JP5263829B2 - Monitoring method and monitoring system of leaked carbon dioxide in subsea reservoir storage - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a monitoring method and a monitoring system of a leaked carbon dioxide stored in a seabed stratum capable of efficiently detecting that the carbon dioxide stored in the seabed stratum is leaked from the sea bottom. <P>SOLUTION: Each undersea acoustic device 10 is installed on the sea bottom so that a sound transmitted from each undersea acoustic device 10 is received by the other undersea acoustic device 10, and it is estimated that the stored carbon dioxide is leaked into the sea from the seabed stratum in a first domain where sea water density is changed based on the information of the transmission/reception of a sound by the undersea acoustic device 10, and a second domain where the stored carbon dioxide is leaked is specified in the first domain by an unroped submersible machine 30, and a spot where the stored carbon dioxide is leaked is specified in the second domain by a roped submersible machine 40. The state of the leaked carbon dioxide is measured periodically and/or continuously at a spot where the stored carbon dioxide is leaked. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a monitoring method and a monitoring system for leaked carbon dioxide in submarine subsurface storage, and is particularly useful when applied to efficiently detect that carbon dioxide stored in the submarine subsurface layer leaks from the seabed. is there.

  In recent years, various efforts have been made to mitigate global warming. For example, energy saving and suppression of carbon dioxide emissions are being carried out. As one of such efforts, various methods (CCS: Carbon Capture and Storage) for collecting and storing carbon dioxide emitted from factories and power plants have been proposed. A method of storing in the seabed underlayer (seabed underlayer storage) has attracted attention as an effective method for reducing carbon dioxide (see, for example, Patent Document 1).

  It is also important to monitor the impact of carbon dioxide on the surrounding environment when implementing submarine subsurface storage. In particular, identifying the location where carbon dioxide stored in the seafloor layer (hereinafter referred to as “stored carbon dioxide”) leaks into the sea is useful for understanding changes in the marine environment. is there. Under such circumstances, it is desired to realize a technique for efficiently detecting a place where stored carbon dioxide is leaking.

  However, the location where the stored carbon dioxide leaks into the sea is determined by empirical rules, and there is an established technology for identifying the location where the stored carbon dioxide leaks from the seabed. The current situation is not. In addition, since it is difficult to identify the leak location, it is difficult to continuously monitor the status of stored carbon dioxide leaked into the sea (hereinafter referred to as “leakage carbon dioxide”). As described above, there is a problem that it is difficult to efficiently detect and measure the leakage location of stored carbon dioxide.

JP 2004-237167 A

  In view of the above prior art, the present invention is a method for monitoring leaked carbon dioxide in submarine substratum storage, which can efficiently detect and monitor that carbon dioxide stored in the submarine substratum leaks from the seabed, and its monitoring The purpose is to provide a system.

  The first aspect of the present invention for achieving the above object is to identify a first region in which a change in seawater density occurs based on information on transmission / reception of sound between a plurality of locations on the seabed. It is estimated that the stored carbon dioxide stored in the seabed underlayer in the region 1 leaks into the sea, and the uncontrolled underwater moving means that is equipped with the carbon dioxide measurement means and operates autonomously is operated in the first area. Based on the measurement result of the measuring means, the region where the leaked carbon dioxide, which is the stored carbon dioxide leaked into the sea, is limited as the second region among the first region, The underwater moving means that is provided with the measuring means and is operated in a roped manner is moved to the second area, and leaked carbon dioxide is detected in the second area based on the measurement result of the measuring means. Identify the area as the leaked point of stored carbon dioxide In methods of monitoring leakage of carbon dioxide in the sub-seabed layer reservoir characterized and.

  In such a first aspect, the first area where the stored carbon dioxide leaks from the sea area over a wide area is estimated, and then the first area is investigated by the unreasonable underwater moving means to identify the second area. Then, after that, the underwater moving means detects the leaked portion of the stored carbon dioxide in the second region. In this way, since the sea area over a wide range is limited to the second area by the acoustic investigation and the unsearched underwater moving means, the underwater moving means can be limited to the second area, Thereby, the leak location of stored carbon dioxide can be detected efficiently.

  According to a second aspect of the present invention, in the monitoring method of leaked carbon dioxide in the submarine underlayer storage described in the first aspect, the leaked location of the stored carbon dioxide is specified, and then periodically or continuously at the leaked location. In the monitoring method for leaked carbon dioxide in the subsea reservoir, the leaked carbon dioxide is measured by the measuring means.

  In the second aspect, it is possible to observe a change in the state of leaked carbon dioxide periodically or over a long period.

  According to a third aspect of the present invention, in the monitoring method for leaked carbon dioxide in the subsea reservoir storage described in the first or second aspect, when the first region is specified, each sound having a different frequency is specified. A method for monitoring leaked carbon dioxide in subsea reservoir storage, characterized in that a region where a change in seawater density occurs is specified and a portion where these regions overlap is defined as a first region.

  In the third aspect, it can be estimated that the probability that the stored carbon dioxide is leaking is higher.

  According to a fourth aspect of the present invention, when the first region is specified in the monitoring method of leaked carbon dioxide in the submarine underlayer storage described in any one of the first to third aspects, Change in seawater density based on the transmission and reception of the sound of the first frequency using the sound of the frequency of the first frequency and the sound of the second frequency different from the first frequency (for example, a frequency lower than the first frequency). If a change in seawater density occurs even when the first region where the occurrence of the seawater occurs is identified based on the transmission / reception information of the sound of the second frequency, the first region is stored in the seabed underlayer. It is in the monitoring method of the leaked carbon dioxide in the seafloor underlayer storage characterized by estimating that the stored carbon dioxide is leaking in the sea.

  In the fourth aspect, it is possible to directly estimate a location where stored carbon dioxide is highly likely to leak.

  According to a fifth aspect of the present invention, a change in seawater density occurs based on a plurality of acoustic transmission / reception means installed on the seabed so that sound can be transmitted / received to each other, and information on the transmission / reception of sound by the acoustic transmission / reception means. A leakage region estimation means for estimating that the stored carbon dioxide stored in the seabed underlayer in the first region is leaked into the sea by specifying one region, and a measurement means for measuring carbon dioxide The unmanned underwater moving means for autonomous and non-operating operation, and the measuring means, and the unmanned underwater moving means for navigating by means of the unmanned underwater movement means, The area where the leaked carbon dioxide, which is the leakage of stored carbon dioxide into the sea based on the measurement result of the measuring means, is limited as a second area, and the cabled underwater moving means is configured as the second area. Based on the measurement result of the measuring means. There are some monitoring system leakage carbon dioxide in the sub-seabed layer reservoir, characterized by identifying the areas where leakage of carbon dioxide is detected as leak portions of the leakage of carbon dioxide.

  In the fifth aspect, the acoustic transmission / reception means estimates the first area where the stored carbon dioxide leaks from the sea area over a wide area, and then the unreached underwater moving means investigates the first area and the second area. Then, the cable-underwater moving means detects the leaked portion of the stored carbon dioxide in the second region. Thus, since the sea area over a wide area is limited to the second area by the acoustic transmission / reception means and the unreasonable underwater movement means, the underwater underwater movement means can be limited to the second area, and can be investigated. Thereby, the leak location of stored carbon dioxide can be detected efficiently.

  ADVANTAGE OF THE INVENTION According to this invention, the monitoring method and the monitoring system of the leaked carbon dioxide in the seabed underlayer storage which can monitor efficiently that the carbon dioxide stored in the seabed underlayer has leaked from the seabed are provided.

It is a figure showing the procedure for implementing the monitoring method of the leaked carbon dioxide in submarine ground layer storage. It is a schematic block diagram of the monitoring system of the leaked carbon dioxide in the seabed underlayer storage which concerns on Embodiment 1 of this invention. It is the schematic which shows the positional relationship of the acoustic transmission-and-reception means arrange | positioned at the seabed, and the leak location of stored carbon dioxide. It is an external view of an acoustic transmission / reception means (underwater acoustic device). It is a whole block diagram of the monitoring apparatus of a leaked carbon dioxide. FIG. 2 is a schematic diagram of a data carrier. It is a figure showing the measurement situation of leaked carbon dioxide using a monitoring device of leaked carbon dioxide. It is a whole block diagram of a submarine installation type automatic elevating device. It is a figure showing the measurement condition of leaked carbon dioxide using a seabed installation type automatic elevating device.

  Hereinafter, the best mode for carrying out the present invention will be described.

<Embodiment 1>
FIG. 1 is a diagram showing a procedure for implementing a method for monitoring leaked carbon dioxide in subsea reservoir storage.

  As shown in the figure, in the monitoring method of the leaked carbon dioxide in the seabed underlayer storage, the leaked location of the stored carbon dioxide is specified (step S10), and the leaked carbon dioxide is measured at the leaked location (step S20).

  Specifically, the leakage location of the stored carbon dioxide is specified by the acoustic tomography technique (step S11), then specified by AUV (Autonomous Underwater Vehicle) (step S12), and further specified by ROV (Remotely Operated Vehicle). (Step S13). In addition, periodic measurement (step S21) and / or continuous measurement (step S22) of the leaked carbon dioxide is performed at the leak location.

  Hereinafter, identification of the leaked location of stored carbon dioxide and measurement of the leaked carbon dioxide will be described in detail.

[Identification of leakage points of stored carbon dioxide]
FIG. 2 is a schematic configuration diagram of a monitoring system for leaked carbon dioxide in the storage of the seabed underlayer, and FIG. 3 is a schematic diagram showing a positional relationship between acoustic transmission / reception means arranged on the seabed and a location where carbon dioxide leaks. .

  As shown in FIG. 2, for example, carbon dioxide discharged from the power generation facility 51 is separated and recovered, and is pressed into the aquifer 53 of the seabed foundation layer in the coastal sea area and isolated to the aquifer 53. . In addition, carbon dioxide may be injected from the bottom of the seabed or from the sea well of an offshore facility (offshore platform).

  The stored carbon dioxide stored in the aquifer 53 in this way is expected to leak out from the crack 15 in the seabed, for example, as shown in FIG. Note that the leaked carbon dioxide is a gas or a liquid. Hereinafter, in the sea area in the vicinity of the crack 15, the monitoring system 1 for leaked carbon dioxide in the undersea reservoir storage, that is, the underwater acoustic device 10 (acoustic transmission / reception means) and information for estimating the location where carbon dioxide is leaking. The identification of the leaked location of the stored carbon dioxide by the processing device 20 (leakage area estimation means), the search-out diving machine (off-line underwater movement means) 30, and the search-out diving machine (search-underwater movement means) 40 will be described. .

  The underwater acoustic device 10 and the information processing device 20 are for specifying the leakage location of stored carbon dioxide using acoustic tomography technology. Specifically, a plurality (five in the illustrated example) of the underwater acoustic devices 10a, 10b, 10c, 10d, and 10e are installed on the ocean floor where the stored carbon dioxide is expected to leak, and each of the underwater acoustic devices 10a. 10e are installed in a state where the absolute position and the relative position of each other are grasped by GPS or the like. These underwater acoustic devices 10 a to 10 e are installed so as to straddle the crack 15.

  As shown in FIG. 4, the underwater acoustic device 10 includes a sound source including a transmitter / receiver 12 that transmits and receives sound of a predetermined frequency, a power supply device, a control device that controls these sound source / power supply devices, and the like in a container 11. It is provided and configured. The container 11 is fixed to the frame 13 and is installed on the seabed via the frame 13 in a state where the transmitter / receiver 12 is turned up, that is, in a state where sound can be transmitted and received over the entire circumference of 360 degrees.

  As shown in FIGS. 2 and 3, relay control means 14 is installed on the seabed. The relay control unit 14 connects the underwater acoustic devices 10a to 10e and the information processing device 20 installed in the monitoring station 50 on the ground, and the information processing device 20 and the underwater acoustic device 10a are connected via the relay control unit 14. Data and control signals can be exchanged with each other.

  The information processing apparatus 20 includes a CPU, a storage unit, and an input / output device. The information processing apparatus 20 transmits a control signal for transmitting sound to the underwater acoustic devices 10a to 10e and is based on data obtained from the underwater acoustic devices 10a to 10e. The calculation which estimates the area | region where stored carbon dioxide is leaking is performed.

  More specifically, the five underwater acoustic devices 10a to 10e emit sound from the transceiver 12 to the other four devices at the same time based on the control signal from the information processing device 20, and the other four devices. The sound from the apparatus is received by the transceiver 12. At this time, the difference between the transmission and reception times is verified for each device, and the region where the seawater density has changed is specified.

  That is, as shown in FIG. 3, when there are leaked portions 54a and 54b where stored carbon dioxide leaks from the crack 15 in the seabed, the positions of the leaked portions 54a and 54b can be estimated as follows. .

  When stored carbon dioxide leaks into the sea as a liquid, the seawater density changes due to changes in the pH of seawater due to the leaked carbon dioxide, changes in the partial pressure of carbon dioxide in seawater, changes in temperature, changes in salinity, changes in the physical properties of the liquid, etc. Arise. For this reason, the density of seawater changes, a difference occurs in the propagation time of sound transmission / reception between the underwater acoustic devices 10a and 10c, and the difference in the propagation time of sound transmission / reception between the underwater acoustic devices 10b and 10e. Thus, the position of the leaked portion 54a can be estimated by analyzing the situation of the time difference. In addition, a difference occurs in the propagation time of sound transmission / reception between the underwater acoustic devices 10b and 10d, and a difference occurs in the propagation time of sound transmission / reception between the underwater acoustic devices 10c and 10e. By analyzing, the position of the leaked portion 54b can be estimated.

  On the other hand, when stored carbon dioxide leaks into the sea as a gas, a strong reflected wave (acoustic scattered wave) due to the bubbles of the leaked carbon dioxide causes a difference in the propagation time of sound transmission and reception between the underwater acoustic devices 10a and 10c. Furthermore, a difference occurs in the propagation time of sound transmission / reception between the underwater acoustic devices 10b and 10e, and the position of the leaked portion 54a can be estimated by analyzing the situation of the time difference. In addition, a difference occurs in the propagation time of sound transmission / reception between the underwater acoustic devices 10b and 10d, and a difference occurs in the propagation time of sound transmission / reception between the underwater acoustic devices 10c and 10e. By analyzing, the position of the leaked portion 54b can be estimated.

  Information on transmission / reception in the underwater acoustic device 10 as described above is sent to the information processing device 20 via the relay control means 14, and the sound propagation information of the underwater acoustic device 10 is analyzed and the stored carbon dioxide leaks. Leaked portions 54a and 54b are estimated. Hereinafter, the vicinity of the leaked portions 54 a and 54 b where the stored carbon dioxide is estimated to be leaked is referred to as a first region 61.

The unsearched submersible 30 is a submarine (AUV: Autonomous Underwater Vehicle) that operates autonomously with no search. Moreover, although not shown in particular, the unsearched diving machine 30 is provided with various measuring means for measuring the leaked carbon dioxide. The cableless submarine 30 navigates in the first area 61, measures the leaked carbon dioxide by the measuring means in the first area 61, and records the measurement result in a storage medium or the like. Examples of the measuring means include a pH sensor and a pCO ₂ (carbon dioxide partial pressure) sensor.

  The pH sensor measures a hydrogen ion index in seawater, and leaked carbon dioxide is detected based on the hydrogen ion index in seawater in the first region 61. Specifically, in the sea area where stored carbon dioxide is leaking, the pH of the seawater is acidic. Therefore, by analyzing the measurement result recorded in the storage medium, it is possible to identify the high and low pH locations in the first region 61, and the stored carbon dioxide leaks at the low pH of the seawater. It can be said that there is a high probability.

The pCO ₂ sensor measures the partial pressure of carbon dioxide in seawater, and leaked carbon dioxide is detected based on the partial pressure of leaked carbon dioxide in seawater in the first region 61. Specifically, in the sea area where stored carbon dioxide leaks, the partial pressure of the leaked carbon dioxide in seawater increases. Therefore, by analyzing the measurement result recorded in the storage medium, it is possible to identify the high and low partial pressures of the leaked carbon dioxide in the first region 61, and the high partial pressure is stored in the storage area. It can be said that there is a high probability that carbon dioxide is leaking.

  Hereinafter, based on the measurement result of the measuring means, the region where the stored carbon dioxide is detected in the first region 61 is referred to as the second region 62.

  The cabled submersible 40 is connected to the mother ship 41 with a cable 42, and is a submerged vehicle (ROV: Remotely Operated Vehicle) that navigates by cable under the control of the mother ship 41. In addition, the cabled submersible 40 is provided with various measuring means for detecting leaked carbon dioxide, like the cableless submersible 30. Under the control of the mother ship 41, the roped submersible 40 performs measurement by the measuring means in the second region 62, and sends the result to the mother ship 41 via the cable 42. Then, in the same manner as the analysis of the measurement result by the measuring means of the unsearched submersible 30 described above, the mother ship 41 analyzes the data measured by the measuring means of the searchable submersible 40, and leaks out of the second region 62. An area where carbon dioxide is detected is identified as a leakage point of stored carbon dioxide.

  As described above, the first region 61 in which the stored carbon dioxide is estimated to be leaked by the acoustic tomography technique is specified, and the uncorrelated submersible 30 (AUV) in the first region 61 is identified. The second area where the stored carbon dioxide leaks is limited, and the leaked portions 54a and 54b of the stored carbon dioxide are specified by the cabled submersible 40 (ROV).

  Here, it is not appropriate to make the unsearched diving machine 30 or the searchable diving machine 40 investigate a wide sea area. This is because the time and cost required for the unsearched submersible device 30 and the searchable submersible device 40 to investigate a wide sea area increase. On the other hand, the underwater acoustic device 10 can have a survey range of 100 km square or more, and can estimate the first region 61 in which stored carbon dioxide leaks from a wide range of sea areas.

  Therefore, first, after the first region 61 is specified using the underwater acoustic device 10, the unsearched submersible 30 measures the first region 61. This means that the area that must be measured can be narrowed down, and the efficiency of the investigation by the unsearched submersible 30 can be improved.

  Further, the roped submersible 40 is controlled by the mother ship 41 via the cable 42, and the navigation range is limited for convenience of transmitting measurement data to the mother ship 41. However, prior to the investigation by the cabled submersible 40, the cabled submersible 30 specifies the second area 62, and therefore the cabled submersible 40 should perform the investigation limited to the second area 62. This makes it possible to more efficiently detect the leaked location of stored carbon dioxide and monitor the leaked carbon dioxide at this leaked location.

  Furthermore, as described above, the monitoring system 1 for leaked carbon dioxide in the subsea reservoir storage of the present invention can detect the leaked portion of the stored carbon dioxide over a wide range of sea areas, and therefore can perform the survey uniformly. . For this reason, it is possible to more accurately evaluate the influence of the stored carbon dioxide stored in the seabed underlayer on the marine environment.

[Measurement of leaked carbon dioxide]
After the stored carbon dioxide leakage points 54a and 54b are specified, the leakage state of the stored carbon dioxide is measured at the leakage points 54a and 54b. Measurement methods are broadly classified into periodic measurement and continuous measurement, and both of them may be performed, or one of them may be performed.

  Periodic measurement is suitable mainly for the purpose of investigating the state of leakage of stored carbon dioxide in the vicinity of the leak locations 54a and 54b. For example, the mother ship 41 is navigated to the leak locations 54a and 54b, and the above-mentioned cabled submersible 40 (ROV) is navigated from the mother vessel 41 into the sea to measure the leakage state of stored carbon dioxide, or the leak location 54a, In the vicinity of 54b, seawater and seabed mud are collected.

  The continuous measurement is mainly suitable for the purpose of investigating a long-term change in the leakage state of the stored carbon dioxide in the vicinity of the leakage points 54a and 54b. For example, it is possible to arrange a device for measuring the leakage status in the vicinity of the leakage locations 54a and 54b and accumulate measurement data regarding the leakage status of stored carbon dioxide. Specific examples of periodic measurement and continuous measurement are shown below.

[Regular measurement]
FIG. 5 shows the overall configuration of a leakage carbon dioxide monitoring apparatus that can perform periodic measurement. As shown in the figure, the mother ship 71 navigating offshore knows the current position on the earth by the GPS 72, and various information is displayed on the instruction / display CPU 73. The mother ship 71 is provided with a towed body 75 towed by a towline 91 in the sea at a predetermined depth (for example, 2 m which is a depth that is not affected by sea surface waves). It is designed to maintain a horizontal posture at depth. For example, the towed body 75 is towed in a state in which the horizontal posture is maintained at a position about 200 m away from the mother ship 71 and the abdomen of the towed body 75 receives and transmits data as transmission / reception means for receiving and transmitting data. A wave device 79 is attached.

  A branching rope 92 is connected to the towing line 91 on the front side of the towing body 75 (for example, about 5 m ahead in the horizontal distance), and an offshore towing body 74 towed on the ocean is connected to the branching line 92. That is, the towed body 75 and the offshore towed body 74 are towed to the mother ship 71 by the towed rope 91 and the branching cable 92. As with the mother ship 71, the offshore towed body 74 has a current position on the earth grasped by the GPS 72, and the mother ship 71 and the offshore towed body 74 can wirelessly communicate with each other via the wireless means 77. The offshore towed body 74 maintains buoyancy at the sea level, and a pole 78 that functions as a keel is provided below the sea level.

  The transmitter / receiver 79 of the towed body 75 and the wireless means 77 of the offshore towed body 74 are connected by a communication cable 94 to perform wired communication. Various data signals received by the transmitter / receiver 79 are sent to the offshore towed body 74 via the communication cable 94, and sent to the CPU 73 of the mother ship 71 via the wireless means 77.

  On the other hand, from the rear part of the mother ship 71, the wire 81 is lowered into the sea. At the tip of the wire 81, the wire 81 maintains a predetermined range of depth (for example, a maximum of 3000 m) in the length direction and is in a predetermined range. A weight 80 is attached to keep the towed and towed. The towed body 75 and the offshore towed body 74 are towed by the mother ship 71 through the towline 91 and the branch line 92, and the wire 81 is towed in the sea in a range of a predetermined depth.

  Five data carriers 82 are attached to the wire 81, and the five data carriers 82 are maintained in, for example, the middle layer in the sea (for example, 1000 m to 3000 m). Although details will be described later, the data carrier 82 is provided with a transmitting means for transmitting a data signal by acoustic communication, a field measuring instrument, a collecting means, a data storing means, and the like.

The number of data carriers 82 is not limited to five, and two to four, or a plurality of six or more may be provided.

  FIG. 6 is a schematic diagram of a data carrier. As shown in the figure, a frame-like gantry 85 is attached to the wire 81, and a transmission means 87 is supported on the gantry 85 via a rope 86. The transmission means 87 is provided with a depth meter (not shown). As shown in FIG. 5, the transmission means 87 transmits data to the mother ship 71 via the towed body 75 and the offshore towed body 74, the towed body 75 and the offshore. A command is received from the mother ship 71 via the towed body 74.

At the upper part of the gantry 85, a water sampler 96 for collecting seawater by remotely opening and closing a valve, a storage means 97 for storing measured data, a battery 98 as a power source for various devices, and a partial pressure of carbon dioxide are detected. A sensor unit 93 that stores measurement means such as a pCO ₂ sensor (carbon dioxide partial pressure sensor) is provided.

  As shown in FIG. 7, the stored carbon dioxide leaking portion 54 a specified by the underwater acoustic device 10 (see FIG. 2), the unsearched diving machine 30 (see FIG. 2), and the cabled submersible 40 (see FIG. 2) The mother ship 71 is navigated so as to move the data carrier 82, and the diffusion state of the leaked carbon dioxide 55 at a predetermined depth is detected. That is, with the weight (see FIG. 5), the data carrier 82 is maintained at a predetermined depth and posture at a predetermined depth, and the mother ship 71 is navigated so as to repeatedly reciprocate at a predetermined distance on the surface of the leaked portion 54a. Then, the diffusion state of the leaked carbon dioxide 55 at a predetermined depth is detected.

  The distribution / behavior of carbon dioxide diffusion is tracked by acoustic communication with the data carrier 82 towed by the mother ship 71, and the distribution / behavior of dilution / diffusion of the leaked carbon dioxide 55 in a predetermined ocean middle layer is derived. At this time, the mother ship 71 tows the towed body 75 and the offshore towed body 74 and tows the wire 81 in a state in which the data carrier 82 is maintained in a predetermined ocean middle layer by the weight 80. The positional relationship among the mother ship 71, the offshore towed body 74, and the data carrier 82 is always grasped by the GPS 72.

The navigation route of the mother ship 71 is appropriately controlled, and various devices are operated in conjunction with information on the field measuring instrument (sensor unit 93, pCO ₂ sensor) of the data carrier 82 to detect the distribution / behavior of the leaked carbon dioxide 55. To do. Further, seawater is collected by opening and closing a water sampler 96 that collects seawater by remote operation of a valve, or stored in storage means 97 that stores data measured by an on-site measuring instrument. By collecting desired seawater with the water sampler 96, it is possible to carry out an investigation of ecosystems such as living organisms, and it is also possible to use it as an index for dilution / diffusion of the leaked carbon dioxide 55.

  Information on the leaked carbon dioxide 55 is sent from the transmission means 87 to the transducer 79 of the towing body 75, and is sent from the transducer 79 to the offshore towing body 74 via the communication cable 94. The information on the leaked carbon dioxide 55 is sent to the CPU 73 of the mother ship 71 by the wireless means 77 of the offshore towed body 74, and the distribution / behavior of the leaked carbon dioxide 55 is grasped by the CPU 73. -Behavior is derived.

  Data on the diffusion of the leaked carbon dioxide 55 from the transmission means 87 of the data carrier 82 towed to the sea layer at a predetermined depth is sent to the transmitter / receiver 79 of the towed body 75 and communicated from the transmitter / receiver 79 of the towed body 75. The diffusion data of the leaked carbon dioxide 55 is transmitted to the offshore towed body 74 through the cable 94. Then, the diffusion data of the leaked carbon dioxide 55 is sent from the offshore towed body 74 to the mother ship 71 by the wireless means 77, and the situation of the dilution / diffusion distribution and behavior of the leaked carbon dioxide 55 is derived.

  Communication between the transmission means 87 of the data carrier 82 and the transmitter / receiver 79 of the towed body 75 is performed by acoustic communication, and the towed body 75 is towed in the sea. The influence of waves near the sea surface is eliminated, and the data on the diffusion of the leaked carbon dioxide 55 can be transmitted and received in a stable state. Since the transmission / reception means is towed in the sea, the influence of the noise of the mother ship 71 can be suppressed, and the influence of waves near the sea surface is eliminated, and leakage between the transmission means 87 and the transmitter / receiver 79 is stable. Data on the diffusion of carbon dioxide 55 can be transmitted and received.

[Continuous measurement]
FIG. 8 shows the overall configuration of a submarine automatic lifting device capable of continuously measuring the leakage state of stored carbon dioxide. As shown in the figure, a submarine automatic lifting apparatus 100 is equipped with a measuring device 101 such as a pH sensor, a pCO ₂ sensor, a depth meter, and a recording device 102 that records measurement data of the measuring device 101. It has a buoy 103. The elevating buoy 103 is connected to a winch drum 105 attached to the frame 104 via a wire 106. Further, a control device 107 and a battery 108 are attached to the frame 104, and the winch drum 105 is driven by the battery 108, and can wind or feed a wire based on a signal from the control device 107. ing.

  As shown in FIG. 9A, the above-described seabed-mounted automatic lifting apparatus 100 is fixed to the seabed near the leaked portion 54 a of the leaked carbon dioxide 55. Then, at a preset time, the control device 107 transmits a signal for feeding the wire 106 to the winch drum 105. The winch drum 105 feeds the wire 106 based on the signal, so that the elevating buoy 103 is separated from the frame 104 and is located in the sea. The submarine automatic lifting apparatus 100 is not limited to the case where the frame 104 is fixed to the seabed, but a wire 109 is attached to a fixing part 110 installed on the seabed, and the frame 104 is moored to the wire 109, thereby You may make 104 the state which floated in the sea. Thereby, the measurement by the raising / lowering buoy 103 can be performed on the sea surface side.

  After the wire 106 is unwound by a predetermined distance, the control device 107 transmits a signal for winding the wire 106 to the winch drum 105. The winch drum 105 winds the wire 106 on the basis of the signal, so that the lifting buoy 103 is fixed to the frame 104 again. It should be noted that conditions for feeding and winding the wire 106, such as the time to feed the wire 106 and the length to feed the wire 106, are preset in the control device 107 on the ocean.

  Such a submarine installation type automatic elevating device 100 can measure the state of seawater in the depth direction with one elevating buoy 103, and therefore has an advantage that the cost and the apparatus configuration are not complicated. If a plurality of measuring devices corresponding to the lifting buoy 103 are installed in the sea at a predetermined depth, the cost increases, and the configuration of each measuring device becomes complicated.

  As described above, since the lifting buoy 103 is moved in the depth direction in the vicinity of the leaked portion 54a by feeding and winding the wire 106 by the winch drum 105, the state of the seawater at each depth is measured by various sensors. The measured value is periodically recorded in the recording device 102. That is, the state of the leaked carbon dioxide is recorded in the recording device 102 in time series, and the state of the leaked carbon dioxide in a wide range in the depth direction is recorded spatially. Therefore, by collecting the recording apparatus 102 after a predetermined period of time and analyzing the measurement data, the diffusion state of the leaked carbon dioxide, that is, in which direction the leaked carbon dioxide 55 leaked from the leaked portion 54a is directed in a long direction. , It is possible to grasp the depth of diffusion and how much is diluted.

  Note that the measurement data recorded in the recording device 102 of the lift buoy 103 is not limited to being collected after a predetermined period. As shown in FIG. 9B, a repeater (not shown) that receives measurement data recorded in the recording device 102 via sound waves is provided in the frame 104, and the relay control device 14A installed on the sea floor The measurement data may be collected from each repeater of each submarine automatic lifting device 100 and transmitted to the information processing device of the land monitoring station 50 so that the measurement can be performed in real time.

<Other embodiments>
As the frequency of the sound used by the underwater acoustic device 10, sounds having a plurality of different frequencies may be used. The underwater acoustic device 10 generates a sound and receives the sound to identify a region where the density change of the seawater occurs. Generally, the higher the sound frequency, the more sensitively detects the density change of the seawater. be able to. Therefore, if the sound of the stored carbon dioxide leaks for each sound of each frequency using sounds of different frequencies, and the leaked location of the stored carbon dioxide estimated for each sound matches, The probability that the stored carbon dioxide is leaking can be estimated to be higher.

  Moreover, it is difficult to directly observe the leakage of stored carbon dioxide by transmitting and receiving sound by the underwater acoustic device 10 itself. However, it is also possible to directly estimate the location where the stored carbon dioxide is leaking by using sound of a plurality of different frequencies from the underwater acoustic device 10.

  More specifically, as described above, the density change of seawater can be detected with higher sensitivity as the sound frequency is higher. Therefore, when observing changes in seawater density due to high-frequency sound, changes in seawater density are observed with high sensitivity.

  On the other hand, if the change in seawater density is observed with low-frequency sound, it should be difficult to detect the change in seawater density. Nevertheless, if a change in seawater density is detected, it is considered that the change was detected due to the leakage of stored carbon dioxide. From this, if a change in seawater density can be detected with low-frequency sound, it can be estimated that stored carbon dioxide is leaking.

Moreover, as a measuring means of the leaked carbon dioxide using the unsearched submersible 30 or the cabled submersible 40, or a measuring means when measuring the leaked carbon dioxide periodically or / and continuously at the leaking points 54a and 54b, The pH sensor and the pCO ₂ sensor are exemplified, but not limited thereto. For example, an imaging device, a water intake device, or a mud sampling device can be used as the measuring means. The stored carbon dioxide leaking through the image obtained from the imaging device is detected visually, or the water directly taken by the water intake device is analyzed by an analysis means to detect the presence or absence of stored carbon dioxide, or the diffusion of the leaked carbon dioxide The situation can be grasped. Similarly, it is also possible to detect whether or not the stored carbon dioxide has leaked by analyzing what has been directly collected by the mud collecting apparatus using an analysis means, and to grasp the diffusion state of the leaked carbon dioxide.

  The underwater acoustic device 10 does not have to send data to the information processing device 20 in real time. Each underwater acoustic device 10 includes a data storage unit, and the first region 61 is separately analyzed by analyzing data in a predetermined period. May be specified. It is also possible to detect discontinuous changes over time by detecting leakage of stored carbon dioxide in units of days, weeks, months, and years.

  The relay control unit 14 is connected to the information processing device 20 of the monitoring station 50 to exchange information. However, the relay control unit 14 and the underwater acoustic device 10 are equipped with a large-capacity power source and connected by a cable or the like. It is also possible to exchange information with the underwater acoustic device 10 by wireless communication. In this case, in order to synchronize the time at which each underwater acoustic device 10 transmits sound, each underwater acoustic device 10 is provided with synchronization means such as an atomic clock.

  INDUSTRIAL APPLICABILITY The present invention can be used in the industrial field for efficiently detecting a location where stored carbon dioxide in the seabed underlayer storage leaks from the seabed.

DESCRIPTION OF SYMBOLS 1 Monitoring system 10 Underwater acoustic apparatus 11 Container 12 Transmitter / receiver 13 Frame 14 Relay control means 15 Crack 20 Information processing apparatus 30 Unsearched submersible machine 40 Rope submersible machine 41, 71 Mother ship 42 Cable 50 Monitoring station 51 Power generation equipment 52 Pipeline 53 Aquifer 54a, 54b Leakage location 55 Leakage carbon dioxide 61 First region 62 Second region 74 Offshore towed body 75 Towed body 79 Transceiver 82 Data carrier 87 Transmitting means 100 Submarine automatic lifting device 101 Measuring equipment 102 Recording device 103 Lifting buoy

Claims (5)

A first region in which a change in seawater density occurs is identified based on information on transmission and reception of sound between a plurality of locations on the seabed, and the stored carbon dioxide stored in the seafloor underlayer in the first region is in the sea Presumed to be leaking to
An uncontrolled underwater moving means that includes a measuring means for carbon dioxide and operates autonomously without movement is moved to the first area, and based on the measurement result of the measuring means, the stored carbon dioxide in the first area The area where the leaked carbon dioxide, which was leaked into the sea, was limited as the second area,
The underwater moving means that is provided with the measuring means and is operated in a roped manner is moved to the second area, and leaked carbon dioxide is detected in the second area based on the measurement result of the measuring means. A method for monitoring leaked carbon dioxide in subsea reservoir storage, wherein an area is specified as a leak point of stored carbon dioxide. In the monitoring method of the leaked carbon dioxide in the seabed underlayer storage according to claim 1,
A method for monitoring leaked carbon dioxide in subsea reservoir storage, wherein after the leaked location of stored carbon dioxide is identified, the leaked carbon dioxide is measured periodically or continuously at the leak location. In the monitoring method of the leaked carbon dioxide in the seabed underlayer storage according to claim 1 or claim 2,
When specifying the first region, a region where a change in seawater density occurs for each sound having a different frequency is specified, and an overlapping part of these regions is defined as the first region. Monitoring method for leaked carbon dioxide in subsea reservoir storage. In the monitoring method of the leaked carbon dioxide in the seabed foundation layer storage according to any one of claims 1 to 3,
When the first region is specified, a sound having a first frequency and a sound having a second frequency different from the first frequency are used, and the seawater density is determined based on transmission / reception of the sound having the first frequency. When the first region in which the change in the sea level occurs is specified and the seawater density has changed even on the basis of the information on the transmission and reception of the sound of the second frequency, A method for monitoring leaked carbon dioxide in subsea reservoir storage, wherein the stored carbon dioxide is estimated to be leaking into the sea. A plurality of acoustic transmission / reception means installed on the seabed so that sound can be transmitted and received between each other;
By identifying the first region where the seawater density changes based on the sound transmission / reception information by the acoustic transmission / reception means, the stored carbon dioxide stored in the seabed underlayer leaks into the sea in the first region. Leakage area estimation means for estimating
A no-underwater moving means that has a measuring means for measuring carbon dioxide and autonomously operates without being searched,
Having the measuring means, and equipped with an underwater moving means that operates by means of a cable;
The unreasonable underwater moving means limits, as the second area, an area in which the leaked carbon dioxide, in which the stored carbon dioxide has leaked into the sea based on the measurement result of the measurement means, is detected in the first area. And
The underwater moving means identifies an area where leaked carbon dioxide is detected based on a measurement result of the measuring means as the leaked location of leaked carbon dioxide in the second area. Monitoring system for leaked carbon dioxide in geological storage.

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