Quantitative evaluation device and method for gas migration process in seabed

Abstract

The invention provides a quantitative evaluation device and method for a gas migration process in a seabed, the quantitative evaluation device comprises a penetration conical tip section and a data acquisition section, and methane sensor sections are sequentially arranged between the penetration conical tip section and the data acquisition section. The problems that an existing underwater methane sensor is difficult to measure the methane concentration in the seabed, equipment is redundant, and long-term monitoring is inconvenient are solved, the method capable of monitoring the methane concentration of sediments at different depths at the same time is provided, and monitoring of space-time change of the methane concentration is achieved. According to the equipment, a plurality of underwater methane sensors are combined with a deep sea feeler lever, a seabed methane sensor array in the seabed shallow gas migration process is designed, the feeler lever provided with the methane sensors goes deep into a sediment layer through the dead weight (capable of being assembled) of the equipment, sediment seawater enters and exits through permeable stones, and the sensors complete calculation of methane concentration. Therefore, the purpose of monitoring the methane concentration in the sediment is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of seabed environment observation and marine engineering geology, and in particular to a device and method for quantitatively evaluating a gas migration process in a seabed. Background Art

[0002] Submarine shallow gas usually refers to the gas accumulated in sediments within 1000m below the seabed. It is distributed in the East China Sea, South China Sea and Yellow Sea and Bohai Sea in China. The escape of shallow gas can lead to geological disasters such as landslides and pits. When the escape is serious, it can lead to the rupture of oil and gas pipelines, the instability of pile foundations and other facilities, which has caused great obstacles to engineering exploration and construction. Therefore, studying the migration mechanism of shallow gas is of great significance to ensure the safety of marine engineering and national energy security, and monitoring the gas concentration in submarine sediments is essential for studying the migration mechanism of submarine gas. Current studies have shown that the main component of seabed seepage gas is methane. When methane migrates in the seabed, how to monitor the methane concentration in sediments for a long time and the temporal and spatial changes of methane concentration at different depths of the seabed is a difficult problem. Existing underwater methane sensors are only suitable for measuring methane concentration in water, but there is a lack of research methods for entering the seabed to monitor the methane concentration in sediments at multiple depths and long-term in-situ monitoring. Therefore, high-precision, pressure-resistant and long-term monitoring seabed methane sensors are needed to conduct multi-depth joint monitoring of methane concentrations inside the seabed. Summary of the invention

[0003] In order to make up for the shortcomings of the prior art, the present invention provides a quantitative evaluation device and method for the gas migration process in the seabed, which solves the problems of the current underwater methane sensor that it is difficult to measure the methane concentration in the seabed, the equipment is complicated, and the long-term monitoring is inconvenient, and provides a method that can simultaneously monitor the gas concentration of sediments at different depths, realizing the monitoring of the temporal and spatial changes of gas concentration. This patent plans to combine multiple underwater methane sensors with deep-sea probes, design a seabed methane sensor array for the migration process of shallow seabed gas, and use the weight of the equipment to penetrate the probe equipped with methane sensors into the shallow gas-rich sediment layer, and complete the entry and exit of sediment seawater through permeable stones, thereby achieving the purpose of monitoring the gas concentration in the sediment and evaluating the migration rate of gas in the seabed.

[0004] The present invention is realized by the following technical scheme: a quantitative evaluation device for gas migration process in the seabed, wherein the seabed methane concentration monitoring probe for the seabed during the migration process of shallow seabed gas comprises a penetration cone tip section and a data acquisition section, wherein a methane sensor section is sequentially arranged between the penetration cone tip section and the data acquisition section, the methane sensor section comprises a first underwater methane sensor section, a second underwater methane sensor section and a third underwater methane sensor section, and a connecting section is arranged between the penetration cone tip section, the first underwater methane sensor section, the second underwater methane sensor section, the third underwater methane sensor section and the data acquisition section, and each section is connected by a thread; The first underwater methane sensor segment, the second underwater methane sensor segment and the third underwater methane sensor segment have the same structure. Both ends of the first underwater methane sensor segment are provided with a first internal thread. A permeable stone is provided on the left side of the first underwater methane sensor segment and a small hole is provided on the permeable stone. A sealing groove is provided on the right side of the permeable stone. A rubber strip for waterproofing is installed on the sealing groove. A steel plate is fixedly welded inside the first underwater methane sensor segment, and a methane sensor is fixedly installed on the steel plate by bolts. The permeable stone and the first underwater methane sensor segment are directly connected to two seawater channel pipes to realize the input and output of seawater. The seawater channel pipe passes through the sealing groove to transport seawater to the methane sensor. The measured methane concentration data is transmitted to the data acquisition segment through a watertight cable at the top of the methane sensor. A porous metal plate is fixedly installed on the inner cavity of the methane sensor. The porous metal plate divides the inner cavity of the methane sensor into two parts, the left part is a seawater storage chamber, and the right part is a sensor cavity. The seawater storage chamber is located at the tail of the inner cavity of the methane sensor. A silicone rubber semipermeable membrane is arranged on the right side of the seawater storage chamber. The silicone rubber semipermeable membrane is fixedly installed on the porous metal plate. A semiconductor methane sensor probe is arranged in the sensor cavity. The outer surface of the data acquisition section is a pressure cabin shell. A hatch cover is installed at the right end of the data acquisition section. A second internal thread is provided at the left end of the data acquisition section and is connected to the connecting section. A DC power supply group, a data collector, a data acquisition control module and a compensating oil tank are installed inside the data acquisition section. A watertight cable is connected to the data collector. The data collector is equipped with an SD card. A watertight connector is fixedly installed on the hatch cover and electrically connected to the DC power supply group, the data collector and the data acquisition control module. The data acquisition control module can set a self-contained acquisition mode, that is, connect the probe rod to the PC end, and pre-set the acquisition parameters of each methane sensor including sleep time, acquisition time and acquisition frequency through the upper computer software. Then the probe rod is disconnected from the PC end and deployed inside the seabed for work. The collected data is stored in the SD card, and the battery capacity can provide self-contained continuous acquisition for 3 months.

[0005] As a preferred solution, the first internal thread and the second internal thread are respectively provided with a first sealing groove and a second sealing groove.

[0006] As a preferred option, the hatch cover has a sealing groove to ensure the dryness of the cabin, and the material can withstand pressure at a water depth of up to 2,000 meters.

[0007] A method for quantitatively evaluating a gas migration process in a seabed, comprising the following steps: S1: The data acquisition control module can be set to self-contained acquisition mode; S2: Insert the seabed gas concentration monitoring probe into the seabed; S3: The seawater containing dissolved methane slowly penetrates into the methane sensor section through the permeable stone. The inflowing seawater enters the seawater storage chamber at the tail of the methane sensor. The dissolved gas in the seawater can penetrate into the sensor cavity through the silicone rubber semipermeable membrane supported by the porous metal plate and gradually diffuse in the cavity. There are gas phase and liquid phase gas on the inner and outer sides of the silicone rubber semipermeable membrane respectively. According to Henry's law, in a sealed container at a certain temperature, the molar concentration of the gas in the solution is proportional to the partial pressure of the gas. When the gas partial pressure on one side is too large, the gas on that side will penetrate through the semipermeable membrane to the other side until the gas partial pressure on both sides of the semipermeable membrane reaches equilibrium. The conductivity change produced by the reaction of the oxide semiconductor gas-sensitive material with methane gas is as shown in equation (1). (1) The semiconductor methane sensor probe (275) installed in the sensor cavity outputs a voltage signal, and based on the correction of formulas (2) and (3), the changing voltage signal is converted into an actual methane concentration value, thereby realizing the monitoring of the change of methane concentration over time. The calculation formulas are as follows: (2) (3) in, c is the methane concentration, ; t is the gas temperature, °C; V CH4 is the methane output voltage; V t is the temperature output voltage, V; k 1 - k 9 is a constant obtained through experimental statistical induction.

[0008] As a preferred solution, the self-contained acquisition mode in step S1 has the following specific steps: connecting the probe rod to the PC, pre-setting the acquisition parameters of each methane sensor including sleep time, acquisition time, and acquisition frequency through the host computer software, and then disconnecting the probe rod from the PC and deploying it inside the seabed to work. The acquired data is stored in the SD card.

[0009] Due to the adoption of the above technical solution, the present invention has the following beneficial effects compared with the prior art: it solves the problems of the current underwater methane sensor being difficult to measure the methane concentration in the seabed, the complicated equipment, and the inconvenience of long-term monitoring, and provides a method that can simultaneously monitor the methane concentration of sediments at different depths, thereby realizing the monitoring of the spatiotemporal changes of the methane concentration. The device combines multiple underwater methane sensors with deep-sea probes, designs a seabed methane sensor array for the migration process of shallow seabed gas, and uses the device's own weight to penetrate the probe equipped with the methane sensor into the sediment layer, and completes the entry and exit of the sediment seawater through the permeable stone. The sensor completes the calculation of the methane concentration, thereby achieving the purpose of monitoring the methane concentration in sediments at different depths, and can also complete the monitoring of the temporal and spatial changes of the methane concentration.

[0010] Additional aspects and advantages of the present invention will become apparent from the following description or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which: Figure 1 It is a structural schematic diagram of the present invention; Figure 2 It is a structural schematic diagram of the methane sensor section; Figure 3 It is a structural schematic diagram of a methane sensor; Figure 4 It is a structural diagram of the data acquisition section; in, Figures 1 to 4 The corresponding relationship between the reference numerals and the components is as follows: 1 cone tip section, 2 methane sensor section, 3 data acquisition section, 201 first underwater methane sensor section, 202 second underwater methane sensor section, 203 third underwater methane sensor section, 21 first sealing groove, 22 permeable stone, 23 sealing groove, 24 seawater channel pipe, 25 steel plate, 26 bolt, 27 methane sensor, 271 seawater storage chamber, 272 porous metal plate, 273 silicone rubber semipermeable membrane, 274 sensor cavity, 275 semiconductor methane sensor probe, 28 watertight cable, 29 first internal thread, 31 second sealing groove, 32 second internal thread, 3312V DC power supply group, 34 data acquisition unit, 35 data acquisition control module, 36 compensation oil tank configured in the cabin, 37 hatch cover, 38 watertight connector. DETAILED DESCRIPTION

[0012] In order to more clearly understand the above-mentioned purpose, features and advantages of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

[0013] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited to the specific embodiments disclosed below.

[0014] Combine the following Figures 1 to 4 The device and method for quantitatively evaluating the gas migration process in the seabed according to the embodiment of the present invention are described in detail.

[0015] like Figure 1 As shown, the present invention proposes a device and method for quantitatively evaluating the gas migration process in the seabed. The methane concentration monitoring probe in the seabed during the seabed shallow gas migration process includes a penetration cone tip section 1 and a data acquisition section 3, wherein, as Figure 1 As shown, a methane sensor segment 2 is sequentially arranged between the penetration cone tip segment 1 and the data acquisition segment 3, and the methane sensor segment 2 includes a first underwater methane sensor segment 201, a second underwater methane sensor segment 202 and a third underwater methane sensor segment 203. A connecting segment 4 is arranged between the penetration cone tip segment 1, the first underwater methane sensor segment 201, the second underwater methane sensor segment 202, the third underwater methane sensor segment 203 and the data acquisition segment 3, and each segment is connected by a thread; the penetration cone tip segment 1 is a device that pierces the seabed through the cone tip.

[0016] like Figure 2As shown, the structures of the first underwater methane sensor segment 201, the second underwater methane sensor segment 202 and the third underwater methane sensor segment 203 are the same. Taking the first underwater methane sensor segment 201 as an example, the first underwater methane sensor segment 201 has first internal threads 29 at both ends, a permeable stone 22 is provided on the left side of the first underwater methane sensor segment 201, and a small hole is provided on the permeable stone 22 to facilitate the ingress and egress of seawater, and a sealing groove 23 is provided on the right side of the permeable stone 22, and a waterproof seal is installed on the sealing groove 23. The first underwater methane sensor section 201 is fixedly welded with a steel plate 25 inside to facilitate the fixation of the methane sensor and the passage of the watertight cable. The methane sensor 27 is fixedly installed on the steel plate 25 by bolts 26. The permeable stone 22 and the first underwater methane sensor section 201 are directly connected to two seawater channel pipes 24 to realize the input and output of seawater. The seawater channel pipes 24 pass through the sealing groove 23 and the steel plate 25 in turn. A porous metal plate 272 is fixedly installed on the inner cavity of the methane sensor 27. The porous metal The plate 272 divides the inner cavity of the methane sensor 27 into two parts, the left part is a seawater storage chamber 271, and the right part is a sensor cavity 274. The seawater storage chamber 271 is located at the tail of the inner cavity of the methane sensor 27. A silicone rubber semipermeable membrane 273 is arranged on the right side of the seawater storage chamber 271. The silicone rubber semipermeable membrane 273 is fixedly mounted on the porous metal plate 272. A semiconductor methane sensor probe 275 is arranged in the sensor cavity 274. The inflowing seawater enters the seawater storage chamber 271 at the tail of the methane sensor 27. The dissolved gas in the water can penetrate into the sensor cavity 274 through the silicone rubber semipermeable membrane 273 supported by the porous metal plate 272, and gradually diffuse in the cavity; there are gas phase and liquid phase gas on the inner and outer sides of the silicone rubber semipermeable membrane respectively; according to Henry's law, in a sealed container at a certain temperature, the partial pressure of the gas is proportional to the molar concentration of the gas dissolved in the solution. When the gas partial pressure on one side is too large, the gas on that side will penetrate through the semipermeable membrane to the other side until the gas partial pressure on both sides of the semipermeable membrane reaches equilibrium. Based on this theoretical foundation, the methane sensor uses its gas sensitivity to methane gas to output a voltage signal through the semiconductor methane sensor probe 275 installed in the sensor cavity 274, and judges the concentration of methane gas that has penetrated into the inner side of the semipermeable membrane according to the change in the voltage signal; the measured methane concentration data is transmitted to the data acquisition section 3 through the watertight cable 28 at the top of the methane sensor 27; like Figure 4As shown, the outer surface of the data acquisition section 3 is a pressure-resistant cabin shell, the right end of the data acquisition section 3 is equipped with a hatch 37, the left end of the data acquisition section 3 is provided with a second internal thread 32 connected to the connecting section 4, and the first internal thread 29 and the second internal thread 32 are respectively provided with a first sealing groove 21 and a second sealing groove 31, and the sealing groove is used for waterproofing. A DC power supply group 33, a data acquisition device 34, a data acquisition control module 35 and a compensating oil tank 36 are installed inside the data acquisition section 3, and the DC power supply group 33 supplies power to the device. The watertight cable 28 is connected to the data acquisition device 34, and the data acquisition device 34 is equipped with an SD card to realize data storage. The data acquisition control module 35 realizes the control of the acquisition time and frequency. The compensation oil tank 36 is configured in the cabin to balance the internal and external pressures and realize the full sea depth deployment of the equipment. A watertight connector 38 is fixedly installed on the hatch 37 and electrically connected to the DC power supply group 33, the data collector 34, and the data acquisition control module 35. The watertight connector 38 mainly realizes data transmission, computer-side control of equipment and battery charging. The hatch 37 has a sealing groove to achieve dryness in the cabin, and the material can withstand pressure at a depth of up to 2000 meters. The data acquisition control module 35 can be set to a self-contained acquisition mode, that is, the probe is connected to the PC, and the acquisition parameters of each methane sensor including sleep time, acquisition time, and acquisition frequency are pre-set through the host computer software, and then the probe is disconnected from the PC and deployed inside the seabed for work. The collected data is stored in the SD card and can be read and exported after the test is completed.

[0017] The specific steps include: S1: The data acquisition control module 35 can be set to a self-contained acquisition mode; the specific steps are: connect the probe rod to the PC, pre-set the acquisition parameters of each methane sensor including sleep time, acquisition time, and acquisition frequency through the host computer software, then disconnect the probe rod from the PC, and deploy it inside the seabed to work. The collected data is stored in the SD card and can be read and exported after the monitoring is completed.

[0018] S2: Insert the methane concentration monitoring probe into the seabed during the migration of shallow seabed gas; S3: The seawater containing dissolved methane slowly penetrates into the methane sensor section through the permeable stone, and the inflowing seawater enters the seawater storage chamber 271 at the tail of the methane sensor. The dissolved gas in the seawater can penetrate into the sensor cavity 274 through the silicone rubber semipermeable membrane 273 supported by the porous metal plate 272, and gradually diffuse in the cavity; there are gas phase and liquid phase gas on the inner and outer sides of the silicone rubber semipermeable membrane respectively; according to Henry's law, in a sealed container at a certain temperature, the molar concentration of the gas in the solution is proportional to the partial pressure of the gas. When the gas partial pressure on one side is too large, the gas on that side will penetrate through the semipermeable membrane to the other side until the gas partial pressure on both sides of the semipermeable membrane reaches equilibrium; the conductivity change produced by the reaction of the oxide semiconductor gas-sensitive material with methane gas is as shown in equation (1), (1) The semiconductor methane sensor probe (275) installed in the sensor cavity outputs a voltage signal, and based on the correction of formulas (2) and (3), the changing voltage signal is converted into an actual methane concentration value, thereby realizing the monitoring of the change of methane concentration over time. The calculation formulas are as follows: (2) (3) in, c is the methane concentration, ; t is the gas temperature, °C; V CH4 is the methane output voltage; V t is the temperature output voltage, V; k 1 - k 9 is a constant obtained through experimental statistical induction.

[0019] At the same time, based on the characteristic changes in methane concentration monitoring data and the response time difference of sensors at different depths, the gas migration rate in the seabed is evaluated.

[0020] In the description of the present invention, the term "plurality" refers to two or more than two. Unless otherwise clearly defined, the orientation or positional relationship indicated by the terms "upper" and "lower" is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation of the present invention; the terms "connection", "installation", "fixation", etc. should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0021] In the description of this specification, the description of the terms "one embodiment", "some embodiments", "specific embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0022] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A quantitative evaluation device for gas migration process in the seabed, wherein the methane concentration monitoring probe for the seabed during the migration of shallow seabed gas comprises a penetration cone tip section (1) and a data acquisition section (3), characterized in that A methane sensor segment (2) is sequentially arranged between the penetration cone tip segment (1) and the data acquisition segment (3), the methane sensor segment (2) comprising a first underwater methane sensor segment (201), a second underwater methane sensor segment (202) and a third underwater methane sensor segment (203), a connecting segment (4) is arranged between the penetration cone tip segment (1), the first underwater methane sensor segment (201), the second underwater methane sensor segment (202), the third underwater methane sensor segment (203) and the data acquisition segment (3), and each segment is connected by a thread; The first underwater methane sensor segment (201), the second underwater methane sensor segment (202) and the third underwater methane sensor segment (203) have the same structure. Both ends of the first underwater methane sensor segment (201) are provided with first internal threads (29). A permeable stone (22) is provided on the left side of the first underwater methane sensor segment (201) and a small hole is provided on the permeable stone (22). A sealing groove (23) is provided on the right side of the permeable stone (22). A rubber strip for waterproofing is installed on the sealing groove (23). A steel plate (25) is fixedly welded inside the methane sensor section (201), and a methane sensor (27) is fixedly mounted on the steel plate (25) by bolts (26). The permeable stone (22) and the first underwater methane sensor section (201) are directly connected to two seawater channel pipes (24) to realize the input and output of seawater. The seawater channel pipes (24) pass through the sealing groove (23) and the steel plate (25) in sequence. The measured methane concentration data is transmitted to the data acquisition section (3) from the top of the methane sensor (27) through a watertight cable (28); A porous metal plate (272) is fixedly mounted on the inner cavity of the methane sensor (27), and the porous metal plate (272) divides the inner cavity of the methane sensor (27) into two parts, the left part is a seawater storage chamber (271), and the right part is a sensor cavity (274), the seawater storage chamber (271) is located at the rear of the inner cavity of the methane sensor (27), a silicone rubber semipermeable membrane (273) is arranged on the right side of the seawater storage chamber (271), and the silicone rubber semipermeable membrane (273) is fixedly mounted on the porous metal plate (272), and a semiconductor methane sensor probe (275) is arranged in the sensor cavity (274); The outer surface of the data acquisition section (3) is a pressure-resistant cabin shell. The right end of the data acquisition section (3) is provided with a cabin cover (37). The left end of the data acquisition section (3) is provided with a second internal thread (32) connected to the connection section (4). The data acquisition section (3) is internally installed with a 12V DC power supply group (33), a data acquisition device (34), a data acquisition control module (35) and a compensating oil tank (36) configured in the cabin. The watertight cable (28) is connected to the data acquisition device (34). The data acquisition device (34) is equipped with an SD card. A watertight connector (38) is fixedly mounted on the hatch cover (37) and is electrically connected to a DC power supply group (33), a data acquisition device (34), and a data acquisition control module (35). The data acquisition control module (35) can be set to a self-contained acquisition mode, that is, the probe is connected to a PC, and acquisition parameters of each methane sensor including a sleep time, an acquisition time, and an acquisition frequency are pre-set through the host computer software. Then, the probe is disconnected from the PC and deployed inside the seabed to work, and the acquired data is stored in an SD card.

2. A device for quantitatively evaluating the gas migration process in the seabed according to claim 1, characterized in that The first internal thread (29) and the second internal thread (32) are respectively provided with a first sealing groove (21) and a second sealing groove (31).

3. The device for quantitatively evaluating the gas migration process in the seabed according to claim 1, characterized in that: The hatch cover (37) has a sealing groove to achieve drying inside the cabin, and the material has a pressure-resistant water depth of up to 2000 meters.

4. A method for quantitatively evaluating the gas migration process in the seabed according to any one of claims 1 to 3, characterized in that: The specific steps include: S1: The data acquisition control module (35) can be set to a self-contained acquisition mode; S2: Insert the methane concentration monitoring probe into the seabed during the migration of shallow seabed gas; S3: The seawater containing dissolved methane slowly penetrates into the methane sensor segment through the permeable stone, and the inflowing seawater enters the seawater storage chamber (271) at the tail of the methane sensor. The dissolved gas in the seawater can penetrate into the sensor cavity (274) through the silicone rubber semipermeable membrane (273) supported by the porous metal plate (272), and gradually diffuse in the cavity; there are gas phase and liquid phase gas on the inner and outer sides of the silicone rubber semipermeable membrane respectively; according to Henry's law, in a sealed container at a certain temperature, the molar concentration of the gas in the solution is proportional to the partial pressure of the gas. When the gas partial pressure on one side is too large, the gas on that side will penetrate through the semipermeable membrane to the other side until the gas partial pressure on both sides of the semipermeable membrane reaches equilibrium; the oxide semiconductor gas-sensitive material will react with methane gas to produce a conductivity change, and the reaction equation is as shown in equation (1), （1） The semiconductor methane sensor probe (275) installed in the sensor cavity outputs a voltage signal, and based on the correction of formulas (2) and (3), the changing voltage signal is converted into an actual methane concentration value, thereby realizing the monitoring of the change of methane concentration over time. The calculation formulas are as follows: （2） （3） in, c is the methane concentration, ; t is the gas temperature, °C; V CH4 is the methane output voltage; V t is the temperature output voltage, V; k 1 - k 9 is a constant obtained through experimental statistical induction; At the same time, based on the characteristic changes in methane concentration monitoring data and the response time difference of sensors at different depths, the gas migration rate in the seabed is evaluated.

5. A method for quantitatively evaluating the gas migration process in the seabed according to claim 4, characterized in that ,The self-contained acquisition mode in step S1 specifically includes the following steps: connect the probe rod to the PC end, pre-set the acquisition parameters of each methane sensor including the sleep time, acquisition time, and acquisition frequency through the host computer software, and then disconnect the probe rod from the PC end, and deploy it inside the seabed for work, and the acquisition data is stored in the SD card, which can be read and exported after the monitoring is completed.

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