JP5223532B2 - Water column observation apparatus and method - Google Patents

Description

  The present invention relates to a water column observation apparatus and a water column observation method capable of observing in real time without requiring a large number of acoustic video imaging devices.

  In marine development, as environmental pollution countermeasures, it is necessary to conduct a marine environment survey before the start of development and to conduct a marine environment survey during development and during production operation after the end of development to investigate changes in the marine environment. Marine environment surveys are also conducted for other purposes such as volcanic activity surveys.

  In the marine environment survey accompanying marine development, the platform is moored on the ocean for the purpose of marine development and production, so environmental monitoring of the water column area from the development floor / production site to the sea surface around the platform is performed in real time. It is desirable. Here, the water column refers to a three-dimensional space obtained by extending a predetermined horizontal region, for example, a circular region having a certain radius in the vertical direction (hereinafter, referred to as the up-down direction).

  Conventionally, when measuring physical quantity distribution in a water column, a fixed-point measurement method that measures physical quantities at multiple locations at different water depths by attaching multiple physical quantity sensors at intervals in the longitudinal direction of the rope, automatic without self There is an underwater robot measurement method in which a submersible robot (underwater navigation body) that sinks and floats is navigated and a physical quantity in a water column is measured.

  Among physical quantity sensors, examples of physical quantity sensors that measure acoustic scatterers (backgrounds, solids, organisms, gases, etc.) include underwater cameras and acoustic video imaging devices called ambient monitoring sonars.

Japanese Patent Laid-Open No. 7-245857

  In the fixed point measurement method, for example, in a deep sea exceeding a water depth of 1000 m, when a water column from the sea floor to the sea surface is targeted, it is necessary to install a large number of physical quantity sensors. Further, when measuring the physical quantity distribution with fine resolution in the vertical direction, it is necessary to install a large number of physical quantity sensors in the vertical direction according to the resolution.

  In the underwater robot measurement method, since the underwater robot is unreasonable, information transmission by underwater acoustic communication is required to observe in real time on the water. However, in underwater acoustic communication, it is difficult to transmit a large amount of data such as audio-visual electronic information in real time. Real-time observation is not possible with the batch processing method in which audio-visual electronic information is accumulated and collected at the time of ascent. In addition, since it takes time for the underwater robot to make a round trip between the ocean and the deep ocean, it takes a long time to take an acoustic image and reproduce it for actual observation in the batch processing method. .

  Considering physical quantity sensors, underwater cameras require a light source in the deep sea. In both the fixed point measurement method and the underwater robot measurement method, since the light source is mounted, the apparatus becomes complicated and heavy, and power consumption of the light source occurs. In addition, it is difficult to shoot a clear image in a muddy water area near the sea floor when shooting an optical image with an underwater camera.

  In recent years, the acoustic video imaging apparatus can capture a clear acoustic image. The acoustic image pickup device does not require a light source and is not affected by muddy water. The acoustic image pickup device can pick up a sound image that is clear enough for an observer to visually analyze if it is in the vicinity of several tens of meters. In addition, it is possible to detect an acoustic scatterer several hundred meters away, although the resolution is lowered.

  In order to increase the resolution, the beam (detection directivity) of an acoustic image pickup device generally called an ambient monitoring sonar has a narrow width. The beam of the audio / video imaging device (hereinafter, referred to as a surrounding monitoring sonar) has a beam shape that is narrow in width and opened in a fan shape at a predetermined angle vertically. In other words, the audio video imaging device is narrow and can pick up an acoustic image in a fan-shaped range vertically. Furthermore, this type of audio-visual imaging device performs imaging while mechanically or electronically rotating a beam around a vertical rotation axis. Thereby, a beam can be rotated by a predetermined angle (around 360 °) in the horizontal direction, and a surrounding acoustic image can be captured.

  However, there is a limit to the observable range in the vertical direction by the audio video imaging device. For this reason, when targeting a wide range in the vertical direction like a water column, the above-described fixed point measurement method and underwater robot measurement method must be employed.

  It is also conceivable to carry out horizontal scanning with an acoustic imaging device mounted on a watercraft and with the beam directed downward. This is the same principle as a fish detector. However, if a watercraft navigates around the platform 24 hours a day, 365 days a year, it will be an obstacle for the mooring of the platform and a ship that transports materials and human resources to the platform. In addition, since the resolution in the deep sea is low when observed from the water, it is not suitable when the observation target is in the deep sea.

  Therefore, an object of the present invention is to provide a water column observation apparatus and a water column observation method that solve the above-described problems and that can be observed in real time without requiring a large number of acoustic video imaging devices.

In order to achieve the above object, an underwater observation apparatus according to the present invention includes a water buoy, a hoist mounted on the water buoy, a suspension rope suspended from the hoist, and the suspension rope. and audio-visual imaging device attached to imaging the periphery of the audiovisual while rotating around the vertical axis of rotation, the vertically moving the acoustic image pickup device in a water depth interval by controlling the hoisting machine The lifting controller for picking up the sound image of the bubbles in the water column, the transmission cable for transmitting the sound image electronic information from the sound image pickup device to the water buoy, and the sound image electronic information mounted on the water buoy. And a wireless transmission device for wireless transmission.

  The acoustic video imaging device may be attached to the suspension cable via a gimbal in order to hold the posture in the vertical direction.

Further, the underwater observation method of the present invention includes an acoustic video imaging device that images a surrounding acoustic video while rotating about a vertical rotation axis on a suspension rope suspended from a hoist mounted on a water buoy. mounting, by vertically moving the acoustic image pickup device by controlling the hoisting machine in the water depth interval imaging and audio-visual bubble groups water column around the depth interval of said audio visual imaging equipment, Audio video electronic information from the audio video imaging device is transmitted by a transmission cable and a wireless transmission device .

  An acoustic image of the bubble group may be extracted from the acoustic image, and the amount of leaked gas may be estimated from the scale information and the scattering intensity of the bubble group acoustic image.

  The present invention exhibits the following excellent effects.

  (1) A large number of audio-visual imaging devices are not required.

  (2) Real-time observation is possible.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  As shown in FIG. 1, a water column observation device 1 according to the present invention includes a water buoy 2, a hoisting machine 3 mounted on the water buoy 2, and a suspension rope 4 suspended from the hoisting machine 3. An acoustic image pickup device 5 that is attached to the suspension cable 4 and picks up surrounding sound images; and a lift controller 6 that controls the hoist 3 to move the sound image pickup device 5 up and down in a desired water depth section; , A transmission cable 7 for transmitting the acoustic video electronic information from the acoustic video imaging device 5 to the water buoy 2 and a wireless transmission device 8 mounted on the water buoy 2 for wirelessly transmitting the acoustic video electronic information. .

  The water buoy (ambient observation buoy) 2 is a floating body that is known per se and is floating at a fixed point on the sea. The water buoy 2 has a waterproof space for mounting the elevation controller 6, the wireless transmission device 8, and these power supplies.

  The hoisting machine (winch) 3 is used for lowering and hoisting the suspension cable 4, and includes a power source, a motor, and a drum (not shown). The hoisting machine 3 may be configured to wind down and wind up the transmission cable 7 together with the suspension cable 4. The hoisting machine 3 may be configured to be able to measure the water depth of the audio video imaging device 5 from the feeding length (or the integration of the feeding speed) of the suspension cable 4.

  The suspension cable 4 is a suspension cable 4 having a strength capable of suspending a predetermined payload up to a conventional deep sea. The suspension cable 4 may be integrated with the transmission cable 7.

  As described above, the audio video imaging device 5 has a narrow width called a beam and can pick up an acoustic image in a fan-shaped range vertically. By performing imaging while rotating the beam around the rotation axis standing in the vertical direction, a high-resolution acoustic image can be captured about 360 ° around the rotation axis. The acoustic image pickup device 5 is a type in which an acoustic sensor having a predetermined beam shape is mechanically rotated or a large number of small acoustic sensors are arranged in the circumferential direction and the vertical direction, and phase control is performed on each acoustic sensor, There is a type that can control the beam width, vertical angle, and beam rotation angle.

  The raising / lowering controller 6 gives the hoisting amount to the hoisting machine 3 so that the audio and video imaging device 5 repeatedly moves up and down a desired water depth section. It is preferable that the elevating controller 6 is also provided with a lowering speed and a hoisting speed for the hoisting machine 3. The elevation controller 6 may include a depth meter that measures the water depth of the audio / video imaging device 5 and a USBL that measures the relative position of the water buoy to confirm the elevation control result of the audio / video imaging device 5. The elevation controller 6 may use the water depth of the audio / video imaging device 5 measured by the hoisting machine 3.

  The transmission cable 7 is a conventionally known underwater cable. The transmission cable 7 has a transmission capacity that is high enough to transmit high-resolution audio-visual electronic information in real time.

  The wireless transmission device 8 performs wireless communication directly or via a satellite relay to a monitoring device installed outside a platform, a mother ship, a remote land facility, etc. (not shown). The wireless transmission device 8 has a transmission capacity that is high enough to transmit high-resolution audio-visual electronic information in real time.

  In addition, the water column observation device 1 is equipped with a marine weather observation device, a radio warning signal transmitter as a means for preventing anti-ship collision, a light, a positioning device, and the like on the water buoy 2.

  In the embodiment of FIG. 1, in the water column observation device 1, a physical quantity sensor group 9 for observing a plurality of types of physical quantities other than an acoustic image is attached to the lower end of the suspension cable 4, and a gimbal 10 is attached to the lower end of the physical quantity sensor group 9. The acoustic image pickup device 5 is attached to the lower end of the gimbal 10.

  The physical quantity observed by the physical quantity sensor group 9 includes water temperature, depth, flow velocity / flow direction, water pressure, specific gravity, pH, spectral spectrum, USBL system positioning amount, and the like. The USBL (Uitra Short Base Line) type positioning amount is a positioning amount obtained by calculating the earth coordinates of a physical quantity sensor by obtaining a relative position by acoustic detection between a fixed point whose earth coordinates are known and a physical quantity sensor in water.

  The gimbal 10 is provided so that the posture of the acoustic image pickup device 5 is kept vertical even when the suspension cable 4 is inclined due to the flow of tide.

  Hereinafter, the water column observation method of the present invention will be described.

  In the present embodiment, a plurality of the water column observation devices 1 described so far are arranged around the platform. In addition, when the radius of the water column to be observed is small, high-resolution observation is possible only by arranging one water column observation device 1 under the platform. By observing the water column around each of them with a plurality of water column observation devices, a wide area around the platform can be observed.

  In the water column observation device 1, an acoustic video imaging device 5 that captures a surrounding acoustic video is attached to a suspension rope 4 suspended from a hoisting machine 3 mounted on a water buoy 2. In this state, the hoisting machine 3 is controlled by the elevating controller 6, and the audio / video imaging device 5 is moved up and down in a desired water depth section.

  The acoustic video imaging device 5 stops and moves at predetermined water depths while moving up and down, and images surrounding acoustic video while rotating the beam continuously in time. Thereby, the acoustic image of the three-dimensional space (that is, the desired water column) around the acoustic image capturing device 5 and included in the water depth section is continuously scanned in the circumferential direction while being continuously scanned in the circumferential direction. Can do.

  The audio video electronic information output from the audio video imaging device 5 is transmitted to the water buoy 2 via the transmission cable 7 in real time. In the water buoy 2, the wireless transmission device 8 wirelessly transmits the acoustic video electronic information transmitted from the acoustic video imaging device 5 via the transmission cable 7 to the outside in real time.

  A monitoring device installed in a platform, mother ship, remote land facility, or the like displays an audio image on an image display based on the audio image electronic information. Since the resolution of the audio video is high, the image display device displays a sound image that is clear enough to be visually analyzed by the observer. The monitoring device can also perform appropriate image processing, feature extraction, automatic analysis, and the like based on the audio video electronic information.

  As the contents of the analysis, for example, the acoustic image of the bubble group is extracted from the acoustic image of the entire water column, and the leaked gas amount is estimated from the scale information (height and width) and the scattering intensity of the extracted bubble group acoustic image. To do.

  Here, the estimation of the leakage gas amount will be described in detail.

  In the case of natural gas, generally, there is a depth of several thousand meters from the bottom of the sea to the natural gas reserve, and the natural gas is covered with a thick bedrock, so there is no gas leakage from the sea floor. However, when natural gas or other gas is buried in a shallow area of several hundred meters from the sea bottom, gas leakage from the sea bottom may occur. Further, when a failure occurs in the riser pipe, which is a pipe for transporting natural gas from the sea floor to the sea, natural gas may leak from the riser pipe. In some cases, the cementing reinforced to cover the sea floor may crack and cause gas leakage. In some cases, gas erupting from mud volcanoes on the seabed is actually observed.

  The gas leaked from the seabed rises while diffusing as bubbles in the sea. Bubbles grow high in a cloud-like state. Such a bubble group is called a gas plume. Gas has the property of slowly dissolving in seawater over time. Thus, the bubbles gradually shrink and disappear as they rise. For this reason, the gas plume grows at a certain height from the seabed, but stops at a certain height. That is, the top is formed in the gas plume. When there is a large amount of leaked gas, the bubbles diffuse widely and the time until disappearance is long, so the shape of the gas plume, that is, the height and width differ depending on the amount of leaked gas.

  On the other hand, bubbles in the sea have the property of reflecting (scattering) sound that has propagated through the sea. Therefore, bubbles can be detected by emitting sound into the sea and capturing scattered waves from the bubbles. This is the principle of the audio video imaging device 5. When the sound hits a gas plume, which is a bubble group of bubbles, the acoustic image due to the scattered waves becomes an acoustic image with a vague outline like a cloud.

  By the way, when the sound hits a hard object such as the seabed (elevation) or an artifact, the image of the scattered wave becomes clear. If the sound passes through a place where there is neither a gas plume nor a solid object, the reflected wave does not return, so an acoustic image with special characteristics cannot be obtained. Therefore, the gas plume can be detected by observing the acoustic image.

  FIG. 2 shows an example of an audio image. The vertical axis is the water depth, and the horizontal axis is the reflection distance. The reflection distance is obtained from the acoustic reflection time. FIG. 2 shows a vertical scan for a specific beam rotation angle.

  As shown in the figure, the acoustic video G by the gas plume shows the horizontal distance from the acoustic video imaging device 5 to the gas plume and the scattering intensity of the gas plume. In the observation of the gas plume, it is important to know the height and width of the gas plume. Since the distance is measured, the height / width and scattering intensity of the gas plume can be detected.

  As described above, since the height / width and scattering intensity of the gas plume differ depending on the amount of leaked gas, the leaked gas is determined from the height / width and scattering intensity of the gas plume obtained by observing the acoustic image G by the gas plume. The amount can be estimated. For example, by observing an acoustic image of a gas plume with a known amount of leaked gas, a database representing the correspondence between the scattering intensity per unit area of the gas plume and the amount of leaked gas was created and then observed. The amount of leaked gas is estimated by referring to the database from the scattering area and scattering intensity of the gas plume calculated from the scale information (height and width) of the gas plume.

  As described above, the water column observation device 1 of the present invention uses only one acoustic image capturing device 5. It is sufficient for the physical quantity sensor group 9 to have one physical quantity sensor for one kind of physical quantity. The conventional fixed point measurement method is expensive because a large number of physical quantity sensors are installed when targeting a deep water column or measuring the physical quantity distribution with a fine vertical resolution, but the present invention provides an acoustic image. The number of physical quantity sensors such as the imaging device 5 can be reduced, and the water column observation device 1 becomes inexpensive.

  Since the water column observation device 1 of the present invention transmits the audio video electronic information from the audio video imaging device 5 by the transmission cable 7 and the radio transmission device 8, it has a high resolution audio image that is continuous in time. A large amount of audiovisual electronic information can be transmitted in real time. The conventional underwater robot measurement method uses underwater acoustic communication that cannot transmit a large amount of data, so high-resolution audio images cannot be obtained, or real-time observation cannot be performed using a batch processing method. Real-time observation with high-resolution audio images is possible. As a result, continuous physical quantity monitoring and evaluation of water columns can be performed in real time, which is effective in grasping the situation at development sites and production sites in the deep sea.

  In the water column observation apparatus 1 according to the present invention, since the lifting controller 6 gives the hoisting machine 3 the amount of lowering and hoisting, an arbitrary water depth section can be realized as necessary. In the conventional fixed point measurement method, it is necessary to re-install the physical quantity sensor in order to change the water depth section, but in the present invention, the elevation controller 6 only needs to change the control amount, so the water depth section can be changed easily. be able to. Further, if the elevating controller 6 is also provided with a lowering speed and a hoisting speed for the hoisting machine 3, the vertical scanning speed can be arbitrarily set.

  Thereby, the resolution of the physical quantity distribution in the vertical direction can be adjusted to be coarse or fine. In the conventional fixed point measurement method, it is necessary to re-install the physical quantity sensor by changing the installation interval of the physical quantity sensor. However, in the present invention, since the elevation controller 6 only needs to change the control quantity, The resolution can be changed easily. You may make it instruct | indicate the control amount in the raising / lowering controller 6 from the exterior of a platform etc. to the raising / lowering controller 6 via the wireless transmission apparatus 8. FIG.

  The water column observation apparatus 1 according to the present invention is not limited to the case where the suspension cable 4 is suspended vertically, but also when the suspension cable 4 is inclined due to the flow of the tide, the gimbal 10 functions to produce the audio video imaging device 5. Always keep vertical, so the beam rotation axis keeps vertical. Therefore, the center of the beam is always directed horizontally. As a result, the physical quantity distribution of the water column can be observed with high positional accuracy.

  Since the water column observation apparatus 1 of the present invention extracts the acoustic image of the bubble group from the acoustic image and estimates the leaked gas amount from the height and width of the bubble group acoustic image, the early detection of the gas leak and its It is effective for monitoring the diffusion status.

It is a side view of the water column observation apparatus which shows one Embodiment of this invention. It is an image figure which shows an example of the audio image imaged with the water column observation apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Water column observation apparatus 2 Water buoy 3 Hoisting machine 4 Suspension cable 5 Acoustic imaging device 6 Elevator controller 7 Transmission cable 8 Wireless transmission device 9 Physical quantity sensor group 10 Gimbal

Claims (4)

A water buoy, a hoist mounted on the water buoy, a suspension rope suspended from the hoist, and a periphery attached to the suspension rope while rotating around a vertical rotation axis and audio-visual image acquisition device for capturing an audiovisual, a lifting controller for imaging and audio-visual bubble groups water column by vertically moving the acoustic image pickup device by controlling the hoisting machine in the water depth interval And a transmission cable for transmitting audio / video electronic information from the audio / video imaging device to the water buoy, and a wireless transmission device mounted on the water buoy for wirelessly transmitting the audio / video electronic information. Water column observation device.   2. The water column observation apparatus according to claim 1, wherein the acoustic image pickup device is attached to the suspension cable via a gimbal so that the posture is maintained in a vertical direction. Attach an acoustic image pickup device that picks up the surrounding sound image while rotating around the vertical axis of rotation to the suspension rope suspended from the hoist mounted on the water buoy. by vertically moving the acoustic image pickup device in a water depth interval imaging and audio-visual bubble groups water column around the depth interval of said audio visual imaging equipment, audio-visual electronic information from the acoustic image pickup device A water column observation method characterized in that the water is transmitted by a transmission cable and a wireless transmission device .   The water column observation method according to claim 3, wherein an acoustic image of a bubble group is extracted from the acoustic image, and a leaked gas amount is estimated from scale information and scattering intensity of the bubble group acoustic image.

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