CN213689961U - Ocean four-component optical fiber seismic data acquisition cable based on unmanned ship - Google Patents

Abstract

The utility model provides an ocean four-component optical fiber seismic data acquisition cable based on unmanned ship, which comprises a plurality of parallel acquisition towlines, wherein each acquisition towline comprises a plurality of acquisition short sections which are connected in series at equal intervals through armored optical cables; the head end and the tail end of each acquisition streamer are respectively towed by unmanned boats or sunk to the seabed; the armored optical cable is connected with a modulation and demodulation instrument on the unmanned boat or the buoy; and a GPS or Beidou chip in the modulation and demodulation instrument carries out time synchronization with the marine air gun vibration source controller through a satellite time service signal. The utility model discloses a three-component optical fiber vector sensor and optic fibre hydrophone, the frequency band scope is greater than conventional marine seismic signal's frequency band response far away, and sensitivity is high, and the structure is very simple, makes the utility model discloses a marine array quartering volume optic fibre seismic data gathers nipple joint can be used for the towline under water and gathers high-quality marine quartering volume seismic data.

Description

Ocean four-component optical fiber seismic data acquisition cable based on unmanned ship

Technical Field

The utility model belongs to the technical field of ocean geophysical exploration, a ocean quartering volume optic fibre seismic data gathers cable based on unmanned ship is related to.

Background

At present, there are three main marine seismic data acquisition modes, one is that a single-component, two-component, three-component or four-component towed marine seismic data acquisition cable (Streamer) is towed at the tail of an acquisition operation ship, and the marine seismic data acquisition cables such as various seismic cables (streamers) produced and sold by the companies of ION, Sercel, OYO Geospace and the like. The other is the sinking of three-component or four-component ocean bottom seismic data acquisition cables (OBC) into the ocean bottom, and the other is the sinking of independent three-component or four-component ocean bottom seismic data acquisition stations (OBS and OBN), and the independent ocean seismic air gun excitation source is excited when dragging in water. The towed marine seismic data acquisition cable works in such a way that an acquisition operation ship tows the acquisition cable to move forward at a constant speed at a certain depth below the water surface, and a controllable seismic source (such as an air gun seismic source) towed by the acquisition operation ship or a controllable seismic source (such as an air gun seismic source) towed by another seismic source operation ship and the acquisition cable synchronously move at a certain depth below the water surface and are positioned and excited at fixed time. 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 laid on the sea bottom by a cable releasing operation ship, then an underwater controllable seismic source (such as an air gun seismic source) is dragged by the air gun seismic source operation ship to move forwards at a certain depth below the sea surface and excite a seismic signal into the sea water, and the submarine seismic data is acquired by the seismic cable which is released and laid on the sea bottom in advance. And after the data acquisition is finished, the cable laying operation ship recovers the submarine seismic cable, puts the submarine seismic cable into a new measurement work area, and repeats the acquisition operation of the submarine seismic data.

The most widely used in the industry today is the acquisition of four-component marine seismic data by conventional three-component geophones and piezoelectric crystal hydrophones. The three-component detector is a special detector used in multi-wave exploration. Unlike a single-component conventional geophone, each geophone incorporates three mutually perpendicular sensors to record the three components of the particle velocity vector for simultaneous recording of longitudinal, transverse, and converted waves. The signal voltage output by such detectors is related to the displacement velocity of their vibrations and is therefore referred to as a velocity detector. In order to record the vibration signals sensed by the detector, circuit modules for amplifying analog signals output by the detector, filtering, denoising, analog-to-digital conversion, data storage, data transmission and the like are further arranged in the detector array, so that marine seismic data acquired by the three-component detector array are transmitted to an acquisition control computer on the towing workboat for storage through an armored cable with the length of thousands of meters. It is also difficult and very limited to power numerous data acquisition subs from the deck on marine seismic data acquisition cables that are several kilometers or even tens of kilometers away from the towing vessel. In addition, ocean four-component seismic data acquired by a three-component geophone and hydrophone array at present are completely transmitted from a data acquisition cable to a towing operation ship by an armored cable, and due to the limitation of long-distance (thousands to tens of kilometers) cable data transmission, high-speed real-time transmission of a large amount of data to the towing operation ship cannot be realized. The factors greatly limit the development and popularization and application of the large-channel or ultra-large-channel and large-length or ultra-large-length marine quartering geophone array (or quartering seismic data acquisition cable) technology.

In order to improve the efficiency of marine seismic data acquisition and increase the depth of investigation, conventional streamers are increasingly longer (increasing offset), and more streamers, some more than 20 to 30 streamers, are towed simultaneously by each acquisition vessel, and each streamer is also more than 10 kilometers in length. The field operation of a plurality of ultra-long seismic streamers is very difficult, tens of seismic data acquisition streamers which are towed in parallel behind an acquisition vessel are difficult to avoid being twisted together under the influence of ocean currents, and particularly when the tail ends of the streamers have no power buoy, the tail ends of the streamers beyond 10 kilometers are more easily twisted together under the influence of lateral ocean currents, so that serious production accidents are caused.

SUMMERY OF THE UTILITY MODEL

In order to solve the difficult problem of the limited bottleneck of long distance cable data transmission ability of the marine seismic data acquisition cable that conventional three-component wave detector pressurization electro-hydrophone constitutes, keep away from and pull the power supply problem of numerous data acquisition nipple joint on the marine seismic data acquisition cable of several kilometers or tens kilometers even to and be difficult to prevent the tail end winding of towline when tens of overlength seismic data acquisition towline operations from taking place the risk of potential production accident together, the utility model aims to provide an use unmanned ship to pull marine four components optic fibre seismic data acquisition cable based on unmanned ship specially to carry out marine multicomponent earthquake's data acquisition work, can measure the four components marine seismic data under the sea surface or seabed. The towed or bottom sinking array type marine four-component optical fiber seismic data acquisition optical fiber cable consists of three-component optical fiber vector sensors, optical fiber sound pressure hydrophones and optical fiber attitude sensors which are arranged in an armored optical cable and are uniformly distributed.

In order to solve the technical problem, the utility model provides a one of them technical scheme is:

the marine four-component optical fiber seismic data acquisition cable based on the unmanned ship comprises a plurality of parallel acquisition towlines, wherein each acquisition towline comprises a plurality of acquisition short sections which are connected in series at equal intervals through armored optical cables; the head end and the tail end of each acquisition towrope are respectively towed by unmanned boats; the armored optical cable is connected with a modulation and demodulation instrument on the unmanned ship; and a GPS or Beidou chip in the modulation and demodulation instrument carries out time synchronization with the marine air gun vibration source controller through a satellite time service signal.

Each acquisition short section comprises a three-component optical fiber vector sensor, an optical fiber sound pressure hydrophone and a three-component optical fiber attitude sensor.

The three-component optical fiber vector sensor is arranged at the front part of the acquisition short section, and the three-component optical fiber attitude sensor and the optical fiber sound pressure hydrophone are arranged behind the three-component optical fiber vector sensor in sequence; the three-component optical fiber vector sensor, the optical fiber sound pressure hydrophone and the three-component optical fiber attitude sensor are connected with a modulation and demodulation instrument.

The three-component optical fiber vector sensor is a three-component seismic signal detector. The three-component optical fiber vector sensor detects acceleration vectors in an underwater sound field, and the basic structure of the three-component optical fiber vector sensor is based on acceleration detection. The vector sensor adopts a mandrel type structure in an optical fiber acceleration sensor as a basic structure of the sensor.

The fiber vector sensor adopts a push-pull structure, the resonant frequency is larger, and the working bandwidth is wider. More importantly, the push-pull structure has good symmetry and can obtain good vectorial property.

In the actual detection of the underwater sound field, the three-component optical fiber vector sensor is formed by packaging a sensing core module in a cylinder, a spherical shell or a square shell. The wave size of the three-component vector sensor is small, the mass of the three-component vector sensor is almost equal to the mass of water drained by the three-component vector sensor, and therefore the three-component vector sensor is equivalent to a particle in an underwater sound field and does not influence the distribution and the propagation of the sound field. In an underwater sound field, the acceleration motion of a particle is caused by the wave motion of sound waves, so that the components of the acceleration vector of the sound field in the axial direction of each dimension are obtained by each dimension of the three-component vector sensor. The vector detection system comprises a three-component vector sensor, an optical fiber sound pressure hydrophone, a three-component optical fiber attitude sensor and a modulation and demodulation instrument comprising a dry end light source.

The three-component optical fiber vector sensor comprises three solid elastic cylinders with the same geometric dimension which are assembled together in a triaxial orthogonal structure, a pair of optical fibers are respectively wound on two end arms of one elastic cylinder, and the wound optical fibers form two optical fiber arms of a Michelson interferometer; the mass block is bonded at the orthogonal joint of the elastic cylinder body, and the elastic cylinder body is fixedly arranged in the sealed shell; the optical fiber is connected with a modulation and demodulation instrument.

The optical fiber acoustic pressure hydrophone is selected from an amplitude modulation type optical fiber hydrophone, a phase modulation type optical fiber hydrophone or a polarization type optical fiber hydrophone. The three-component optical fiber attitude sensor is an optical fiber gyroscope.

The spacing between the acquisition short sections is selected from any one of 3.125 meters, 6.25 meters, 12.5 meters or 25 meters.

The data acquisition method of the marine four-component optical fiber seismic data acquisition cable based on the unmanned ship comprises the following steps:

a. the head and the tail of each acquisition towline are respectively towed and towed by two unmanned boats, or a plurality of acquisition towlines are parallelly arranged on the sea surface of a marine seismic data acquisition work area by a plurality of pairs of unmanned boats according to a pre-designed interval, or a plurality of acquisition towlines are parallelly sunk to the seabed of the seabed seismic data acquisition work area according to a pre-designed interval, and a modulation and demodulation instrument on the unmanned boat starts the acquisition towlines through armored optical cables to carry out instrument state self-checking, so that each acquisition short section on each acquisition towline can work normally;

b. the seismic source ship used for marine seismic data acquisition tows one or more controllable air gun seismic source guns to be sequentially excited through a marine air gun seismic source controller point by point according to a seismic source line designed by construction, and an acquisition streamer towed behind an unmanned ship or an acquisition streamer sunk at the sea bottom synchronously acquires full-wave-field four-component marine seismic data excited by a sea surface controllable air gun seismic source according to an offset distance designed by construction, namely the distance between a seismic source point and a receiving point;

c. the three-component optical fiber attitude sensor which is arranged next to the three-component optical fiber vector sensor synchronously acquires the three-component attitude data of each acquisition short section at the data acquisition position in real time and records the inclination angle, azimuth angle and inclination of each three-component optical fiber vector sensor in real time so as to be used for carrying out necessary rotation processing on the recorded four-component marine seismic data;

d. the acquisition towline transmits the four-component marine seismic data acquired in the step b, the three-component attitude data of the acquisition short section at the data acquisition position acquired in the step c to a modulation and demodulation instrument on the unmanned ship through an armored optical cable, and then the three-component attitude data is converted into marine four-component seismic data at corresponding positions through modulation and demodulation;

e. according to three-component attitude data of each acquisition short section at a data acquisition position synchronously acquired in real time by a three-component optical fiber attitude sensor, converting marine four-component seismic data of a corresponding acquisition position in the step d into three-component marine seismic data of the corresponding acquisition position through rotating projection to obtain three-component marine seismic data of the position along the vertical direction and two orthogonal horizontal directions parallel to the sea level, wherein one horizontal component is a horizontal component along the extension direction of the acquisition towline, and the other horizontal component is a horizontal component vertical to the extension direction of the acquisition towline;

f. and d, carrying out marine seismic data processing on the marine quartering seismic data converted into the corresponding data acquisition positions in the step e, wherein the marine seismic data processing comprises but is not limited to: shaping seismic wavelets, removing complex multiples, recovering reliable effective reflected waves from data with low signal-to-noise ratio, using seismic source signal deconvolution to realize the shaping of seismic records, improving the signal-to-noise ratio of the effective reflected waves, speed modeling, stratigraphic division, tomography, high-frequency recovery, ghost wave removal, multiple wave elimination, deconvolution processing, anisotropic time domain or depth domain migration imaging, Q compensation or Q migration, and finally obtaining the longitudinal and transverse wave speed, the longitudinal and transverse wave impedance, the longitudinal and transverse wave anisotropy coefficient, the longitudinal and transverse wave attenuation coefficient, the elastic parameter, the viscoelastic parameter, seismic attribute data and the geological high-resolution structural imaging below the seabed of the medium below the seabed, the method is used for investigation and exploration of mineral resources under the seabed, and realizes high-resolution geological structure imaging of the geological mineral resources and oil and gas reservoirs under the seabed and comprehensive evaluation of the oil and gas-containing reservoirs.

The three-component optical fiber vector sensor and the optical fiber sound pressure hydrophone have the advantages of high sensitivity, wide frequency band, good high-frequency response, no need of power supply, corrosion resistance and high pressure resistance. The difficult problem of power supply to a plurality of data acquisition short sections on the marine seismic data acquisition towing cable which is far away from the towed unmanned ship by kilometers or even dozens of kilometers is solved. In addition, the three-component optical fiber vector sensor has higher sensitivity, wider frequency band and better high-frequency response characteristic than a conventional three-component detector, and can realize multi-channel high-speed transmission with large data volume. And because the front end of the sensor is not provided with electronic elements, the sensor has higher reliability, high voltage resistance, no need of power supply, water resistance, corrosion resistance, capability of being laid on the seabed for a long time, electromagnetic interference resistance and small channel crosstalk.

The utility model has the advantages that: the utility model discloses an adopt high pressure resistant three-component optical fiber vector sensor in array ocean quartering volume optical fiber seismic data collection system, high pressure resistant optical fiber sound pressure hydrophone, high pressure resistant three-component optical fiber attitude sensor, realize big passageway or super large passageway, the massive seismic data of the collection of big length or super large length ocean quartering volume seismic data and the high density high frequency collection is from gathering the cable to the high-speed transmission who drags unmanned ship, the bottleneck problem of the massive data of having solved conventional array ocean quartering volume seismic data collection cable the inside to the high-speed transmission who drags the ship has eliminated from the deck for keeping away from the difficult problem of numerous data acquisition nipple joint power supply on the ocean seismic data collection cable of dragging the operation ship several kilometers or even tens of kilometers. Because the head end and the tail end of each ocean four-component optical fiber seismic data acquisition cable based on the unmanned ship are connected with the unmanned ship, the tail ends of a plurality of overlength ocean seismic data acquisition cables can be conveniently prevented from being interfered by ocean currents during operation and being wound together to form potential production accidents through override of the unmanned ship.

Drawings

FIG. 1 is a schematic diagram showing a basic structure of a three-dimensional spindle-type push-pull sensor head according to an embodiment;

FIG. 2 is a schematic diagram of a vector sensor and an acoustic hydrophone photoelectric signal processing system of the present embodiment;

FIG. 3 is a schematic diagram of operational layout of a towed marine four-component fiber seismic data acquisition system (Streamer) according to the embodiment;

fig. 4 is a schematic diagram of the operational deployment of the ocean bottom four-component fiber optic seismic data acquisition system (OBC) of the present embodiment.

Detailed Description

In order to facilitate understanding of the present invention, the present invention will be described in more detail with reference to the accompanying drawings and specific embodiments. Preferred embodiments of the present invention are shown in the drawings. The invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

The utility model discloses an unmanned ship based marine four-component optical fiber seismic data acquisition cable, which comprises a plurality of acquisition towropes 1, wherein the acquisition towropes 1 are formed by connecting a plurality of acquisition short sections 3 in series at equal intervals; each acquisition short section 3 comprises a three-component optical fiber vector sensor 4, an optical fiber sound pressure hydrophone 5 and a three-component optical fiber attitude sensor 6, and the three-component optical fiber attitude sensor 6 is an optical fiber gyroscope.

The three-component optical fiber vector sensor 4 is arranged at the front part of the acquisition short section 3, and the three-component optical fiber attitude sensor 6 and the optical fiber sound pressure hydrophone 5 are arranged behind the three-component optical fiber vector sensor.

The optical fiber acoustic hydrophone 5 is selected from an amplitude modulation type optical fiber hydrophone, a phase modulation type optical fiber hydrophone or a polarization type optical fiber hydrophone.

As shown in fig. 1, the three-component optical fiber vector sensor 4 is a three-component seismic signal detector, the three-component optical fiber vector sensor 4 detects an acceleration vector in an underwater acoustic field, and the basic structure is a structure based on acceleration detection. The three-component optical fiber vector sensor 4 adopts a mandrel type structure in an optical fiber acceleration sensor as a basic sensor structure.

The three-component optical fiber vector sensor 4 adopts a push-pull structure, and has a larger resonance frequency and a wider working bandwidth. More importantly, the push-pull structure has good symmetry and can obtain good vectorial property.

The three-component optical fiber vector sensor 4 comprises three solid elastic cylinders 41 with the same geometric dimension which are assembled together in a triaxial orthogonal structure, a pair of optical fibers 42 are respectively wound on two end arms of one elastic cylinder 41, and the wound optical fibers 42 form two optical fiber arms of a Michelson interferometer; the mass block is bonded at the orthogonal joint of the elastic column body 41, and the elastic column body 41 is fixedly arranged in the sealed shell; the optical fiber 42 is connected to the modem apparatus 7. The three-component optical fiber vector sensor 4 comprises three solid elastic cylinders 41 with the same geometric dimension which are assembled together in a triaxial orthogonal structure, a pair of optical fibers 42 are respectively wound on two end arms of one elastic cylinder 41, and the wound optical fibers 42 form two optical fiber arms of a Michelson interferometer; the mass block is bonded at the orthogonal joint of the elastic column body 41, and the elastic column body 41 is fixedly arranged in the sealed shell; the optical fiber 42 is connected to the modem apparatus 7. In the actual detection of the underwater sound field, the three-component optical fiber vector sensor 4 encapsulates the sensing core module in a cylinder, a spherical shell or a square shell to form the three-component optical fiber vector sensor 4. The wave size of the three-component vector sensor 4 is small, and the mass of the three-component vector sensor is almost equal to the mass of water drained by the three-component vector sensor, so that the three-component vector sensor is equivalent to a particle in an underwater sound field and does not influence the distribution and the propagation of the sound field. In an underwater sound field, the acceleration motion of a particle is caused by the wave motion of sound waves, so that the components of the acceleration vector of the sound field in the axial direction of each dimension are obtained by each dimension of the three-component vector sensor 4. The vector detection system comprises a three-component vector sensor 4, an optical fiber acoustic hydrophone 5, a three-component attitude sensor 6, a dry-end light source and a photoelectric signal processing system, namely a modulation and demodulation instrument 7.

As shown in fig. 2, the light source at the dry end is modulated by the optoelectronic signal processing module, and the emitted light is transmitted through an optical fiber, sent to the three-component optical fiber vector sensor 4 and the optical fiber sound pressure hydrophone 5, and returned to the optoelectronic signal processing end through the transmission optical fiber after being loaded with the sound pressure signal and the vibration velocity signal. The fiber optic acoustic hydrophone 5 must be exposed to seawater and the three-component vector sensor 4 must be suspended from a support using springs. The modulation and demodulation instrument 7 is installed in a watertight cabin on an unmanned ship 11 and is connected with the three-component optical fiber vector sensor 4, the optical fiber sound pressure hydrophone 5 and the three-component optical fiber attitude sensor 6 in the acquisition streamer 1 through optical fiber passing through the cabin.

The acquisition short sections 3 are connected through armored cables 2, and the distance is selected from any one of 3.125 meters, 6.25 meters, 12.5 meters or 25 meters.

Each acquisition streamer 1 is towed by two unmanned boats 11 at their fore and aft ends below the surface of the seawater. The streamer is connected to a modem instrument 7 on the unmanned vehicle 11 through an armored fiber optic cable 2. The plurality of acquisition streamers 1 are towed under the sea surface by a plurality of pairs of unmanned boats in parallel at equal intervals, or are sunk on the sea bottom in parallel, and the distance between the streamers is between several meters and tens of meters. And a GPS or Beidou chip in the modulation and demodulation instrument 7 carries out time synchronization with the marine air gun vibration source controller 9 through a satellite time service signal.

Adopt the utility model provides an array ocean quartering volume optic fibre seismic data collection system, the concrete step of gathering seismic data is as follows:

a. the head and the tail of each acquisition streamer 1 are respectively towed and towed by two unmanned boats 11, or a plurality of acquisition streamers 1 are parallelly arranged on the sea surface of a marine seismic data acquisition work area by a plurality of pairs of unmanned boats 11 according to a pre-designed interval, or a plurality of marine array type four-component optical fiber seismic data acquisition cables are parallelly sunk to the seabed of the seabed seismic data acquisition work area according to the pre-designed interval, a modulation and demodulation instrument 7 on the unmanned boats 11 starts the acquisition streamers 1 through armored optical cables 2 to carry out instrument state self-checking, and each acquisition pup joint 3 on each acquisition streamer 1 is ensured to work normally;

b. the seismic source ship 8 used for marine seismic data acquisition drags one or more controllable air gun seismic source guns 10 to sequentially excite point by point according to a seismic source line of a construction design, and drags an acquisition streamer 1 behind an unmanned ship 11 or sinks on a submarine acquisition streamer 1 to synchronously acquire full-wave field four-component marine seismic data excited by the sea surface controllable air gun seismic source guns 10 according to an offset distance (distance between a seismic source point and a receiving point) of the construction design;

c. the three-component optical fiber attitude sensor 6 (optical fiber gyroscope) which is arranged next to the three-component optical fiber vector sensor 4 synchronously collects the three-component attitude data of each acquisition short section 3 at the data acquisition position in real time and records the inclination angle, azimuth angle and inclination of each three-component optical fiber vector sensor 4 in real time so as to perform necessary rotation processing on the recorded four-component marine seismic data;

d. the acquisition streamer 1 transmits the four-component marine seismic data acquired in the step b and the three-component attitude data of the acquisition pup joint 3 acquired in the step c to a modem instrument 7 on the unmanned ship 11 through an armored optical cable 2, and then the three-component attitude data are converted into marine four-component seismic data of corresponding positions through modem;

e. according to the three-component attitude data of each acquisition short section 3 at the data acquisition position (below the sea surface or on the sea bottom) synchronously acquired in real time by the three-component optical fiber attitude sensor 6, converting the marine four-component seismic data at the corresponding acquisition position in the step d into three-component marine seismic data at the corresponding acquisition position through rotating projection to obtain three-component marine seismic data of the position along the vertical direction and two orthogonal horizontal directions parallel to the sea level, wherein one horizontal component is a horizontal component along the extension direction of the data acquisition cable 1, and the other horizontal component is a horizontal component perpendicular to the extension direction of the data acquisition cable 1;

f. and d, carrying out marine seismic data processing on the marine quartering seismic data converted into the corresponding data acquisition positions in the step e, wherein the marine seismic data processing comprises but is not limited to: shaping seismic wavelets, removing complex multiples (pressing or removing various multiples by combining a plurality of methods such as FK filtering, wave equation epitaxy method, deconvolution prediction and the like), recovering reliable effective reflected waves from data with low signal-to-noise ratio, realizing the shaping of seismic records by using the deconvolution of seismic source signals, improving the signal-to-noise ratio of the effective reflected waves, speed modeling, stratigraphic division, tomography imaging, high-frequency recovery, ghost wave removal, multiple wave elimination, deconvolution processing, anisotropic time domain or depth domain migration imaging, Q compensation or Q migration, finally obtaining the longitudinal and transverse wave speed, longitudinal and transverse wave impedance, longitudinal and transverse wave anisotropy coefficients, longitudinal and transverse wave attenuation coefficients, elastic parameters, viscoelastic parameters, seismic attribute data and sub-sea-bottom high-resolution geological structure imaging of a sub-sea-bottom medium, and being used for sub-sea-bottom geological structure investigation and mineral resource exploration, the high-resolution geological structure imaging of geological mineral resources and oil and gas reservoirs below the seabed and the comprehensive evaluation of oil and gas-containing reservoirs are realized.

As shown in fig. 3, the unmanned-vessel-based marine quarter fiber seismic data acquisition cable of the embodiment 1 includes a plurality of acquisition streamers 1, and each acquisition streamer 1 is formed by connecting a plurality of same acquisition pups 3 in series at equal intervals. As shown in fig. 2, each acquisition nipple 3 includes a three-component optical fiber vector sensor 4 installed inside the acquisition cable, the three-component optical fiber vector sensor 4 is installed at the front of the acquisition nipple 3, a three-component optical fiber attitude sensor 6 is installed next to the three-component optical fiber vector sensor 4, and an optical fiber sound pressure hydrophone 5 is arranged at the rear.

Each acquisition streamer 1 is towed by two unmanned boats 11 at their fore and aft ends below the surface of the seawater. The acquisition towline 1 is connected with a modulation and demodulation instrument on the unmanned ship through an armored optical cable 2. The plurality of acquisition towlines 1 are towed below the sea surface by a plurality of pairs of unmanned boats in parallel at equal intervals, and the distance between the towlines is between several meters and tens of meters. And a GPS or Beidou chip in the modulation and demodulation instrument 7 carries out time synchronization with the marine air gun vibration source controller 9 through a satellite time service signal.

Adopt the utility model provides an acquisition towrope 1 constitutes towed ocean four-component optical fiber seismic data acquisition system (Streamer) jointly with controllable air gun focus 10, focus ship 8. A single or tens of acquisition streamers 1 may be towed below the water surface at the tail end of the unmanned boat 11, with the acquisition streamers 1 spread parallel across the sea surface, with the cable-to-cable distance between a few meters and tens of meters, as shown in fig. 3.

Example 2 several tens of the streamers 1 provided in example 1 were laid down on the ocean floor in a parallel arrangement with controllable air gun sources 10 at the sea surface to form an ocean floor four-component fiber optic seismic data acquisition system (OBC), as shown in fig. 4.

According to the construction design, the controllable air gun seismic source 10 is towed by a seismic source ship 8 to move forward along the direction vertical to the acquisition towrope 1 and is excited point by point along a seismic source line of the construction design, and the acquisition towrope 1 which is sunk at the sea bottom synchronously acquires the sea bottom four-component seismic data excited by the air gun seismic source in real time. The acquisition of the ocean bottom four-component seismic data is controlled by a modem 7 housed in a buoy at one end of the acquisition streamer 1.

Claims (7)

1. Ocean quartering weight optic fibre seismic data acquisition cable based on unmanned ship, its characterized in that: the device comprises a plurality of parallel acquisition towlines (1), wherein each acquisition towline (1) comprises a plurality of acquisition short sections (3) which are connected in series at equal intervals through armored optical cables (2); the head end and the tail end of each acquisition towing cable (1) are respectively towed by unmanned boats (11); the armored optical cable (2) is connected with a modulation and demodulation instrument (7); and a GPS or Beidou chip in the modulation and demodulation instrument (7) carries out time synchronization with the marine air gun vibration source controller (9) through a satellite time service signal.

2. The unmanned-craft-based marine quarter-component fiber optic seismic data acquisition cable according to claim 1, characterized in that each of said acquisition subs (3) comprises a three-component fiber optic vector sensor (4), a fiber optic acoustic hydrophone (5) and a three-component fiber optic attitude sensor (6).

3. The unmanned-boat-based marine four-component optical fiber seismic data acquisition cable according to claim 2, characterized in that the three-component optical fiber vector sensor (4) is installed at the front of the acquisition nipple (3), and the three-component optical fiber attitude sensor (6) and the optical fiber acoustic pressure hydrophone (5) are arranged behind the three-component optical fiber vector sensor; the three-component optical fiber vector sensor (4), the sound pressure hydrophone (5) and the three-component optical fiber attitude sensor (6) are connected with a modulation and demodulation instrument (7).

4. The unmanned, craft-based marine quarter component fiber optic seismic data acquisition cable of claim 2, characterized in that said three-component fiber optic vector sensor (4) is a three-component seismic signal geophone.

5. The unmanned-craft-based marine quarter-component fiber seismic data acquisition cable according to claim 4, characterized in that the three-component fiber vector sensor (4) comprises three solid elastic cylinders (41) with identical geometric dimensions assembled together in a triaxial orthogonal structure, a pair of optical fibers (42) are respectively wound on two end arms of one elastic cylinder (41), and the wound optical fibers (42) form two fiber arms of a Michelson interferometer; the mass block is bonded at the orthogonal joint of the elastic column body (41), and the elastic column body (41) is fixedly arranged in the sealed shell; the optical fiber (42) is connected to the modem device (7).

6. The unmanned-craft-based marine quarter component fiber optic seismic data acquisition cable of claim 2, wherein the fiber optic acoustic hydrophone (5) is selected from an amplitude-modulated fiber optic hydrophone, a phase-modulated fiber optic hydrophone, or a polarized fiber optic hydrophone.

7. The unmanned craft-based marine quarter fiber seismic data acquisition cable according to claim 1 or 2, wherein the spacing between acquisition nipples (3) is selected from any one of 3.125 meters, 6.25 meters, 12.5 meters or 25 meters.

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