and graded control in oil pipelines. Background Technology

[0002] Pipelines play a vital role in the transportation of energy resources such as oil and natural gas. Under intermittent operating conditions (such as the inbound and outbound pipelines of national strategic oil reserves), pipelines are in a state of long-term media stagnation, causing corrosive media to accumulate at the bottom of the pipeline, exacerbating water-oil stratification, and significantly increasing the risk of localized pitting corrosion and wall thinning.

[0003] However, existing risk-based inspection (RBI) methods have limited accuracy in predicting corrosion trends under intermittent operating conditions. For example, a method and apparatus for quantitatively assessing the failure risk of oil and gas gathering and transportation pipelines suffers from the following technical problems: 1) The evaluation dimensions are limited, providing only a failure risk assessment and failing to address the structural safety assessment dimension of wall thickness reduction. This makes it impossible to distinguish between the pipeline's "current safety" (accumulated wall thickness damage already occurred) and "future risk" (corrosion development trend), two independent engineering judgments. Wall thickness reduction reflects the degree of accumulated corrosion damage already occurred and is the fundamental basis for deciding whether immediate repair is necessary; corrosion risk reflects the likelihood of continued corrosion development in the future and is the basis for guiding monitoring frequency and corrosion inhibition strategies—both are indispensable in engineering decision-making, yet the relevant technology only covers the latter. 2) The correction factor is singular, using only slug flow risk as the sole correction factor. Pipeline corrosion is a complex process involving the coupling of multiple factors: Concentration determines the severity of pitting corrosion. Concentration affects the protective properties of the corrosion product film; the water-to-oil ratio determines the phase distribution and non-uniform corrosion intensity; flow rate affects the erosion and detachment of the product film; and temperature affects the electrochemical reaction rate. The partial pressure determines the driving force of acid corrosion, and the geometry of the elbow determines the local erosion amplification effect. The mechanisms of these seven factors are different and they often occur simultaneously in unfavorable combinations to form a superimposed amplification effect. However, the relevant technology only uses slug flow as a factor for correction, completely ignoring the influence of the other six key factors. 3) The evaluation and decision-making are disconnected. The relevant methods stop at outputting risk values / levels and do not provide a mechanism for connecting the evaluation results with specific prevention and control measures. After obtaining the risk level, the engineers still need to decide the monitoring frequency and intervention methods on their own. 4) Not suitable for intermittent operating conditions. The relevant methods use slug flow risk as the only correction factor, implicitly assuming that the pipeline is in continuous flow condition (slug flow itself is a flow state). Its evaluation framework is naturally not suitable for intermittently operating pipelines where the medium is stationary for a long time. Summary of the Invention

[0004] To address the aforementioned technical problems, the present invention aims to provide a method and system for corrosion safety assessment and graded prevention and control within oil pipelines, which can improve the accuracy of corrosion safety assessment within pipelines.

[0005] The first technical solution adopted in this invention is: a method for safety assessment and graded prevention of corrosion in oil pipelines, comprising the following steps: Collect wall thickness detection data, corrosion rate data, and several environmental and operational parameters at various measuring points along the pipeline. The wall thickness detection data is processed to determine the safety level of wall thickness reduction, and the first dimension evaluation result is obtained. Based on corrosion rate data and several environmental and operational parameters, a comprehensive corrosion risk correction assessment was performed to obtain the second-dimensional evaluation results. Based on the evaluation results of the first and second dimensions, a two-dimensional collaborative decision-making process is performed to obtain a safety classification and prevention strategy for pipeline corrosion.

[0006] Furthermore, the wall thickness detection data specifically includes the minimum remaining wall thickness and the original wall thickness, and the environmental and operating parameters specifically include chloride ion concentration, sulfur ion concentration, water-oil ratio, medium flow rate, temperature, carbon dioxide partial pressure, and elbow geometry.

[0007] Furthermore, the first dimension evaluation result includes a first-level wall thickness reduction safety level, a second-level wall thickness reduction safety level, a third-level wall thickness reduction safety level, and a fourth-level wall thickness reduction safety level. The step of processing the wall thickness detection data to determine the wall thickness reduction safety level and obtain the first dimension evaluation result specifically includes: Obtain the ratio of the minimum remaining wall thickness to the original wall thickness, and determine the wall thickness ratio. If the wall thickness ratio is greater than the first preset wall thickness ratio threshold, it is determined to be the first level of wall thickness reduction safety level; If the wall thickness ratio is greater than the second preset wall thickness ratio threshold and less than or equal to the first preset wall thickness ratio threshold, it is determined to be the second level of wall thickness reduction safety level. If the wall thickness ratio is greater than the third preset wall thickness ratio threshold and less than or equal to the second preset wall thickness ratio threshold, it is determined to be the third level of wall thickness reduction safety level. If the wall thickness ratio is not greater than the third preset wall thickness ratio threshold or the minimum remaining wall thickness is not greater than the preset minimum wall thickness threshold, it is determined to be the fourth level of wall thickness reduction safety level.

[0008] Furthermore, the step of performing a comprehensive corrosion risk correction assessment based on corrosion rate data combined with several environmental and operational parameters to obtain the second-dimensional evaluation result specifically includes: The corrosion rate data is processed to determine the basic risk level, thus obtaining the basic risk level. Several environmental and operational parameters are individually corrected and scored to obtain a cumulative correction score. The basic risk level is adjusted based on the cumulative correction score to obtain the final comprehensive corrosion risk level, and the second dimension evaluation result is output.

[0009] Furthermore, the basic risk level includes a first-level basic risk level, a second-level basic risk level, a third-level basic risk level, and a fourth-level basic risk level. The step of determining the basic risk level by processing the corrosion rate data specifically includes: If the corrosion rate data is less than the first preset corrosion rate threshold, it is determined to be the first level of basic risk. If the corrosion rate data is greater than or equal to the first preset corrosion rate threshold and less than the second preset corrosion rate threshold, it is determined to be the second level of basic risk. If the corrosion rate data is greater than or equal to the second preset corrosion rate threshold and less than the third preset corrosion rate threshold, it is determined to be a level three basic risk level. If the corrosion rate data is greater than or equal to the third preset corrosion rate threshold, it is determined to be a level four basic risk level.

[0010] Furthermore, the step of performing itemized correction scoring on several environmental and operational parameters to obtain a cumulative correction score specifically includes: For each environmental and operational parameter, the measured value is matched with the corresponding preset multi-level parameter threshold to obtain the single correction score for each parameter. The cumulative correction score is obtained by summing up all individual correction scores.

[0011] Furthermore, the step of adjusting the basic risk level based on the cumulative correction score to obtain the final comprehensive corrosion risk level specifically includes: If the cumulative correction score is greater than or equal to the first preset score threshold, the current basic risk level will be raised by two levels. If the cumulative correction score is greater than or equal to the second preset score threshold and less than the first preset score threshold, the current basic risk level will be raised by one level. If the cumulative corrected score is less than the second preset score threshold, the current basic risk level will remain unchanged. If the current basic risk level is already at Level 4, it will not be upgraded further.

[0012] Furthermore, the step of performing dual-dimensional collaborative decision-making based on the first-dimensional evaluation results and the second-dimensional evaluation results to obtain the pipeline corrosion safety classification and prevention strategy specifically includes: If the current wall thickness reduction safety level reaches the preset structural intervention level, the structural intervention strategy will be output first, and the current comprehensive corrosion risk level will be used as an auxiliary basis for corrosion cause analysis and operation plan optimization. If the current wall thickness reduction safety level does not reach the preset structural intervention level, output corrosion monitoring and control measures of corresponding intensity based on the current comprehensive corrosion risk level.

[0013] Furthermore, the step of outputting corrosion monitoring and control measures of corresponding intensity based on the current comprehensive corrosion risk level specifically includes: If the risk level is Level 1, routine monitoring will be conducted and a corrosion trend report will be submitted according to the first preset cycle. If it is the second level of basic risk, then intensified monitoring will be carried out, and the corrosion rate and thinning thickness will be evaluated according to the second preset cycle. If the risk level is Level 3, enhanced monitoring will be implemented, and the corrosion rate and thinning thickness will be evaluated according to the third preset cycle. Online corrosion monitoring will be added and the corrosion inhibitor injection scheme will be optimized. If the risk level is Level 4, continuous monitoring will be conducted to track the corrosion rate and thinning thickness in real time. The corrosion inhibitor strategy will be adjusted immediately, and corrosion trend analysis will be submitted according to the fourth preset cycle.

[0014] The second technical solution adopted in this invention is: a corrosion safety assessment and classification prevention system for oil pipelines, comprising: The first module is used to collect wall thickness detection data, corrosion rate data, and several environmental and operational parameters at various measuring points in the pipeline. The second module is used to process the wall thickness detection data to determine the safety level of wall thickness reduction, and obtain the first dimension evaluation result. The third module is used to perform a comprehensive corrosion risk correction assessment based on corrosion rate data and several environmental and operational parameters to obtain the second-dimensional evaluation results. The fourth module is used for two-dimensional collaborative decision-making based on the evaluation results of the first and second dimensions to obtain a pipeline corrosion safety classification and prevention strategy.

[0015] The beneficial effects of the method and system of this invention are as follows: This invention collects wall thickness detection data, corrosion rate data, and several environmental and operational parameters from various measuring points in the pipeline, incorporating key influencing factors into a unified quantitative correction framework. This framework covers four major categories of factors: chemical environment, phase distribution, flow characteristics, and geometric structure, thereby improving the comprehensiveness and accuracy of the evaluation and effectively reflecting the superimposed amplification effect when multiple factors are simultaneously unfavorable. Furthermore, the wall thickness detection data is processed to determine the safety level of wall thickness reduction, yielding the first-dimensional evaluation result. Further, based on the corrosion rate data and several environmental and operational parameters, a comprehensive corrosion risk correction assessment is performed to obtain the second-dimensional... The evaluation results are directly transformed into a four-level differentiated prevention and control strategy. Finally, based on the evaluation results of the first and second dimensions, a two-dimensional collaborative decision-making process is carried out to obtain a graded prevention and control strategy for pipeline corrosion safety. By establishing a two-dimensional comprehensive evaluation system of wall thickness reduction safety evaluation and comprehensive corrosion risk evaluation, the wall thickness reduction safety evaluation is used as the fundamental basis for structural intervention decision-making, and the comprehensive corrosion risk evaluation is used as the guiding basis for corrosion control intensity. The two dimensions are evaluated independently and made collaboratively, which fills the gap in the existing technology where structural safety evaluation and corrosion risk evaluation are separated, and improves the accuracy of pipeline corrosion safety evaluation. Attached Figure Description

[0016] Figure 1 This is a flowchart of the steps of a method for safety assessment and graded prevention and control of corrosion in oil pipelines according to the present invention; Figure 2 This is a structural block diagram of a corrosion safety assessment and graded prevention and control system for oil pipelines according to the present invention; Figure 3 This is a schematic diagram of the system architecture framework provided in a specific embodiment of the present invention; Figure 4 This is a schematic diagram illustrating the threshold division of wall thickness reduction safety levels provided in a specific embodiment of the present invention; Figure 5 This is a schematic diagram of the basic risk level threshold for corrosion rate provided in a specific embodiment of the present invention; Figure 6 This is a schematic diagram of a two-dimensional collaborative decision matrix provided in a specific embodiment of the present invention. Detailed Implementation

[0017] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. The step numbers in the following embodiments are only for ease of explanation and do not limit the order of the steps. The execution order of each step in the embodiments can be adapted according to the understanding of those skilled in the art.

[0018] First, it should be noted that this invention establishes a two-dimensional comprehensive evaluation system consisting of a wall thickness reduction safety assessment and a comprehensive corrosion risk assessment. The former determines structural intervention (whether repair or replacement is necessary), while the latter determines the intensity of corrosion control (monitoring frequency and corrosion inhibition strategies). The comprehensive corrosion risk assessment introduces a "baseline level + seven-factor auxiliary correction" mechanism, which is the first systematic approach to... Concentration, Concentration, water-to-oil ratio, medium flow rate, temperature Seven key influencing factors, including pressure distribution and elbow geometry, are incorporated into a unified quantitative correction framework. Each factor has a clear quantitative threshold and correction score. The scientific quantification of the coupling effect of multiple factors is achieved through cumulative scoring. Ultimately, the evaluation results are directly transformed into a four-level differentiated prevention and control strategy, forming a closed-loop management of "evaluation-decision-implementation".

[0019] Reference Figure 1 This invention provides a method for corrosion safety assessment and graded prevention and control in oil pipelines, the method comprising the following steps: S100: Collect wall thickness detection data, corrosion rate data, and several environmental and operational parameters at various measuring points along the pipeline. In this embodiment, wall thickness detection data, corrosion rate data, and seven environmental and operational parameters are collected at various measuring points along the pipeline. The wall thickness detection data includes the minimum remaining wall thickness. and original wall thickness The environmental and operating parameters include concentration, Concentration, water-to-oil ratio, medium flow rate, temperature Pressure distribution and elbow geometry.

[0020] This study focuses on a Φ711 crude oil pipeline located outside the underground storage area of ​​a national strategic oil reserve. The pipeline is 2.82 km long and operates under intermittent conditions, meaning it is long-term stationary with periodic oil delivery and receipt. An internal corrosion safety assessment and control strategy were developed at four representative monitoring points along the pipeline, with an assessment period of 25 years. Wall thickness data was obtained at each monitoring point using an ultrasonic thickness gauge to determine the minimum remaining wall thickness. Measurement points 1 to 4 They are 0.995T0, 0.997T0, 0.996T0, and 0.999T0, respectively. This represents the original wall thickness, i.e., the design wall thickness of the Φ711 pipe. Corrosion rate data were obtained through a full immersion test with corrosion-resistant inserts. The corrosion rates (CR) at the four measuring points were 0.0158 mm / a, 0.0092 mm / a, 0.0125 mm / a, and 0.00117 mm / a, respectively. Environmental and operational parameters were obtained through online sensors and laboratory analysis. The concentration was 6.57 mg / kg. The concentration is 3.27 wt%, the water-to-oil ratio is 3 vol%, the medium flow rate is 0 (the medium is in a static state), and the temperature is 28℃. Pressure distribution was not detected (the medium in the pipeline was crude oil). (The content is negligible), the geometry of the elbow is obtuse, but the medium is stationary and there is no scouring.

[0021] S200. Perform wall thickness reduction safety level determination processing on the wall thickness detection data to obtain the first dimension evaluation result; Specifically, the ratio of the minimum remaining wall thickness to the original wall thickness is obtained to determine the wall thickness ratio. If the wall thickness ratio is greater than the first preset wall thickness ratio threshold, it is determined to be at the first level of wall thickness reduction safety level. If the wall thickness ratio is greater than the second preset wall thickness ratio threshold and less than or equal to the first preset wall thickness ratio threshold, it is determined to be at the second level of wall thickness reduction safety level. If the wall thickness ratio is greater than the third preset wall thickness ratio threshold and less than or equal to the second preset wall thickness ratio threshold, it is determined to be at the third level of wall thickness reduction safety level. If the wall thickness ratio is not greater than the third preset wall thickness ratio threshold or the minimum remaining wall thickness is not greater than the preset minimum wall thickness threshold, it is determined to be at the fourth level of wall thickness reduction safety level.

[0022] In this embodiment, the rule for determining the safety level of wall thickness reduction based on the range of the ratio is as follows: when Continue to use if it is Level I; when At that time, it was Level II enhanced monitoring; when At that time, it was a Level III planned maintenance; when or The requirement is Level IV for immediate repair; the wall thickness reduction safety level directly reflects the current structural integrity of the pipeline.

[0023] Calculate the wall thickness ratio at four measuring points Measuring point 1 is 0.995, measuring point 2 is 0.997, measuring point 3 is 0.996, and measuring point 4 is 0.999. The wall thickness ratios at all four measuring points meet the requirements. The conditions, according to the judgment rules, Continue to use at Level I At the time, it was a Level II enhanced monitoring system. At that time, it was a Level III planned maintenance. or The initial requirement was Level IV for immediate repair, while the wall thickness reduction safety level at all four measuring points was Level I. This result directly indicates that the pipeline structure remains intact under current service conditions, with ample safety margin for wall thickness, eliminating the need for structural intervention measures such as repair or replacement.

[0024] S300. Based on corrosion rate data and several environmental and operational parameters, a comprehensive corrosion risk correction assessment is performed to obtain the second-dimensional evaluation result. S310. Perform basic risk level determination processing on the corrosion rate data to obtain the basic risk level; Specifically, the rule for determining the basic risk level based on corrosion rate data is as follows: when the corrosion rate... When the rate is low, it is classified as Level I, low risk; when At that time, it was classified as Level II, medium risk; when At that time, it was classified as Level III high risk; when The risk level is Class IV, which is extremely high. The threshold for the corrosion rate is determined with reference to the NACE SP0775 standard and in combination with the distribution of corrosion data measured under intermittent operating conditions.

[0025] Corrosion rate at four measuring points All were below the Class I threshold of 0.025 mm / a (CR values ​​were 0.0158, 0.0092, 0.0125, and 0.00117 mm / a, respectively). According to the judgment rules, Level I low risk Level II medium risk Level III high risk The risk level is classified as Level IV (extremely high), while the basic risk level for all four measuring points is Level I (low risk). The corrosion rate grading thresholds are based on the NACE SP0775 international standard for defining corrosion severity, and have been appropriately refined using the distribution range of measured corrosion data (0.009~0.3015 mm / a) under intermittent operating conditions in this embodiment. This ensures consistency with international standards while accurately reflecting the actual corrosion rate gradient under these conditions. The basic risk level reflects the likelihood and severity of continued corrosion development during future pipeline operation.

[0026] S320. Perform itemized correction scoring on several environmental and operational parameters to obtain the cumulative correction score; Specifically, the correction scoring rules for each of the seven environmental and operational parameters are as follows: 1) Concentration Correction Fraction For doses >20 mg / kg, take 1.0; for doses between 9 and 20 mg / kg, take 0.5; for doses <9 mg / kg, take 0. 2) Concentration Correction Fraction For >5.5wt%, take 1.0; for 2~5.5wt%, take 0.5; for <2wt%, take 0. 3) Water-oil ratio correction fraction Take 1.0 for 50~75 vol%, 0.5 for 20~50 vol% or 75~100 vol%, and 0 for <25 vol%. 4) Medium flow rate correction fraction For speeds >5 m / s, take 1.0; for speeds 2~5 m / s, take 0.5; for speeds <2 m / s, take 0. 5) Temperature correction fraction For temperatures >80℃, use 1.0; for temperatures between 40 and 80℃, use 0.5; for temperatures <40℃, use 0. 6) Partial pressure correction fraction For pressures >0.2MPa, use 1.0; for pressures between 0.1 and 0.2MPa, use 0.5; for pressures <0.1MPa, use 0. 7) Elbow geometry correction fraction For acute-angle right-angle bends, use 1.0; for obtuse-angle bends, use 0.5; for straight pipes without bends, use 0. The cumulative corrected score is .

[0027] In this embodiment, taking measurement point 1 as an example, the correction score is evaluated item by item: The concentration was 6.57 mg / kg, falling within the <9 mg / kg range (slight pitting corrosion), correction fraction. ; The concentration was 3.27 wt%, falling within the range of 2–5.5 wt% (significant pitting corrosion, increased corrosion rate), correction fraction. ; The water-to-oil ratio is 3 vol%, falling within the <25 vol% range (uniform corrosion), correction fraction. ; The medium flow velocity is 0 m / s (stationary state, no erosion), falling within the <2 m / s range (weak erosion), correction fraction. ; The temperature is 28℃, falling within the <40℃ range (temperature has a relatively small impact on the corrosion rate), correction fraction. ; Pressure distribution was not detected; the medium inside the pipeline is crude oil. The content is negligible, so it is not counted in the score, which is a correction score. ; Although the elbow geometry is an obtuse angle elbow, the crude oil medium inside the pipeline is in a static state and is not affected by erosion. There is no additional erosion caused by geometric abrupt changes, so the correction fraction is corrected. .

[0028] Cumulative Correction Score The environmental and operating parameters for the other three measuring points are the same as those for measuring point 1, and the cumulative correction score for each is 0.5. The thresholds for each correction index are selected based on a clearly defined corrosion mechanism: and The high-risk range corresponds to the turning point where pitting corrosion develops from obvious to severe; the high-risk range of water-oil ratio is in the range where the oil-water two-phase distribution is most unstable; the high-risk threshold of flow velocity corresponds to the critical flow velocity at which the product film begins to be washed away and the flow velocity at which the erosion effect is strongest; the temperature is the temperature at which the corrosion rate of most pipeline steel reaches its peak as the high-risk boundary. The pressure distribution is consistent with the industry-recognized standard for severe corrosion; among the geometric shapes of elbows, the acute-angle turning elbows have the strongest erosion due to the drastic change in flow channel and the long residence time of particles.

[0029] S330. Adjust the basic risk level according to the cumulative correction score to obtain the final comprehensive corrosion risk level and output the second dimension evaluation result.

[0030] Specifically, the rule for adjusting the basic risk level according to the preset adjustment rules is as follows: when When, the level is raised by two levels but not exceeding Level IV; when At that time, the level shall be raised by one level but not exceeding level IV; The level remains unchanged; when The risk level remains unchanged; if the basic risk level is already at level IV, it will not be upgraded further.

[0031] Cumulative Correction Score ,satisfy Based on the conditions and preset adjustment rules, The level is raised by two levels but not exceeding Level IV. The level is raised by one level but not exceeding level IV. The risk level remains unchanged. The final comprehensive corrosion risk level for all four measuring points is Level I (low risk). When multiple adverse factors exist simultaneously, the risk has a cumulative effect; therefore, the risk level is increased cumulatively for each independent condition met. When none of the factors reach the correction threshold, the level remains unchanged. This ensures that the rules can reasonably reflect the risk amplification effect under the coupling effect of multiple factors, while avoiding erroneous upward adjustment when there are no risk factors.

[0032] S400, based on the evaluation results of the first dimension and the evaluation results of the second dimension, performs two-dimensional collaborative decision-making to obtain the pipeline corrosion safety classification and prevention strategy.

[0033] Specifically, a two-dimensional collaborative decision-making process is adopted, taking into account both the safety level of wall thickness reduction and the comprehensive corrosion risk level. Priority is given to determining whether structural intervention is needed based on the safety level of wall thickness reduction, and then the degree of strengthening of corrosion monitoring and prevention is determined based on the comprehensive corrosion risk level, resulting in a graded prevention and control strategy.

[0034] In this embodiment, the specific rules for dual-dimensional collaborative decision-making are as follows: when the wall thickness reduction safety level is Level III or Level IV, structural intervention recommendations are the primary consideration, including planned maintenance or immediate maintenance, and the comprehensive corrosion risk level is used as auxiliary information to analyze the causes of corrosion and optimize subsequent operation plans; when the wall thickness reduction safety level is Level I or Level II, differentiated prevention and control measures are directly output according to the comprehensive corrosion risk level.

[0035] The differentiated prevention and control measures are classified according to the comprehensive corrosion risk level as follows: For Level I, routine monitoring is conducted, and an annual corrosion trend report is submitted. For Level II, intensified monitoring is implemented, with corrosion rate and thinning thickness evaluated every six months. For Level III, the corrosion rate and thinning thickness are evaluated quarterly, online corrosion monitoring is increased, and the corrosion inhibitor injection scheme is optimized. For Level IV, continuously monitor corrosion rate and thinning thickness, immediately adjust corrosion inhibitor strategy, and submit corrosion trend analysis weekly; all measures are managed in a closed loop, and relevant records are archived for future reference.

[0036] All four measuring points have a wall thickness reduction safety level of Class I (no structural intervention required) and a comprehensive corrosion risk level of Class I (low risk). The wall thickness reduction safety level directly reflects the current structural integrity of the pipeline and is the fundamental basis for determining whether to take structural intervention measures such as planned maintenance or immediate replacement. The comprehensive corrosion risk level reflects the possibility and severity of continued corrosion development in the pipeline's future operation and is mainly used to guide corrosion control and prevention measures such as monitoring frequency, corrosion inhibitor strategies, and early warning mechanisms. The two are not interchangeable and should not overlap.

[0037] According to the dual-dimensional collaborative decision-making rule: when the wall thickness reduction safety level is Level I, differentiated prevention and control measures are directly output based on the comprehensive corrosion risk level. The prevention and control measures corresponding to a comprehensive corrosion risk level of Level I are: routine monitoring, annual corrosion trend report submission, and maintaining the existing operation and monitoring plan. When the wall thickness reduction safety level reaches Level III or IV, requiring pressure reduction or maintenance, the comprehensive corrosion risk level is used as supplementary information to analyze the causes of corrosion and optimize subsequent operation plans; when the wall thickness reduction safety level is Level I or II, the degree of strengthening of monitoring and prevention is directly determined based on the comprehensive corrosion risk level. Level II corresponds to intensified monitoring, with corrosion rate and thinning thickness evaluated every six months; Level III corresponds to quarterly evaluation of corrosion rate and thinning thickness, with increased online corrosion monitoring and optimization of corrosion inhibitor injection plans; Level IV corresponds to continuous monitoring of corrosion rate and thinning thickness, immediate adjustment of corrosion inhibitor strategies, and weekly submission of corrosion trend analysis. All measures should form a closed-loop management system, and relevant records should be archived for future reference.

[0038] Through dual-dimensional evaluation and collaborative decision-making, both the safety of the pipeline itself is fully guaranteed, and the corrosion process can be effectively controlled. For the Φ711 crude oil pipeline in this embodiment, the comprehensive evaluation results of the four monitoring points show that it is currently in a low-risk state, and maintaining the conventional monitoring plan is sufficient.

[0039] This invention collects wall thickness and corrosion rate data from various measuring points along the pipeline, along with seven environmental and operational parameters. It calculates the ratio of the minimum remaining wall thickness to the original wall thickness to determine the safety level of wall thickness reduction, thus obtaining the first-dimensional evaluation result. Based on the corrosion rate, it determines the basic risk level, sequentially assigns corrected scores to the seven auxiliary factors according to quantified thresholds, and accumulates these scores. Adjustments are then made according to rules to obtain the final comprehensive corrosion risk level. A collaborative decision is made based on both dimensions, prioritizing the wall thickness reduction safety level to determine whether structural intervention is necessary, and then matching four levels of differentiated prevention and control measures based on the comprehensive corrosion risk level. This invention establishes a two-dimensional comprehensive evaluation system and a fully closed-loop hierarchical prevention and control management system, which is particularly suitable for the internal corrosion safety evaluation and operation and maintenance decisions of oil pipelines operating under intermittent conditions.

[0040] In summary, the embodiments of the present invention have the following advantages compared with the prior art: 1) In terms of evaluation dimensions, this invention establishes a dual-dimensional comprehensive evaluation system comprising wall thickness reduction safety evaluation and corrosion risk assessment. The wall thickness reduction safety evaluation serves as the fundamental basis for structural intervention decisions, while the corrosion risk assessment serves as the guiding basis for corrosion control intensity. These two dimensions are evaluated independently and used in synergistic decision-making, filling the gap in existing technologies where structural safety evaluation and corrosion risk assessment are separated. Related technologies only provide a comprehensive risk value, failing to distinguish between the current structural integrity of the pipe section (cumulative wall thickness damage that has occurred) and the future corrosion development trend. This invention, however, simultaneously answers two independent engineering questions: "Is the pipeline safe now?" and "What is the future risk of the pipeline?"

[0041] 2) In terms of evaluation methodology, this invention, for the first time, utilizes a "benchmark level + seven-factor auxiliary correction" mechanism to... concentration, Concentration, water-to-oil ratio, medium flow rate, temperature Seven key influencing factors, including partial pressure and elbow geometry, are incorporated into a unified quantitative correction framework, covering four major categories of factors: chemical environment, phase distribution, flow characteristics, and geometric structure. Each factor has a clearly defined quantitative threshold based on corrosion mechanisms and a three-level correction score (0 / 0.5 / 1.0). The scientific quantification of the coupled effects of multiple factors is achieved through cumulative scoring. Compared to related technologies that only use slug flow risk as a single correction factor, this invention significantly improves the comprehensiveness and accuracy of the evaluation, effectively reflecting the superimposed amplification effect when multiple factors are simultaneously unfavorable.

[0042] 3) In terms of decision-making output, this invention directly transforms the evaluation results into a four-level differentiated prevention and control strategy, from Level I routine monitoring and annual reports to Level IV continuous monitoring plus adjustment of corrosion inhibitors plus weekly analysis, forming a closed-loop management covering all risk levels. This overcomes the shortcomings of related technologies, such as "evaluation is the endpoint, only evaluating and not managing." The evaluation rules are based on clear quantitative thresholds and cumulative calculations, without relying on complex model training. Engineers only need to input measured parameters to quickly complete risk assessment and prevention and control strategy formulation. In addition, this invention fully considers the special corrosion behavior characteristics of water-oil stratification and local pitting aggravation caused by long-term static immersion of the medium under intermittent operation conditions. It automatically applies the corresponding evaluation rules when the medium is static and the flow rate is zero, making it specifically applicable to the actual engineering needs of intermittently operating pipelines such as national strategic oil reserve depots. In contrast, related technologies use slug flow as a correction factor and implicitly assume continuous flow conditions, making their evaluation framework inherently unsuitable for intermittently operating pipelines.

[0043] Finally, the embodiments of the present invention will be explained and described in conjunction with the accompanying drawings: like Figure 3 The diagram shown is a system architecture framework diagram in an embodiment of the present invention. The diagram displays the complete signal flow and data flow from the data acquisition layer (wall thickness detection, corrosion rate, and seven environmental parameters) through the dual-dimensional evaluation layer (wall thickness reduction safety evaluation and comprehensive corrosion risk evaluation) to the collaborative decision-making layer (dual-dimensional decision matrix and four-level differentiated prevention and control) in a hierarchical structure.

[0044] like Figure 4 The figure shown is a threshold division diagram for the wall thickness reduction safety level in an embodiment of the present invention. The figure uses stacked bar charts to show the threshold boundary division of the Tmm / T0 ratio in four safety level intervals (Level I: Continued use >0.9, Level II: Enhanced monitoring 0.5~0.9, Level III: Planned maintenance 0.2~0.5, Level IV: Immediate maintenance ≤0.2).

[0045] like Figure 5 The figure shown is a basic risk level threshold diagram of corrosion rate in an embodiment of the present invention. The diagram uses a bar chart to show the four levels of corrosion rate thresholds (Level I <0.025mm / a, Level II 0.025~0.12mm / a, Level III 0.12~0.25mm / a, Level IV ≥0.25mm / a) determined by the NACE SP0775 standard combined with intermittent operating condition measured data. Each level is distinguished by a different color.

[0046] like Figure 6 The diagram shown is a two-dimensional collaborative decision-making matrix diagram in an embodiment of the present invention. The diagram displays the four-level prevention and control strategy in the form of a heat map, which intersects the wall thickness reduction safety level (vertical axis) and the comprehensive corrosion risk level (horizontal axis). The colors range from green (routine monitoring) to red (immediate repair plus continuous corrosion inhibition adjustment). Each cell is labeled with specific prevention and control measures.

[0047] Reference Figure 2 A corrosion safety assessment and classification prevention system for oil pipelines, comprising: The first module 201 is used to collect wall thickness detection data, corrosion rate data and several environmental and operating parameters at various measuring points of the pipeline. The second module 202 is used to process the wall thickness detection data to determine the safety level of wall thickness reduction and obtain the first dimension evaluation result. The third module 203 is used to perform a comprehensive corrosion risk correction assessment based on corrosion rate data and several environmental and operational parameters to obtain the second dimension evaluation results. The fourth module 204 is used for two-dimensional collaborative decision-making based on the evaluation results of the first dimension and the evaluation results of the second dimension to obtain the pipeline corrosion safety classification and prevention strategy.

[0048] The content of the above method embodiments is applicable to this system embodiment. The specific functions implemented in this system embodiment are the same as those in the above method embodiments, and the beneficial effects achieved are also the same as those achieved in the above method embodiments.

[0049] The preferred embodiments of the present application have been described above with reference to the accompanying drawings, but this is not intended to limit the scope of the embodiments of the present application. Any modifications, equivalent substitutions, and improvements made by those skilled in the art without departing from the scope and substance of the embodiments of the present application shall be within the scope of the embodiments of the present application.

Claims

1. A method for safety assessment and graded prevention of corrosion in oil pipelines, characterized in that, Includes the following steps: Collect wall thickness detection data, corrosion rate data, and several environmental and operational parameters at various measuring points along the pipeline. The wall thickness detection data is processed to determine the safety level of wall thickness reduction, and the first dimension evaluation result is obtained. Based on corrosion rate data and several environmental and operational parameters, a comprehensive corrosion risk correction assessment was performed to obtain the second-dimensional evaluation results. Based on the evaluation results of the first and second dimensions, a two-dimensional collaborative decision-making process is performed to obtain a safety classification and prevention strategy for pipeline corrosion.

2. The method for safety assessment and graded prevention of corrosion in oil pipelines according to claim 1, characterized in that, The wall thickness detection data specifically includes the minimum remaining wall thickness and the original wall thickness, and the environmental and operating parameters specifically include chloride ion concentration, sulfur ion concentration, water-oil ratio, medium flow rate, temperature, carbon dioxide partial pressure, and elbow geometry.

3. The method for safety assessment and graded prevention of corrosion in oil pipelines according to claim 2, characterized in that, The first dimension evaluation result includes a first-level wall thickness reduction safety level, a second-level wall thickness reduction safety level, a third-level wall thickness reduction safety level, and a fourth-level wall thickness reduction safety level. The step of processing the wall thickness detection data to determine the wall thickness reduction safety level and obtaining the first dimension evaluation result specifically includes: Obtain the ratio of the minimum remaining wall thickness to the original wall thickness, and determine the wall thickness ratio. If the wall thickness ratio is greater than the first preset wall thickness ratio threshold, it is determined to be the first level of wall thickness reduction safety level; If the wall thickness ratio is greater than the second preset wall thickness ratio threshold and less than or equal to the first preset wall thickness ratio threshold, it is determined to be the second level of wall thickness reduction safety level. If the wall thickness ratio is greater than the third preset wall thickness ratio threshold and less than or equal to the second preset wall thickness ratio threshold, it is determined to be the third level of wall thickness reduction safety level. If the wall thickness ratio is not greater than the third preset wall thickness ratio threshold or the minimum remaining wall thickness is not greater than the preset minimum wall thickness threshold, it is determined to be the fourth level of wall thickness reduction safety level.

4. The method for corrosion safety assessment and graded prevention and control in oil pipelines according to claim 3, characterized in that, The step of performing a comprehensive corrosion risk correction assessment based on corrosion rate data combined with several environmental and operational parameters to obtain the second-dimensional evaluation result specifically includes: The corrosion rate data is processed to determine the basic risk level, thus obtaining the basic risk level. Several environmental and operational parameters are individually corrected and scored to obtain a cumulative correction score. The basic risk level is adjusted based on the cumulative correction score to obtain the final comprehensive corrosion risk level, and the second dimension evaluation result is output.

5. The method for corrosion safety assessment and graded prevention and control in oil pipelines according to claim 4, characterized in that, The basic risk levels include a first-level basic risk level, a second-level basic risk level, a third-level basic risk level, and a fourth-level basic risk level. The step of determining the basic risk level by processing the corrosion rate data specifically includes: If the corrosion rate data is less than the first preset corrosion rate threshold, it is determined to be the first level of basic risk. If the corrosion rate data is greater than or equal to the first preset corrosion rate threshold and less than the second preset corrosion rate threshold, it is determined to be the second level of basic risk. If the corrosion rate data is greater than or equal to the second preset corrosion rate threshold and less than the third preset corrosion rate threshold, it is determined to be a level three basic risk level. If the corrosion rate data is greater than or equal to the third preset corrosion rate threshold, it is determined to be a level four basic risk level.

6. The method for safety assessment and graded prevention of corrosion in oil pipelines according to claim 5, characterized in that, The step of performing itemized correction scoring on several environmental and operational parameters to obtain a cumulative correction score specifically includes: For each environmental and operational parameter, the measured value is matched with the corresponding preset multi-level parameter threshold to obtain the single correction score for each parameter. The cumulative correction score is obtained by summing up all individual correction scores.

7. The method for corrosion safety assessment and graded prevention and control in oil pipelines according to claim 6, characterized in that, The step of adjusting the basic risk level based on the cumulative correction score to obtain the final comprehensive corrosion risk level specifically includes: If the cumulative correction score is greater than or equal to the first preset score threshold, the current basic risk level will be raised by two levels. If the cumulative correction score is greater than or equal to the second preset score threshold and less than the first preset score threshold, the current basic risk level will be raised by one level. If the cumulative corrected score is less than the second preset score threshold, the current basic risk level will remain unchanged. If the current basic risk level is already at Level 4, it will not be upgraded further.

8. The method for safety assessment and graded prevention of corrosion in oil pipelines according to claim 7, characterized in that, The step of performing dual-dimensional collaborative decision-making based on the first-dimensional evaluation results and the second-dimensional evaluation results to obtain the pipeline corrosion safety classification and prevention strategy specifically includes: If the current wall thickness reduction safety level reaches the preset structural intervention level, the structural intervention strategy will be output first, and the current comprehensive corrosion risk level will be used as an auxiliary basis for corrosion cause analysis and operation plan optimization. If the current wall thickness reduction safety level does not reach the preset structural intervention level, output corrosion monitoring and control measures of corresponding intensity based on the current comprehensive corrosion risk level.

9. The method for safety assessment and graded prevention of corrosion in oil pipelines according to claim 8, characterized in that, The step of outputting corrosion monitoring and control measures of corresponding intensity based on the current comprehensive corrosion risk level specifically includes: If the risk level is Level 1, routine monitoring will be conducted and a corrosion trend report will be submitted according to the first preset cycle. If it is the second level of basic risk, then intensified monitoring will be carried out, and the corrosion rate and thinning thickness will be evaluated according to the second preset cycle. If the risk level is Level 3, enhanced monitoring will be implemented, and the corrosion rate and thinning thickness will be evaluated according to the third preset cycle. Online corrosion monitoring will be added and the corrosion inhibitor injection scheme will be optimized. If the risk level is Level 4, continuous monitoring will be conducted to track the corrosion rate and thinning thickness in real time. The corrosion inhibitor strategy will be adjusted immediately, and corrosion trend analysis will be submitted according to the fourth preset cycle.

10. A corrosion safety assessment and classification prevention system for oil pipelines, characterized in that, Includes the following modules: The first module is used to collect wall thickness detection data, corrosion rate data, and several environmental and operational parameters at various measuring points in the pipeline. The second module is used to process the wall thickness detection data to determine the safety level of wall thickness reduction, and obtain the first dimension evaluation result. The third module is used to perform a comprehensive corrosion risk correction assessment based on corrosion rate data and several environmental and operational parameters to obtain the second-dimensional evaluation results. The fourth module is used for two-dimensional collaborative decision-making based on the evaluation results of the first and second dimensions to obtain a pipeline corrosion safety classification and prevention strategy.

Images