A method and device for online nondestructive time-space resolution monitoring of corrosion in pipelines

Abstract

The present invention discloses an online non-destructive time-space resolution monitoring device for corrosion in pipelines, the monitoring device at least comprises a fixture, an electrochemical sensor and an electrochemical workstation, the electrochemical sensor is electrically connected to the electrochemical workstation, and the electrochemical sensor is fixed on the outer wall of the pipeline to be tested through the fixture. The device uses an external electrochemical workstation to detect the in-situ electrochemical signal of metal material corrosion, and carries out tests on the potential distribution diagram, current distribution diagram and space charge layer thickness distribution diagram of different regions at different times, so as to realize time-space resolution monitoring of corrosion in pipelines.

Description

Technical Field

[0001] The present invention belongs to the field of oil and gas field corrosion and protection, and in particular relates to a method and device for monitoring corrosion in a pipeline in a high-temperature, high-pressure and high-hydrogen sulfide environment with time and space resolution. Background Art

[0002] With the development of oil and gas fields, the corrosion environment is becoming more and more harsh, and more oil and gas pipes are in high temperature, high pressure, and high H2S environments. When carbon steel or low alloy steel is exposed to high temperature, high pressure, and high H2S environmental media, in addition to the formation of FeS film on the surface, hydrogen generated by corrosion intrudes into the steel, causing hydrogen induced cracking. Hydrogen bubbles can be seen on the surface of the steel, and sulfide stress corrosion cracking will also occur under stress.

[0003] Nowadays, electrochemical testing methods are widely used at home and abroad to study the corrosion laws of H2S environments. However, the three-electrode system electrochemical testing devices commonly used at home and abroad currently use one-piece alloy or glass containers. For example, China Invention Authorization Publication No.: CN104568726A discloses a high-temperature and high-pressure corrosion hydrogen permeation kinetics test device and test method. The invention provides a fracture form of a material under the coupling of corrosion hydrogen permeation and fatigue load under high temperature and high pressure, and can test the fatigue load of the material in a short time. The disadvantage of this patent is that it cannot achieve online monitoring in space and time under high temperature and high pressure. China Invention Authorization Publication No.: CN105699285A discloses an electrochemical device for corrosion testing under elemental sulfur scale. The invention improves the traditional one-piece alloy electrochemical testing device, sets the working electrode jack on the lower cover, and the working electrode passes through the working electrode jack from bottom to top, which is convenient for fixing the scale sample on the working electrode. The defect of this patent is the state of the sample after corrosion under elemental sulfur scale, and the corrosion process of the sample cannot be monitored in real time.

[0004] The online corrosion monitoring methods for oil and gas pipelines in the petroleum industry mainly include electrochemical AC impedance probes, resistance probes, and inductance probes. When in use, they all have certain limitations and are applicable to normal temperature and pressure. However, in actual industrial corrosion monitoring, there are disadvantages in pipeline corrosion monitoring in high temperature and high pressure environments. For example: electrochemical AC impedance probes, due to the wide frequency range of AC impedance testing and the long time required during the test, it is difficult to reflect the real-time corrosion status; resistance probes are greatly affected by interference factors such as temperature; the corrosion monitoring results of inductance probes are also affected by temperature, mainly due to the influence of temperature on the magnetic conductivity of steel materials; none of them can realize the monitoring of pipeline inner wall corrosion in time and space.

[0005] It is for this reason that the petrochemical, metal processing and smelting industries tend to use non-destructive monitoring methods to avoid possible risks when conducting online corrosion monitoring. Therefore, what means and devices should be used to achieve temporal and spatial corrosion monitoring of high-temperature, high-pressure and high-H2S pipelines is an urgent problem to be solved. Summary of the invention

[0006] The purpose of the present invention is to provide an online non-destructive time-space resolution monitoring device for pipeline corrosion in order to overcome the defects of the prior art. The device uses an external electrochemical workstation to detect the in-situ electrochemical signals of metal material corrosion, and carries out potential distribution diagrams, current distribution diagrams and space charge layer thickness distribution diagram tests in different areas at different times, so as to realize time-space resolution monitoring of pipeline corrosion.

[0007] The object of the present invention is achieved through the following technical solutions:

[0008] An online nondestructive time-space resolution monitoring device for corrosion in a pipeline, the monitoring device at least comprises a clamp, an electrochemical sensor and an electrochemical workstation, the electrochemical sensor is electrically connected to the electrochemical workstation, and the electrochemical sensor is fixed on the outer wall of the pipeline to be tested through the clamp; the electrochemical sensor at least comprises: a three-electrode lead, a capillary reference electrode, a capillary auxiliary electrode, a microtube and a copper rod, one end of the copper rod is connected to the pipeline as a working electrode, and a plurality of microtubes are arranged in the copper rod, the capillary reference electrode and the capillary auxiliary electrode are arranged in the microtube, and the microtube is filled with electrolyte, and the electrolyte contacts the outer wall of the pipeline to be tested; one end of the three-electrode lead is respectively connected to the capillary reference electrode, the capillary auxiliary electrode and the copper rod, and the other end is connected to the electrochemical workstation.

[0009] According to a preferred embodiment, the monitoring device further comprises a computing and processing unit, which is configured to complete the recording, analysis, processing and output of electrochemical signal data of the capillary reference electrode, the capillary auxiliary electrode and the working electrode.

[0010] According to a preferred embodiment, the connecting end of the copper rod and the pipe is provided with a groove structure matching the outer wall of the pipe.

[0011] According to a preferred embodiment, the axis of the microtube is arranged parallel to the axis of the copper rod; and the capillary reference electrode and the capillary auxiliary electrode are arranged along the axis direction of the microtube.

[0012] According to a preferred embodiment, an electrochemical sensor housing is provided on the outer side of the side wall of the copper rod, and an electrochemical sensor front cover is provided at the end of the copper rod.

[0013] According to a preferred embodiment, the electrochemical sensor housing is a Hastelloy housing; and an insulating filling material is provided between the electrochemical sensor housing and the copper rod.

[0014] According to a preferred embodiment, the three-electrode lead passes through the central hole on the front cover of the electrochemical sensor and is connected to the electrochemical workstation.

[0015] According to a preferred embodiment, the clamp is made of insulating material.

[0016] An online nondestructive time-space resolution monitoring method for pipeline internal corrosion, the method comprising the following steps: step 1: grinding and cleaning the outer wall of the pipeline to be tested; step 2: using a clamp to closely contact the electrochemical sensor with the outer wall of the pipeline; step 3: connecting the three-electrode leads in the electrochemical sensor to an external electrochemical workstation, receiving a signal, and starting an experimental test; step 4: connecting an external computing processing unit to the external electrochemical workstation to record, analyze, process and output data collected by the electrochemical workstation; step 5: designing experimental corrosion media, temperature and pressure conditions according to the required simulated field working conditions, starting an in-situ electrochemical test, thereby obtaining potential distribution diagrams, current distribution diagrams and space charge layer thickness distribution diagrams in different regions at different times, and realizing time-space resolution monitoring of pipeline internal corrosion.

[0017] The aforementioned main scheme of the present invention and its further options can be freely combined to form multiple schemes, all of which are schemes that can be adopted and claimed for protection by the present invention; and in the present invention, (non-conflicting options) options and other options can also be freely combined. After understanding the scheme of the present invention, those skilled in the art can understand that there are many combinations based on the prior art and common knowledge, all of which are technical schemes to be protected by the present invention, and they are not exhaustively listed here.

[0018] Beneficial effects of the present invention: The in-situ electrochemical signals of metal material corrosion are detected by the device and method of the present invention, and the potential distribution diagram, current distribution diagram and space charge layer thickness distribution diagram tests in different areas at different times are carried out, thereby realizing the time-space resolution monitoring of corrosion in the pipeline. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of the on-line nondestructive time-space resolution monitoring device for pipeline internal corrosion of the present invention;

[0020] Figure 2 It is a schematic diagram of the structure of the electrochemical sensor in the on-line nondestructive time-space resolution monitoring device for pipeline internal corrosion of the present invention;

[0021] Figure 3It is a schematic diagram of the cross-sectional structure of the electrochemical sensor in the on-line nondestructive time-space resolution monitoring device for pipeline internal corrosion of the present invention;

[0022] Figure 4 It is a schematic diagram of the fixture structure in the on-line nondestructive time-space resolution monitoring device for pipeline internal corrosion of the present invention.

[0023] Among them, 1-three-electrode lead, 2-electrochemical sensor front cover, 3-capillary reference electrode, 4-capillary auxiliary electrode, 5-microtube, 6-copper rod, 7-electrochemical sensor housing, 8-clamp, 9-pipeline, 10-bolt, 11-nut. DETAILED DESCRIPTION

[0024] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0025] It should be noted that in order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments.

[0026] Therefore, the following detailed description of the embodiments of the present invention is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of 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.

[0027] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate the orientation or position relationship that the product of the invention is usually placed in when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0028] In addition, the terms "horizontal", "vertical", "overhanging" and the like do not mean that the components are required to be absolutely horizontal or overhanging, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0029] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0030] In addition, the present invention should be pointed out that, in the present invention, unless the specific structure, connection relationship, positional relationship, power source relationship, etc. are specifically written out, the structure, connection relationship, positional relationship, power source relationship, etc. involved in the present invention are all known by those skilled in the art on the basis of the prior art without creative work.

[0031] Embodiment 1:

[0032] refer to Figures 1 to 4 As shown, the present invention discloses an on-line non-destructive time-space resolution monitoring device for pipeline internal corrosion.

[0033] Preferably, the monitoring device at least comprises a clamp 8, an electrochemical sensor and an electrochemical workstation. The electrochemical sensor is electrically connected to the electrochemical workstation, and the electrochemical sensor is fixed on the outer wall of the pipeline 9 to be tested via the clamp 8.

[0034] Preferably, the clamp 8 is a clamp-type structure. The clamp 8 is fastened with bolts 9 and nuts 10. The electrochemical sensor is tightly combined with the pipe 9 to be tested via the clamp 8. Furthermore, the clamp 8 is made of insulating material.

[0035] An external electrochemical workstation is used to detect the in-situ electrochemical signals of metal material corrosion, and tests of potential distribution, current distribution and space charge layer thickness distribution in different areas at different times are carried out to achieve time-space resolution monitoring of corrosion in pipelines.

[0036] Preferably, the monitoring device further comprises a computing unit configured to complete the recording, analysis, processing and output of electrochemical signal data of the capillary reference electrode 3, the capillary auxiliary electrode 4 and the working electrode. The computing unit includes but is not limited to a computer.

[0037] Preferably, the electrochemical sensor at least comprises: a three-electrode lead 1 , a capillary reference electrode 3 , a capillary auxiliary electrode 4 , a microtube 5 and a copper rod 6 .

[0038] Preferably, one end of the copper rod 6 is connected to a pipe 9 as a working electrode, and a plurality of microtubes 5 are arranged in the copper rod 6. A groove structure matching the outer wall of the pipe 9 is arranged at the connecting end of the copper rod 6 and the pipe 9.

[0039] Preferably, the capillary reference electrode 3 and the capillary auxiliary electrode 4 are disposed in the microtube 5 , and the microtube 5 is filled with an electrolyte that contacts the outer wall of the pipe 9 .

[0040] Preferably, the axis of the microtube 5 is arranged parallel to the axis of the copper rod 6 ; and the capillary reference electrode 3 and the capillary auxiliary electrode 4 are arranged along the axis direction of the microtube 5 .

[0041] Furthermore, the electrochemical sensor microtube 5 and the test pipe 9 are connected with a sealing gasket, which can tightly fit the electrolyte inside the tube body with the pipe 9 to be tested. The working electrode area is the area where the electrolyte contacts the outer wall of the pipe 9.

[0042] Preferably, one end of the three-electrode lead 1 is connected to the capillary reference electrode 3, the capillary auxiliary electrode 4 and the copper rod 6 respectively, and the other end is connected to the electrochemical workstation.

[0043] Preferably, an electrochemical sensor housing 7 is provided on the outer side of the side wall of the copper rod 6 , and an electrochemical sensor front cover 2 is provided at the end direction of the copper rod 6 .

[0044] Furthermore, the electrochemical sensor housing 7 is a Hastelloy housing. An insulating filling material is provided between the electrochemical sensor housing 7 and the copper rod 6 .

[0045] Preferably, the three-electrode lead 1 passes through the central hole on the electrochemical sensor front cover 2 and is connected to the electrochemical workstation.

[0046] Example 2

[0047] Based on Example 1, the present invention also discloses an online non-destructive time-space resolution monitoring method for corrosion in pipelines.

[0048] The method comprises the following steps:

[0049] Step 1: Pre-grinding and cleaning of the outer wall of the pipe 9 to be tested;

[0050] Step 2: Use a clamp 8 to bring the electrochemical sensor into close contact with the outer wall of the pipe 9;

[0051] Step 3: Connect the three-electrode lead 1 in the electrochemical sensor to the external electrochemical workstation, receive the signal, and start the experimental test;

[0052] Step 4: Connect the computing processing unit of the peripheral device to the external electrochemical workstation to record, analyze, process and output the data collected by the electrochemical workstation;

[0053] Step 5: According to the required simulated on-site working conditions, the experimental corrosion medium, temperature, and pressure conditions are designed, and the in-situ electrochemical test is started to obtain the potential distribution diagram, current distribution diagram, and space charge layer thickness distribution diagram of different regions at different times, so as to realize the time-space resolution monitoring of the corrosion in the pipeline 9.

[0054] The test pipeline 9 under simulated working conditions will have a thicker rust layer on its outer wall and interior due to long-term storage, and the metal layer generally has larger "voids" and pits of varying depths generated during the metal processing process, and there are oil stains on the surface of the metal pipeline. When the pipeline is used for corrosion monitoring, the effect requirements on the tested parts are high, and improvements must be made in terms of degreasing, pickling and passivation of the pipeline. If only the same pretreatment method as the working electrode used in the corrosion experiment under experimental conditions is used, the next step of work will be impossible to carry out to a large extent.

[0055] The preferred implementation of the present invention is described in detail above in conjunction with the accompanying drawings, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be modified in a variety of simple ways, for example, testing the Mott-Schottky curve to study the semiconductor characteristics of the passivation film on the surface of the metal pipe.

[0056] The present invention realizes online nondestructive monitoring of pipeline corrosion in a high-temperature, high-pressure, and high-H2S environment, can obtain the changes in potential, current, and space charge layer thickness in time and space, and grasp the corrosion behavior and mechanism research in the pipeline in the high-temperature, high-pressure, and high-H2S environment, and the operation is convenient and effective.

[0057] The above basic examples of the present invention and their further selected examples can be freely combined to form multiple embodiments, all of which are embodiments that can be adopted and claimed by the present invention. In the scheme of the present invention, each selected example can be arbitrarily combined with any other basic example and selected example. Those skilled in the art will know that there are many combinations.

Claims

1. An online non-destructive time-space resolution monitoring device for pipeline internal corrosion, characterized in that: The monitoring device comprises at least a clamp (8), an electrochemical sensor and an electrochemical workstation, the electrochemical sensor being electrically connected to the electrochemical workstation, and the electrochemical sensor being fixed to the outer wall of the pipeline to be tested (9) via the clamp; The electrochemical sensor comprises at least: a three-electrode lead (1), a capillary reference electrode (3), a capillary auxiliary electrode (4), a microtube (5) and a copper rod (6). One end of the copper rod (6) is connected to a pipe (9) serving as a working electrode, and a plurality of microtubes (5) are arranged inside the copper rod (6), the capillary reference electrode (3) and the capillary auxiliary electrode (4) are arranged inside the microtubes (5), and the microtubes (5) are filled with electrolytes, and the electrolytes are in contact with the outer wall of the pipe (9) to be tested; One end of the three-electrode lead (1) is respectively connected to the capillary reference electrode (3), the capillary auxiliary electrode (4) and the copper rod (6), and the other end is connected to the electrochemical workstation; The monitoring device further comprises a computing and processing unit, wherein the computing and processing unit is configured to complete the recording, analysis, processing and output of electrochemical signal data of the capillary reference electrode (3), the capillary auxiliary electrode (4) and the working electrode; The connecting end of the copper rod (6) and the pipe (9) is provided with a groove structure matching the outer wall of the pipe (9); The axis of the microtube (5) is arranged parallel to the axis of the copper rod (6); Furthermore, the capillary reference electrode (3) and the capillary auxiliary electrode (4) are arranged along the axial direction of the microtube (5).

2. The on-line nondestructive time-space resolution monitoring device for pipeline internal corrosion according to claim 1, characterized in that: An electrochemical sensor housing (7) is provided on the outer side of the side wall of the copper rod (6), and an electrochemical sensor front cover (2) is provided in the end direction of the copper rod (6).

3. The on-line nondestructive time-space resolution monitoring device for pipeline internal corrosion according to claim 2, characterized in that: The electrochemical sensor housing (7) is a Hastelloy housing; An insulating filling material is provided between the electrochemical sensor housing (7) and the copper rod (6).

4. The on-line nondestructive time-space resolution monitoring device for pipeline internal corrosion according to claim 2, characterized in that: The three-electrode lead (1) passes through the central hole on the electrochemical sensor front cover (2) and is connected to the electrochemical workstation.

5. The on-line nondestructive time-space resolution monitoring device for pipeline internal corrosion according to claim 1, characterized in that: The clamp (8) is made of insulating material.

6. An online non-destructive time-space resolution monitoring method for pipeline internal corrosion, characterized in that: Using the monitoring device as claimed in claim 1, the method comprises the following steps: Step 1: grinding and cleaning the outer wall of the pipe to be tested (9); Step 2: Using a clamp (8) to bring the electrochemical sensor into close contact with the outer wall of the pipe (9); Step 3: Connect the three-electrode leads in the electrochemical sensor to the external electrochemical workstation, receive the signal, and start the experimental test; Step 4: Connect the computing processing unit of the peripheral device to the external electrochemical workstation to record, analyze, process and output the data collected by the electrochemical workstation; Step 5: Design the experimental corrosion medium, temperature, and pressure conditions according to the required simulated field working conditions, and start the in-situ electrochemical test to obtain the potential distribution diagram, current distribution diagram, and space charge layer thickness distribution diagram of different regions at different times, so as to realize the time-space resolution monitoring of the corrosion in the pipeline (9).

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