CN213813975U - Distributed optical fiber sensing-based ocean bottom seismic data acquisition system - Google Patents
Distributed optical fiber sensing-based ocean bottom seismic data acquisition system Download PDFInfo
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Abstract
The utility model provides a submarine seismic data acquisition system based on distributed optical fiber sensing, an air gun seismic source excitation ship is provided with a plurality of towed air gun seismic sources; a plurality of boxes are distributed on the data acquisition armored optical cable at equal intervals, a surrounding optical fiber ring is arranged in each box, and an optical fiber attitude sensor is arranged at the top of each box; the distributed optical fiber acoustic wave sensing modulation and demodulation instrument is arranged in a buoy on the sea surface, is connected to one end or two ends of the data acquisition armored optical cable and is used for receiving optical fiber earthquake signals and optical fiber attitude sensors which are distributed along the data acquisition armored optical cable. The utility model discloses by a wide margin reduction ocean bottom seismic data acquisition system's production manufacturing cost, the use and the maintenance of being convenient for in marine production moreover can be longer than conventional active ocean bottom seismic data acquisition cable, can have more seismic sensor of quantity on every cable, can the more efficient collection high density ocean bottom seismic data.
Description
Technical Field
The utility model belongs to use geophysical exploration method relates to the marine seismic exploration technique, specifically is a seabed seismic data acquisition system based on distributed optical fiber sensing.
Background
The current ocean bottom seismic data acquisition modes mainly comprise two modes, wherein one mode is that a single-component, two-component, three-component or four-component ocean bottom seismic data acquisition cable (OBC) sinks into the ocean bottom to acquire seismic data, the other mode is that an independent three-component or four-component ocean bottom seismic data acquisition station (OBS and OBN) sinks to acquire seismic data, and the two modes are both excited by using an independent ocean seismic air gun excitation source when the ocean seismic air gun excitation source is dragged in water. The submarine seismic data acquisition cable sunk into the sea bottom works in a mode that a submarine seismic cable (OBC) is firstly released and distributed to the sea bottom by a cable releasing ship, then an underwater controllable air gun seismic source is dragged by an air gun seismic source ship to move forwards at a certain depth below the sea surface and excite seismic signals into the sea water, and the submarine seismic data are acquired by the seismic cable which is released and distributed to the sea bottom in advance. After the data acquisition is finished, the cable laying vessel recovers the submarine seismic cable, releases the submarine seismic cable to a new measurement work area, and repeats the data acquisition operation of submarine seismic signals. Independent ocean bottom seismic data acquisition cables and ocean bottom seismic data acquisition stations such as various OBC, OBS and OBN manufactured and sold by the companies ION, Sercel, Fairfield and OYOGeospace, etc.
At present, all used and published sunk marine seismic data acquisition stations adopt a counterweight cement block to bring the marine seismic data acquisition station to the sea bottom, after data acquisition is finished, an ultra-short base line (USBL) acoustic control unit arranged at the bottom of a ship sends a control signal to the seismic data acquisition station at the sea bottom, an acoustic or mechanical release device of the marine seismic data acquisition station is started, the marine seismic data acquisition station is separated from the counterweight cement block, and the acquisition station is brought to the sea surface by a glass floating ball at the upper part of the marine seismic data acquisition station and then recovered. The bottom-sinking type acquisition station has large volume, high cost and heavy weight, and a large number of high-density two-dimensional seabed seismic data acquisition measuring lines or three-dimensional measuring networks cannot be arranged on the seabed. In addition, the acquisition station sinks freely when being put in, the fixed-point putting precision control is not realized, the submarine earthquake acquisition station is brought to the sea surface by the glass floating ball when being recovered, the construction efficiency is low, and the submarine earthquake acquisition station cannot be separated from the balance weight cement block due to the failure of the acoustic or mechanical release device, so that the submarine earthquake acquisition station is lost due to the recovery failure.
A plurality of four-component submarine seismic signal acquisition units are distributed on an existing conventional submarine seismic data acquisition cable (OBC) at equal intervals along the cable, so that the conventional submarine seismic data acquisition cable is extremely heavy and can only be used in sea areas with the operating water depth not more than 500 m. In addition, due to the limited data transmission capability of the submarine cable, all submarine seismic data acquired by the overlong acquisition cable cannot be transmitted to a buoy on the sea surface or a seismic data acquisition computer on an air gun seismic source excitation ship in real time.
SUMMERY OF THE UTILITY MODEL
The utility model discloses aim at provides a seabed seismic data acquisition system based on distributed optic fibre acoustic wave sensing (DAS) to carry out deep sea seabed seismic data acquisition work.
The utility model discloses a following mode realizes:
the submarine seismic data acquisition system based on distributed optical fiber acoustic wave sensing comprises an air gun seismic source excitation ship, a data acquisition armored optical cable and a distributed optical fiber acoustic wave sensing modulation and demodulation instrument, wherein the data acquisition armored optical cable is distributed to the seabed;
the air gun seismic source excitation ship is provided with a plurality of towed air gun seismic sources;
a plurality of boxes are distributed on the data acquisition armored optical cable at equal intervals, a surrounding optical fiber ring is arranged in each box, and an optical fiber attitude sensor is arranged at the top of each box;
the distributed optical fiber acoustic wave sensing modulation and demodulation instrument is arranged in a buoy on the sea surface, is connected to one end or two ends of the data acquisition armored optical cable and is used for receiving optical fiber earthquake signals and optical fiber attitude sensors which are distributed along the data acquisition armored optical cable.
The surrounding optical fiber ring is formed by uniformly winding single-mode optical fibers in the data acquisition armored optical cable for 5 to 10 circles in a clockwise direction or an anticlockwise direction, and the diameter of the surrounding optical fiber ring is 0.1 to 0.2 meters.
Further, adjacent surrounding fiber rings are equally spaced, with a spacing of 6.25 meters, 12.5 meters, 25 meters, or 50 meters.
The optical fiber attitude sensor is an optical fiber gyroscope and is used for measuring the attitude of a surrounding optical fiber ring in a corresponding box, recording the inclination angle, the azimuth angle and the inclination of the surrounding optical fiber ring in real time and performing necessary rotation processing on the recorded submarine seismic data.
The buoy also comprises a diesel generator which continuously supplies power to the distributed optical fiber acoustic wave sensing modulation and demodulation instrument through a cable; and the top of the buoy is provided with an antenna for transmitting and receiving wireless signals, and the antenna is used for receiving GPS signals and wirelessly transmitting acquired ocean bottom seismic data to an air gun seismic source excitation ship in real time.
The utility model also provides a seabed seismic data acquisition method based on distributed optical fiber sound wave sensing adopts the above-mentioned seabed seismic data acquisition system based on distributed optical fiber sound wave sensing, including following step:
(a) a source excitation ship of the recovery air gun is laid by using armored optical cables to lay a plurality of data acquisition armored optical cables to the seabed of the seabed seismic data acquisition area according to the construction design requirement;
(b) connecting a buoy at one end or two ends of the data acquisition armored optical cable, starting a diesel generator in the buoy to continuously supply power to the distributed optical fiber sound wave sensing modulation and demodulation instrument, starting the distributed optical fiber sound wave sensing modulation and demodulation instrument to perform self-check on the state of the data acquisition armored optical cable, and after the data acquisition armored optical cable, the surrounding optical fiber ring and the optical fiber attitude sensor are ensured to work normally, the distributed optical fiber sound wave sensing modulation and demodulation instrument enters a standby state to prepare for acquiring submarine seismic data;
(c) the method comprises the following steps that an air gun seismic source excitation ship moves to a pre-designed seismic source line starting end, then the air gun seismic source is dragged to move at a constant speed along a seismic source line at a certain depth below the sea level, the excitation of the air gun seismic source is carried out at each seismic source point, an excitation starting signal of the air gun seismic source is synchronously sent to an antenna, and a distributed optical fiber acoustic wave sensing modulation and demodulation instrument is started to acquire seabed seismic data according to a pre-set acquisition requirement;
(d) the distributed optical fiber acoustic wave sensing modulation and demodulation instrument automatically demodulates the collected phase signals of Rayleigh scattering light reflected from each point along the data collection armored optical cable into seismic wave signals of each measuring point, and stores the seismic wave signals in a data hard disk;
(e) transmitting the acquired submarine seismic data to an air gun seismic source excitation ship in real time by using an antenna for quality monitoring or on-site rapid processing or on-site rapid stacking section imaging;
(f) after the pre-designed seismic source points in all the data acquisition armored optical cable arrangement blocks are excited, the arrangement and recovery air gun seismic source excitation ship of the data acquisition armored optical cables recovers the data acquisition armored optical cables into a winch on the air gun seismic source excitation ship one by one; after all the data acquisition armored optical cables distributed on the seabed are recovered, the arrangement and recovery air gun seismic source excitation ship of the data acquisition armored optical cables moves to the next seabed seismic data acquisition work area, and the data acquisition armored optical cables are distributed to the seabed one by one according to a construction design scheme;
(g) after the data acquisition armored optical cable is laid, the air gun seismic source excitation ship moves to the starting end of the designed seismic source line, the air gun seismic source is dragged to start to excite the air gun seismic source point by point along the seismic source line in a certain depth below the sea level, and meanwhile, the distributed optical fiber acoustic wave sensing modulation and demodulation instrument is started to acquire seabed seismic data excited by the air gun seismic source by emitting excitation synchronous signals to the antenna.
The utility model discloses can simplify seabed seismic data acquisition system's design and manufacturing at to a great extent. Because the optical fiber submarine seismic data acquisition cable is not provided with any electronic device and general seismic signal sensor, the production and manufacturing cost of the submarine seismic data acquisition system is greatly reduced, and the use and maintenance in offshore production are facilitated. Because the utility model provides a submarine fiber seismic data acquisition cable is passive form seismic data acquisition system, can do longer than conventional active submarine seismic data acquisition cable, can have the seismic sensor more that more intensive and quantity on every cable, can the more efficient collection high density submarine seismic data. In addition, the submarine seismic data acquisition optical cable can improve the submarine seismic data acquisition amount of one-time construction by multiple times, effectively improve the target detection precision, and realize the exploration and evaluation of marine mineral products, oil and gas resources and methane (natural gas) hydrates by applying a submarine seismic exploration technology.
Drawings
FIG. 1 is a schematic representation of a submarine fiber optic seismic data acquisition cable with a surrounding fiber optic ring deployed subsea.
FIG. 2 is a schematic representation of an undersea fiber optic seismic data acquisition cable deployed undersea without a surrounding fiber optic ring.
FIG. 3 is a schematic diagram of a looped fiber optic ring and fiber optic attitude sensor connection.
Fig. 4 is a schematic view of a buoy structure for connecting one end of an armored cable.
Detailed Description
To facilitate understanding of the technical contents of the present invention by those skilled in the art, the present invention will be further explained with reference to the accompanying drawings.
As shown in fig. 1 and fig. 2, the submarine seismic data acquisition system based on distributed optical fiber acoustic wave sensing comprises an air gun seismic source excitation ship 8, a data acquisition armored optical cable 3 arranged to the seabed, and a distributed optical fiber acoustic wave sensing modulation and demodulation instrument 10;
the air gun seismic source excitation ship 8 is provided with a plurality of towed air gun seismic sources 9;
a plurality of cylindrical high-pressure resistant boxes 13 are distributed on the data acquisition armored optical cable 3 at equal intervals, as shown in fig. 3, a surrounding optical fiber ring 4 is arranged in each box 13, and an optical fiber attitude sensor 7 is arranged at the top of each box 13;
as shown in fig. 4, the distributed optical fiber acoustic wave sensing modem apparatus 10 is disposed in a buoy 6 at the sea surface, and the distributed optical fiber acoustic wave sensing modem apparatus 10 is connected to one end or both ends of the data acquisition armored cable 3 and is configured to receive optical fiber seismic signals and optical fiber attitude sensors 7 distributed along the data acquisition armored cable 3.
The distributed optical fiber acoustic wave sensing modulation and demodulation instrument 10 can be connected with one end of the data acquisition armored optical cable 3 and can also be connected with two ends of the data acquisition armored optical cable 3. When the two ends of the armored optical cable 3 are connected with the distributed optical fiber acoustic wave sensing modulation and demodulation instrument 10, the length of the data acquisition armored optical cable 3 can be doubled, and the data acquisition efficiency is improved.
The surrounding optical fiber ring 4 uniformly winds the single-mode optical fiber in the data acquisition armored optical cable 3 for 5 to 10 circles in a clockwise direction or an anticlockwise direction, and the diameter of the surrounding optical fiber ring 4 is 0.1 to 0.2 meters.
Adjacent surrounding fibre rings 4 are equally spaced, with a spacing of 6.25, 12.5, 25 or 50 metres.
The optical fiber attitude sensor 7 is an optical fiber gyroscope and is used for measuring the attitude of the surrounding optical fiber ring 4 in the corresponding box 13, recording the inclination angle, the azimuth angle and the inclination of the surrounding optical fiber ring 4 in real time and performing necessary rotation processing on the recorded ocean bottom seismic data.
The buoy 6 also comprises a diesel generator 11, and the diesel generator 11 continuously supplies power to the distributed optical fiber acoustic wave sensing modulation and demodulation instrument 10 through a cable; and an antenna 12 for transmitting and receiving wireless signals is arranged at the top of the buoy 6 and is used for receiving GPS signals and wirelessly transmitting acquired ocean bottom seismic data to the air gun seismic source excitation ship 8 in real time.
The ocean bottom seismic data acquisition method based on the distributed optical fiber acoustic wave sensing comprises the following steps:
(a) a source excitation ship of the recovery air gun is laid by using armored optical cables to lay a plurality of data acquisition armored optical cables 3 to the seabed of the seabed seismic data acquisition area according to the construction design requirement;
(b) connecting a buoy 6 at one end or two ends of the data acquisition armored optical cable 3, starting a diesel generator 11 in the buoy 6 to continuously supply power to a distributed optical fiber sound wave sensing modulation and demodulation instrument 10, starting the distributed optical fiber sound wave sensing modulation and demodulation instrument 10 to perform self-checking on the state of the data acquisition armored optical cable 3, and after the data acquisition armored optical cable 3, the surrounding optical fiber ring 4 and the optical fiber attitude sensor 7 work normally, enabling the distributed optical fiber sound wave sensing modulation and demodulation instrument 10 to enter a standby state to prepare for acquiring submarine seismic data;
(c) the air gun seismic source excitation ship 8 moves to the starting end of a pre-designed seismic source line, then drags the air gun seismic source 9 to move at a constant speed along the seismic source line at a certain depth below the sea level and excites the air gun seismic source 9 at each seismic source point, synchronously sends an excitation starting signal of the air gun seismic source 9 to the antenna 12, and starts the distributed optical fiber acoustic wave sensing modulation and demodulation instrument 10 to acquire seabed seismic data according to the pre-set acquisition requirement;
(d) the distributed optical fiber acoustic wave sensing modulation and demodulation instrument 10 automatically demodulates the collected phase signals of Rayleigh scattering light reflected from each point along the data collection armored optical cable 3 into seismic wave signals of each measuring point, and stores the seismic wave signals on a data hard disk;
(e) transmitting the acquired submarine seismic data to the air gun seismic source excitation ship 8 in real time by using the antenna 12 for quality monitoring or on-site rapid processing or on-site rapid stacking section imaging;
(f) after the pre-designed seismic source points in the distribution blocks of all the data acquisition armored optical cables 3 are excited, the distribution recovery air gun seismic source excitation ship of the data acquisition armored optical cables 3 recovers the data acquisition armored optical cables 3 into a winch on the air gun seismic source excitation ship one by one; after all the data acquisition armored optical cables 3 arranged on the seabed are recovered, the arrangement recovery air gun seismic source excitation ship of the data acquisition armored optical cables 3 moves to the next seabed seismic data acquisition work area, and the data acquisition armored optical cables 3 are arranged to the seabed one by one according to a construction design scheme;
(g) after the data acquisition armored optical cable 3 is laid, the air gun seismic source excitation ship 8 moves to the starting end of the designed seismic source line, the air gun seismic source 9 is dragged to start to excite the air gun seismic source 9 point by point along the seismic source line in a certain depth below the sea level, and meanwhile, the distributed optical fiber acoustic wave sensing modulation and demodulation instrument 10 is started to acquire seabed seismic data excited by the air gun seismic source 9 by emitting excitation synchronous signals to the antenna 12.
The utility model discloses can simplify seabed seismic data acquisition system's design and manufacturing at to a great extent. Because the optical fiber submarine seismic data acquisition cable is not provided with any electronic device and general seismic signal sensor, the production and manufacturing cost of the submarine seismic data acquisition system is greatly reduced, and the use and maintenance in offshore production are facilitated. Because the utility model provides a submarine fiber seismic data acquisition cable is passive form seismic data acquisition system, can do longer than conventional active submarine seismic data acquisition cable, can have the seismic sensor more that more intensive and quantity on every cable, can the more efficient collection high density submarine seismic data. In addition, the submarine seismic data acquisition optical cable can improve the submarine seismic data acquisition amount of one-time construction by multiple times, effectively improve the target detection precision, and realize the exploration and evaluation of marine mineral products, oil and gas resources and methane (natural gas) hydrates by applying a submarine seismic exploration technology.
Claims (5)
1. The distributed optical fiber sensing-based seabed seismic data acquisition system is characterized by comprising an air gun seismic source excitation ship (8), a data acquisition armored optical cable (3) distributed to the seabed and a distributed optical fiber acoustic wave sensing modulation and demodulation instrument (10);
the air gun seismic source excitation ship (8) is provided with a plurality of towed air gun seismic sources (9);
a plurality of boxes (13) are distributed on the data acquisition armored optical cable (3) at equal intervals, a surrounding optical fiber ring (4) is arranged in each box (13), and an optical fiber attitude sensor (7) is arranged at the top of each box (13);
the distributed optical fiber acoustic wave sensing modulation and demodulation instrument (10) is arranged in a buoy (6) on the sea surface, and the distributed optical fiber acoustic wave sensing modulation and demodulation instrument (10) is connected to one end or two ends of the data acquisition armored optical cable (3) and used for receiving optical fiber earthquake signals and optical fiber attitude sensors (7) signals distributed along the data acquisition armored optical cable (3).
2. The distributed fiber sensing-based ocean bottom seismic data acquisition system according to claim 1, wherein the surrounding fiber ring (4) uniformly winds the single-mode fiber in the data acquisition armored cable (3) for 5 to 10 circles in a clockwise or counterclockwise direction, and the diameter of the surrounding fiber ring (4) is between 0.1 and 0.2 meters.
3. Ocean bottom seismic data acquisition system based on distributed fiber sensing according to claim 1 or 2, wherein adjacent surrounding fiber rings (4) are equally spaced with a spacing of 6.25 meters, 12.5 meters, 25 meters or 50 meters.
4. The distributed fiber sensing-based ocean bottom seismic data acquisition system according to claim 1, wherein the fiber optic attitude sensor (7) is a fiber optic gyroscope for measuring the attitude of the surrounding fiber optic ring (4) in the corresponding box (13), recording the inclination, azimuth and inclination of the surrounding fiber optic ring (4) in real time, and performing necessary rotation processing on the recorded ocean bottom seismic data.
5. The distributed optical fiber sensing-based ocean bottom seismic data acquisition system according to claim 1, wherein the buoy (6) further comprises a diesel generator (11), and the diesel generator (11) continuously supplies power to the distributed optical fiber acoustic wave sensing modulation and demodulation instrument (10) through a cable; an antenna (12) for transmitting and receiving wireless signals is arranged at the top of the buoy (6) and is used for receiving GPS signals and wirelessly transmitting acquired ocean bottom seismic data to the air gun seismic source excitation ship (8) in real time.
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