WO2022257429A1 - Submarine optical fiber four-component seismic instrument system and data collection method thereof - Google Patents

Abstract

A submarine optical fiber four-component seismic instrument system and a data collection method thereof. Four-component node seismic instruments are connected, by means of a circular cable ring (2), in series on an armored photoelectric composite cable (3) at certain intervals; the armored photoelectric composite cable (3) is connected to a computer; an external near-field wireless transmission module (6), an external photoelectric conversion module (7) and an external wireless charging module (8) are arranged on a side face of each four-component node seismic instrument in a matching manner, and the modules are all fixed on the armored photoelectric composite cable (3) by means of a functional module sleeve (4); and the four-component node seismic instruments are connected to the computer by means of the external near-field wireless transmission modules (6), and perform communication and data transmission. The system has the characteristics of high sensitivity, wide frequency band, good high-frequency response, linear phase change, good technical parameter consistency, etc. Moreover, there is no electronic element at a front end, so that the system has a higher reliability, that is, the system has the advantages of resistance to high temperature and high voltage, no need of power supply, water resistance, corrosion resistance, capability of being arranged for a long time, electromagnetic interference resistance and small channel crosstalk.

Description

Submarine optical fiber four-component seismic instrument system and its data acquisition method technical field

The invention belongs to the technical field of geophysical exploration, and relates to a submarine optical fiber four-component seismic instrument system and a data acquisition method thereof.

Background technique

Marine seismic surveying is a method of conducting seismic surveys on the ocean using survey ships. The principles, instruments used, and data processing methods of marine seismic exploration are basically the same as those of land seismic exploration. Because a large amount of oil and natural gas are found in the continental shelf area, marine seismic exploration has a very broad prospect. Marine seismic prospecting is a survey method for artificial earthquakes in seawater, which has four characteristics: ① most of them use non-explosive sources; cable); ③Continuous record of navigation; ④The data is processed by computer, with high work efficiency. Due to the above characteristics, the production efficiency of marine seismic exploration is much higher than that of land seismic exploration, and it is more necessary to use digital electronic computers to process data. Some special interference waves are often encountered in marine seismic exploration, such as ringing tremors and reverberations, as well as bottom wave interference related to the seabed.

Submarine seismic exploration technology is a kind of marine seismic exploration technology, which also consists of seismic sources and acquisition instruments. Most submarine seismic exploration technologies use non-explosive sources (mainly air guns), which float close to the sea surface and are towed by a marine seismic survey ship; the acquisition instruments are placed on the seabed to receive the longitudinal and transverse wave signals emitted by the source and reflected by the bottom of the seabed. Since seawater cannot propagate shear waves, only when the geophone is placed on the seabed can shear waves and converted waves be received. It is characterized in that it is excited in the water, received in the water, excited, and the receiving conditions are uniform; it can carry out continuous observation without stopping the ship. The detector initially uses a piezoelectric detector, and now it is developed to be used in combination with a piezoelectric detector and a vibration velocity detector. Submarine seismic exploration technology can be divided into ocean bottom cable exploration technology (Ocean Bottom Cable, referred to as OBC) and submarine node seismograph exploration technology (Ocean Bottom Node, referred to as OBN). OBC technology is to connect hundreds of geophones to the submarine cable, and the special release boat will sink the acquisition cable to the seabed under the guidance of the locator (the submarine cable can be one or more), and one end of the submarine cable It is connected to a fixed instrument ship (the instrument ship must be anchored back and forth at sea to ensure that the hull does not turn and the ship position does not deviate), and the marine seismic survey ship collects seabed seismic data by firing shots around the sea surface according to the designed survey line.

There are two main methods of seabed seismic data acquisition at present, one is single-component, two-component, three-component or four-component submarine seismic data acquisition cable (OBC) sinking into the seabed to collect seismic data, and the other is independent three-component or four-component The component bottom seismic data acquisition stations (OBS and OBN) sink to the bottom to acquire seismic data, both of which are excited while being towed in the water using independent marine seismic airgun excitation sources. The submarine seismic data acquisition cable sunk into the seabed, its working method is that the submarine seismic cable (OBC) is first dropped and laid to the seabed by the cable-releasing ship, and then the underwater controllable airgun source is towed by the airgun source ship to a certain distance below the sea surface. Go forward in depth and excite seismic signals into the seawater, and collect seabed seismic data by the seismic cables laid in advance on the seabed. After the data acquisition is completed, the submarine seismic cable is retrieved by the cable launching ship, put into a new measurement work area, and then the data acquisition operation of the submarine seismic signal is repeated. Various OBC, OBS and OBN are produced and sold by independent submarine seismic data acquisition cables and submarine seismic data acquisition stations such as ION, Sercel, Fairfield and OYO Geospace.

The submarine node seismograph exploration technology (OBN) is to place the node seismic instrument underwater without cable power supply and without communication. Each node seismic instrument operates independently, completely independent of all other nodes, and can continuously collect data for several months. OBN's data acquisition work is a two-ship operation—the source ship and the node seismic instrument deployment and recovery ship. The layout and spacing of nodal seismic instruments are not restricted, which is suitable for all-round angle exploration. When laying out nodal seismic instruments, ropes or wire cables may be attached to each nodal instrument, so that nodal seismic instruments can be recovered easily, similar to how fishermen recover long series of crab pots. When deploying nodal seismic instruments to the seabed with a water depth of several thousand meters, it is not applicable to attach ropes or wire cables. Generally, ROVs carry nodal seismic instruments and deploy instruments on the seabed according to the designed measuring point coordinates. When recovering, the ROV dives to The seabed goes to recover deepwater node seismic instruments one by one.

At present, there are two types of submarine node seismic instruments, one is the autonomous operation and completely independent of all other nodes with the help of ropes or wire cables, and the other is deployed and deployed one by one by ROVs diving to the seabed. Recovered subsea node seismic instruments operating autonomously and completely independent of all other nodes. Since there is no power supply and communication cable connected to the submarine node seismic instrument, it is impossible to provide real-time power supply or battery charging to the submarine node seismic instrument. As a result, the instrument needs to carry a large number of rechargeable batteries to ensure that it can work on the seabed for a long time, and the node seismic instrument is added. The production cost, volume and weight of the seabed node cannot be positioned on the seabed, the working status of the seabed node seismic instrument cannot be monitored in real time, and the data collected by the seabed node seismic instrument cannot be transmitted in real time (the instrument can only perform blind sampling), It is impossible to time the node seismic instruments working on the seabed. They can only rely on expensive atomic clock chips to time the instruments. When working on the seabed for a long time, the time drift of the atomic clock chip will cause timing errors.

At present, the most widely used submarine node seismic instruments in the industry use conventional three-component electronic detectors and piezoelectric crystals to collect four-component submarine seismic data. The three-component geophone is a special geophone used in multi-wave exploration. Different from single-component conventional geophones, each geophone is equipped with three mutually perpendicular sensors to record the three components of the particle vibration velocity vector, and is used to simultaneously record longitudinal waves, shear waves, and converted waves. A conventional geophone is mainly composed of a shell, a cylindrical magnetic steel, a ring spring and a coil. The magnetic steel is vertically fixed in the center of the shell, and the coil is softly connected to the shell through the upper and lower spring pieces, so that it is placed in the gap between the magnetic steel and the shell, and can move up and down. When the seismic wave reaches the surface observation point, the shell of the geophone and the magnetic steel vibrate accordingly, and the coil lags behind the magnetic steel due to inertia, forming a relative motion between the two. In such a movement, the coil cuts the magnetic field lines to generate induced electromotive force, and outputs current signals corresponding to the vibration period. These signals can be amplified and recorded by special instruments, thereby realizing the electromechanical conversion of ground vibration signals into electrical vibrations. , picked up the seismic wave. The signal voltage output by this type of detector is related to the displacement speed of its vibration, so it is called a speed detector. The characteristics of this type of geophone are: its output voltage reflects the rate of change of the displacement of the geophone shell with time, that is, the speed, and its performance indicators include natural frequency, sensitivity, coil self-flow resistance, damping, harmonic distortion and parasitic resonance. There are also practical considerations of durability, size and shape. In general, the user does not have much choice when it comes to the size and shape of the detector. Usually choose a detector with high sensitivity (damping is about 0.6), small harmonic distortion, spurious resonance frequency outside the recording frequency, and good durability.

Optical fiber sensing technology began in 1977 and developed rapidly with the development of optical fiber communication technology. Optical fiber sensing technology is an important symbol to measure the degree of informatization of a country. Optical fiber sensing technology has been widely used in military, national defense, aerospace, industrial and mining enterprises, energy and environmental protection, industrial control, medicine and health, metrology and testing, construction, household appliances and other fields, and has a broad market. There are hundreds of optical fiber sensing technologies in the world, and physical quantities such as temperature, pressure, flow, displacement, vibration, rotation, bending, liquid level, speed, acceleration, sound field, current, voltage, magnetic field and radiation have achieved different performances. sensing.

Optical fiber MEMS accelerometer is a unidirectional broadband acceleration sensor. It adopts the newly developed micro/nanotechnology (micro/nanotechnology) in the 21st century. And the outgoing waveguide is directly integrated on a tiny chip, and the optical fiber MEMS acceleration system is composed of a high-sensitivity optical fiber accelerometer and a high-speed optical fiber demodulator. This kind of sensing system has the advantages of simple structure of fiber grating sensor, small size, high sensitivity, corrosion resistance, flat frequency characteristic response, linear phase change, good consistency of technical parameters, stable and reliable performance, passive and no electricity, Anti-electromagnetic interference, the ability to realize long-distance optical signal transmission and many other advantages, as well as the advantages of high resolution and high demodulation rate of MEMS technology, are widely used in various fields.

The fiber optic geophone has the advantages of high sensitivity, wide frequency range, good high frequency response, flat frequency characteristic response, linear phase change, good consistency of technical parameters, stable and reliable performance, no electricity and passive, corrosion resistance and high temperature resistance , is the development direction of geophone technology. Compared with conventional detectors, optical fiber detectors have higher sensitivity and better high-frequency response characteristics, and can realize multi-channel, large data volume, and high-speed transmission. And because there are no electronic components at the front end, it has higher reliability, high temperature and high pressure resistance, no power supply, waterproof and corrosion resistance, long-term deployment, anti-electromagnetic interference, and small channel crosstalk.

Contents of the invention

In view of the problems existing in existing submarine node seismic instruments, the present invention provides a submarine optical fiber four-component seismic instrument system and its data acquisition method, which overcomes the low sensitivity, small dynamic range, and limited signal frequency band of conventional electronic detectors and piezoelectric hydrophones , high power consumption, and the node seismic instruments that are currently put in and recovered with ropes or steel wire ropes cannot perform real-time communication and data transmission, and also overcome the inability of the existing technology to understand the working status of the submarine node seismic instruments during operation and to perform data collection. Defects are monitored and assessed in real time. .

The submarine optical fiber four-component seismic instrument system includes multiple four-component node seismic instruments and an armored photoelectric composite cable; the side of the four-component node seismic instrument is fixed with a circular cable ring, through which the four-component Node seismic instruments are connected in series with the armored photoelectric composite cable at a certain interval; the armored photoelectric composite cable is connected to the computer on the deck or in the control instrument cabin;

Each four-component node seismic instrument is equipped with an external short-distance wireless transmission module, an external photoelectric conversion module, and an external wireless charging module. The external short-distance wireless transmission module, external photoelectric conversion module, and external wireless charging module are all passed The functional module sleeve is fixed on the armored photoelectric composite cable; the four-component node seismic instrument is connected to the computer through the armored photoelectric composite cable through the external short-distance wireless transmission module for communication and data transmission.

The armored photoelectric composite cable has a cable inside, and the outer layer is wrapped with a high-strength sheath woven with Kevlar fibers or armored with one or more layers of stainless steel wires; the cable includes Singlemode and multimode fiber optic, coaxial and twisted pair power cables.

Wherein, the four-component node seismic instrument includes a pressurized cabin in which a three-component optical fiber detector, an optical fiber sound pressure hydrophone, a three-component attitude sensor, a hydroacoustic transponder, a semiconductor light source, and an internal photoelectric conversion module, modem module, preamplifier and A/D conversion module, data storage module, atomic clock, internal short-distance wireless transmission module, rechargeable battery module module; internal wireless charging module;

The three-component optical fiber detector is installed and combined in an orthogonal coordinate system, and is placed on the bottom of the pressurized cabin for measuring the three-component seabed seismic data at the position;

The fiber optic acoustic pressure hydrophone is installed on the side of the pressurized cabin to measure the seabed pressure wave data at its location;

The three-component attitude sensor provides the three-component attitude data of the position of the three-component fiber optic detector and the fiber optic sound pressure hydrophone, which is used to perform azimuth rotation and attitude correction processing on the bottom four-component seismic data;

A hydroacoustic transponder is installed on the top of the pressurized cabin, which is used to locate it on the seabed through a long baseline, short baseline or ultra-short baseline positioning system;

The semiconductor light source provides laser signals to the three-component optical fiber detector and the optical fiber sound pressure hydrophone;

The scattered light signal reflected from the three-component fiber optic detector is converted into a corresponding electrical signal by the internal photoelectric conversion module, and the FPGA-based modulation and demodulation module receives the converted electrical signal from the three-component fiber optic detector and the fiber optic sound pressure hydrophone. The signal is modulated and demodulated into a four-component seismic signal;

The pre-amplification and A/D conversion module is used to convert the signals output by the three-component optical fiber detector, the optical fiber sound pressure hydrophone and the three-component attitude sensor into digital signals, and store them through the data storage module;

Atomic clocks provide precise timing for all collected data;

The deck power supply system provides short-distance wireless power supply and charging to the rechargeable battery module through the armored photoelectric composite cable and the internal wireless charging module; the rechargeable battery module provides power for the circuit board and electronic devices inside the four-component node seismic instrument.

Further, the pressure chamber is made of aluminum alloy or high-strength pressure-resistant composite material, and when the pressure chamber is made of aluminum alloy, an anode protection device is provided.

The pressure chamber is also equipped with watertight interfaces for data downloading and battery charging, and indicator lamps for working status of the instrument.

The three-component optical fiber detector is a three-component optical fiber detector based on an optical fiber MEMS accelerometer, comprising six or twelve optical fiber MEMS accelerometers in a mutually orthogonal structure, and each component direction is composed of a pair or two pairs Optical fiber MEMS accelerometers are superimposed in parallel; or a three-component optical fiber detector composed of a three-component optical fiber vector sensor. The three-component optical fiber vector sensor includes three solid elastic cylinders with exactly the same geometric dimensions and assembled together in a three-axis orthogonal structure. A pair of optical fibers are respectively wound on the arms at both ends of an elastic cylinder, and the wound optical fibers form the two optical fiber arms of the Michelson interferometer; inside a sealed enclosure.

The fiber optic sound pressure hydrophone is selected from any one of an amplitude modulation fiber optic sound pressure hydrophone, a phase modulation fiber optic sound pressure hydrophone, and a polarization fiber optic sound pressure hydrophone.

The present invention also provides the data acquisition method of this submarine optical fiber four-component seismic instrument system, which comprises the following steps:

(a) When collecting seabed four-component seismic data in an environment with a water depth of no more than 1000 meters, first fix the four-component node seismic instruments on the conveyor belt on the deck to the armored photoelectric composite cable according to the pre-designed spacing to form a four-component Node Seismic Instrument String;

(b) Then, the four-component node seismic instrument string connected and fixed by the armored photoelectric composite cable is released to the seabed one by one according to the location requirements of the construction design by the winch on the deck;

(c) The computer starts up each four-component node seismic instrument, self-inspects the instrument, and monitors the working status in real time through short-distance wireless transmission along the armored photoelectric composite cable;

(d) The GPS signal received by the GPS antenna on the marine seismic exploration ship is used to time each four-component node seismic instrument through the external short-distance wireless transmission module on the armored photoelectric composite cable in a wireless communication mode;

(e) When the four-component node seismic instrument is deployed on the seabed, the deck power supply system wirelessly charges the rechargeable battery module through the armored photoelectric composite cable and the internal wireless charging module or directly wirelessly supplies power to the four-component node seismic instrument;

(f) Start the sound source transducer of the long baseline or short baseline or ultra-short baseline positioning system installed on the bottom of the marine seismic data acquisition operation ship, and transmit the positioning acoustic wave signal to the seabed of the operation area, and arrange each four-component on the seabed The hydroacoustic transponder on the top of the node seismic instrument receives the signal from the sound source transducer at the bottom of the operation ship, and the positioning system performs real-time positioning for each four-component node seismic instrument;

(g) Subsequently, one or more seawater airgun source operating ships excite the airgun source sequentially according to the pre-designed source line and source excitation position, and the four-component node seismic instrument starts to collect the bottom four-component seismic data excited by the sea surface airgun source, and the four-component The pre-amplification and A/D conversion module inside the node seismic instrument converts the collected output signals of the three-component optical fiber detector, optical fiber sound pressure hydrophone and three-component attitude sensor into digital signals and stores them through the data storage module. The data in the data storage module is transmitted to the external short-distance wireless transmission module fixed on the armored photoelectric composite cable through the external short-distance wireless transmission module installed inside the submarine four-component node seismograph based on the fiber optic sensor, and then through the armored photoelectric composite cable. The photoelectric conversion module on the cable converts it into an optical signal, and transmits it to the computer in real time along the optical fiber in the armored photoelectric composite cable;

(h) When working in an environment with a water depth exceeding 1000 meters, the four-component node seismic instruments are deployed and positioned in real time one by one by deepwater ROV according to the pre-designed receiver point positions, and then one or several seawater airgun source operating ships follow the pre-designed After the designed source line and source excitation position, the airgun source is excited sequentially, and the four-component node seismic instrument starts to collect the seabed four-component seismic data excited by the air gun source on the sea surface. The preamplification and A/D conversion module inside the four-component node seismic instrument will The collected output signals of the three-component optical fiber detector, the optical fiber sound pressure hydrophone and the three-component attitude sensor are converted into digital signals and stored through the data storage module; The deepwater ROV recovers the four-component node seismic instruments one by one. After the four-component node seismic instruments are recovered on the deck, the collected seabed four-component seismic data is downloaded through the data download interface via wired or wireless, and the rechargeable battery module is wired or wirelessly downloaded. Wireless charging;

(i) According to the three-component attitude data of each four-component node seismic instrument at the data acquisition position acquired synchronously and in real time by the three-component attitude sensor, the seabed four-component seismic data at the acquisition position is transformed into the three-component ocean at the corresponding acquisition position through rotational projection Seismic data, obtain the three-component marine seismic data of the position along the vertical direction and two orthogonal horizontal directions parallel to the sea level, one of the horizontal components is the horizontal component along the extension direction of the survey line of the four-component node seismic instrument deployed on the seabed , and the other is the horizontal component perpendicular to the extension direction of the survey line of the four-component node seismic instrument;

(j) Convert the seafloor four-component seismic data converted into the corresponding data acquisition position in step (i) to process the marine seismic data, and finally obtain the longitudinal and transverse wave velocity, longitudinal and transverse wave impedance, longitudinal and transverse wave anisotropy coefficient, longitudinal and transverse wave velocity of the medium below the seabed Wave attenuation coefficient, elastic parameters, viscoelastic parameters, seismic attribute data, high-resolution geological structure imaging below the seabed, used for geological structure investigation and mineral resource exploration below the seabed, and high-resolution geology of geological mineral resources and oil and gas reservoirs below the seabed Structural imaging and comprehensive evaluation of hydrocarbon reservoirs.

Wherein, the processing of marine seismic data described in step (j) includes shaping of seismic wavelets, removal of complex multiple waves, recovery of reliable effective reflection waves from data with low signal-to-noise ratio, and application of seismic source signals. Deconvolution realizes the shaping of seismic records, improves the signal-to-noise ratio of effective reflected waves, velocity modeling, stratum division, tomography, high-frequency recovery, ghost wave removal, multiple wave elimination, deconvolution processing, various Anisotropic time domain or depth domain migration imaging, Q compensation or Q migration.

The submarine optical fiber four-component seismic instrument system and the data acquisition method thereof of the present invention have the advantages of high sensitivity, wide frequency band, good high-frequency response, flat frequency characteristic response, linear phase change, good consistency of technical parameters, and high performance. The advantages of stability and reliability, no electricity and passive, corrosion resistance and high temperature resistance are the development direction of geophone technology. Compared with conventional detectors, optical fiber detectors have higher sensitivity and better high-frequency response characteristics, and can realize multi-channel, large data volume, and high-speed transmission. And because there are no electronic components at the front end, it has higher reliability, high temperature and high pressure resistance, no power supply, waterproof and corrosion resistance, long-term deployment, anti-electromagnetic interference, and small channel crosstalk. It can overcome the defects of low sensitivity, small dynamic range, limited signal frequency band and high power consumption of conventional electronic geophones and piezoelectric hydrophones.

The submarine optical fiber four-component seismic instrument system and its data acquisition method of the present invention are suitable for low-cost submarine four-component seismic exploration data acquisition operations, and can overcome the inability of the submarine node seismic instruments currently used in the industry to perform real-time monitoring using ropes or wire ropes. Communication and data transmission, and it is impossible to understand the working status of the submarine node seismic instrument during the data acquisition operation and the real-time monitoring and evaluation of the collected data. The invention utilizes the short-distance wireless data transmission function module installed on the armored photoelectric composite cable, which can greatly reduce the manufacturing cost of the submarine node seismic instrument, reduce the volume and weight of the node seismic instrument, and ensure that all four-component node seismic instruments Acquire the four-component seismic data of the seabed when the state is intact and normal, keep the seabed node instrument working continuously on the seabed for a longer period of time, eliminate the timing and positioning errors of the seabed node seismic instrument, and ensure that the collected data will not be lost in the case of the unfortunate loss of the seabed node instrument The seabed four-component seismic data solves various problems faced by the current seabed node seismic instruments, facilitates marine seismic exploration companies to collect seabed multi-component seismic data efficiently, safely and at low cost, and provides high-efficiency and low-cost exploration and development of seabed minerals and oil and gas resources. With strong technical support, it has a good promotion and application prospect.

Description of drawings

Fig. 1 is a structural representation of a four-component node seismic instrument of the present invention;

Fig. 2 is a schematic diagram of seabed deployment of the submarine optical fiber four-component seismic instrument system of the present invention;

Fig. 3 is a structural schematic diagram of the submarine optical fiber four-component seismic instrument system of the present invention;

Fig. 4 is a plan view of the structure of the submarine optical fiber four-component seismic instrument system of the present invention.

Detailed ways

The data acquisition method of the submarine optical fiber four-component seismic instrument system of the present invention will be described in detail below in conjunction with the drawings and embodiments.

Fig. 1 is a structural schematic diagram of a four-component nodal seismic instrument of the present invention, including a pressurized cabin 1 in which a three-component optical fiber detector 10, an optical fiber acoustic pressure hydrophone 14, a three-component attitude sensor 13, and a hydroacoustic transponder are installed. 22. Semiconductor light source 16, internal photoelectric conversion module 17, modulation and demodulation module 18, preamplification and A/D conversion module 11, data storage module 12, atomic clock 19, internal short-distance wireless transmission module 5, rechargeable battery module module 20; internal wireless charging module 21;

The pressure chamber is made of aluminum alloy or high-strength pressure-resistant composite material, which is used to resist the damage of the deep seabed high pressure to the sensor and the attached electronic devices in the chamber. The aluminum alloy pressure chamber is equipped with anode protection device.

The three-component optical fiber detector 10 is installed and combined in an orthogonal coordinate system, and is placed at the bottom of the pressurized cabin 1 for measuring the three-component seismic data of the seabed at the location.

Described three-component optical fiber detector 10 is based on the three-component optical fiber detector of optical fiber MEMS accelerometer, comprises six or twelve optical fiber MEMS accelerometers and is formed by mutual orthogonal structure, and each component direction is respectively made up of a pair or two It is composed of parallel superposition of fiber optic MEMS accelerometers; or a three-component fiber optic detector composed of three-component fiber optic vector sensors. The three-component fiber optic vector sensor includes three solid elastic cylinders with exactly the same geometric dimensions and assembled into a three-axis orthogonal structure. , a pair of optical fibers are respectively wound on the arms at both ends of an elastic cylinder, and the wound optical fibers form the two optical fiber arms of the Michelson interferometer; the mass block is bonded to the orthogonal joint of the elastic cylinder, and the elastic cylinder is fixed in a sealed enclosure.

The three-component attitude sensor 13 provides the three-component attitude data of the pressurized cabin 1 where the three-component optical fiber detector 10 and the optical fiber acoustic pressure hydrophone 14 are located, and is used to perform azimuth rotation and attitude correction processing on the bottom four-component seismic data.

The fiber optic sound pressure hydrophone 14 is selected from any one of an amplitude modulation fiber optic sound pressure hydrophone, a phase modulation fiber optic sound pressure hydrophone, and a polarization fiber optic sound pressure hydrophone.

The optical fiber sound pressure hydrophone 14 is installed on the side of the pressurized cabin 1, and the sound pressure sensing head of the optical fiber sound pressure hydrophone 14 is sealed with a high-strength corrosion-resistant sound-sensitive material, and the sound pressure signal can be directly induced by contacting seawater for measurement The seabed pressure wave data at its location; the other side of the pressurized cabin is symmetrically equipped with data download and battery charging watertight interfaces and instrument working status indicators; the top of the pressurized cabin 1 is equipped with a hydroacoustic transponder 22 for Baseline or short baseline or ultra-short baseline positioning system for its positioning on the seabed.

The semiconductor light source 16 provides laser signals to the three-component optical fiber detector 10 and the optical fiber sound pressure hydrophone 14, and the scattered light signal reflected from the three-component optical fiber detector 10 is converted into a corresponding electrical signal by the photoelectric conversion module 17, based on The modulation and demodulation module 18 of FPGA modulates and demodulates the electrical signal converted into a four-component seismic signal after the three-component optical fiber detector 10 and the optical fiber sound pressure hydrophone 14 receive, and the preamplification and A/D conversion module 11 is used for The signals output by the three-component optical fiber detector 10, the optical fiber sound pressure hydrophone 14 and the three-component attitude sensor 13 are converted into digital signals, stored by the data storage module 12, and the atomic clock 19 performs accurate timing for all collected data .

The deck power supply system performs close-range wireless power supply and charging to the rechargeable battery module (20) through the armored photoelectric composite cable (3) and the internal wireless charging module (21); the rechargeable battery module (20) is a four-component node Circuit boards and electronics inside the seismic instrument provide power.

As shown in Figure 2, Figure 3 and Figure 4, the submarine optical fiber four-component seismograph system includes multiple four-component node seismic instruments and an armored photoelectric composite cable 3, and the number of four-component node seismic instruments is determined according to actual needs. The side of the four-component node seismic instrument is fixed with a circular cable ring 2, through which the four-component node seismic instrument is connected in series on the armored photoelectric composite cable 3 at a certain interval, and the interval distance is several meters to hundreds of meters. time, depending on the specific circumstances. Each four-component node seismic instrument is equipped with an external short-distance wireless transmission module 6, an external photoelectric conversion module 7, and an external wireless charging module 8, and the above modules are fixed on the armored photoelectric composite cable 3 through the functional module sleeve 4. The armored photoelectric composite cable 3 is provided with cables 9 inside, and the cables 9 include single-mode and multi-mode optical fibers, coaxial cables and twisted-pair power supply lines. The armored photoelectric composite cable 3 is connected with the computer on the deck or in the control instrument cabin.

The data acquisition method of submarine optical fiber four-component seismic instrument system of the present invention, concrete implementation process is as follows:

First, on the conveyor belt on the deck, a plurality of four-component node seismic instruments are fixed to the armored photoelectric composite cable 3 through the circular cable ring 2 on the four-component node seismic instrument according to the pre-designed spacing to form a four-component node seismic instrument Then the four-component node seismic instrument strings are put into the seabed one by one by the winch on the deck according to the location requirements of the construction design.

The computer on the deck or in the control instrument compartment starts up each four-component node seismic instrument, performs instrument self-inspection and real-time monitoring of working status along the armored photoelectric composite cable 3 through short-distance wireless transmission.

Simultaneously, the GPS signal received by the GPS antenna on the marine seismic exploration ship is used for timing service to each four-component node seismic instrument through the external short-distance wireless transmission module 6 in a wireless communication manner.

After the four-component node seismic instrument is successively laid on the seabed of the predetermined work area by the high-strength armored photoelectric composite cable 3, the emission source switch of the long baseline or short baseline or ultra-short baseline positioning system installed on the bottom of the marine seismic data acquisition operation ship is started. The transducer transmits positioning acoustic wave signals to the bottom of the work area, and the hydroacoustic transponder 22 arranged on the top of each four-component node seismic instrument on the bottom of the seabed receives the signal from the sound source transducer at the bottom of the operation ship. Component node seismic instruments for real-time positioning;

Then one or more seawater air gun source operating ships excite the air gun source sequentially according to the pre-designed source line and source excitation position, and the four-component node seismic instrument starts to collect the submarine four-component seismic data excited by the sea surface air gun source, and the four-component node seismic instrument The internal pre-amplification and A/D conversion module 11 converts the collected output signals of the three-component optical fiber detector 10, the optical fiber sound pressure hydrophone 14 and the three-component attitude sensor 13 into digital signals, and performs digital processing through the data storage module 12. Storage, the data in the data storage module 12 is transmitted to the fixed external short-distance wireless transmission module 6 on the armored photoelectric composite cable 3 through the second internal short-distance wireless transmission module 5 installed inside the four-component node seismic instrument, and then passed through the armored photoelectric composite cable 3. The external photoelectric conversion module 7 installed on the photoelectric composite cable 3 converts it into an optical signal, and transmits it to the computer in real time along the cable 9 in the armored photoelectric composite cable 3 .

When the submarine optical fiber four-component seismic instrument system is deployed on the seabed, the deck power supply system charges the rechargeable battery module 20 in the four-component node seismic instrument through the armored photoelectric composite cable 3 and the external wireless charging module 8 at the circular cable ring 2. Wireless power and charging. At the same time, the computer monitors the working status of the four-component node seismic instrument in real time through short-distance wireless transmission.

When operating in a water depth of more than 1,000 meters, the submarine optical fiber four-component seismic instrument system can be deployed and positioned in real time one by one through the deepwater ROV according to the pre-designed receiver point positions, and then one or several seawater air gun source operating ships follow the pre-designed After the designed source line and source excitation position, the airgun source is excited sequentially, and the four-component node seismic instrument starts to collect the seabed four-component seismic data excited by the air gun source on the sea surface. The preamplification and A/D conversion module inside the four-component node seismic instrument11 The collected output signals of the three-component optical fiber detector 10 , the optical fiber sound pressure hydrophone 14 and the three-component attitude sensor 13 are converted into digital signals and stored by the data storage module 12 . After the airgun source has excited all the pre-designed source signals, the deepwater ROV is used to recover the submarine optical fiber four-component seismic instrument system one by one. The data download interface on the side of the node seismic instrument performs wired or wireless downloading, and at the same time performs wired or wireless charging to the rechargeable battery module module 20 in the four-component node seismic instrument;

The submarine optical fiber four-component seismic instrument system of the present invention has the advantages of high sensitivity, wide frequency band, good high-frequency response, flat frequency characteristic response, linear phase change, good consistency of technical parameters, stable and reliable performance, and no electricity. The advantages of passive, corrosion resistance and high temperature resistance are the development direction of geophone technology. Compared with conventional detectors, optical fiber detectors have higher sensitivity and better high-frequency response characteristics, and can realize multi-channel, large data volume, and high-speed transmission. And because there are no electronic components at the front end, it has higher reliability, high temperature and high pressure resistance, no power supply, waterproof and corrosion resistance, long-term deployment, anti-electromagnetic interference, and small channel crosstalk. It can overcome the defects of low sensitivity, small dynamic range, limited signal frequency band and high power consumption of conventional electronic geophones and piezoelectric hydrophones.

The submarine optical fiber four-component seismic instrument system of the present invention is suitable for low-cost seabed four-component seismic exploration data acquisition operations, and can overcome the inability of real-time communication and data transmission of the submarine node seismic instruments that are currently used in the industry to use ropes or wire ropes, It is also impossible to understand the working status of the submarine node seismic instrument during the data acquisition operation and the real-time monitoring and evaluation of the collected data. The invention utilizes the short-distance wireless data transmission function module installed on the armored photoelectric composite cable, which can greatly reduce the manufacturing cost of the submarine node seismic instrument, reduce the volume and weight of the node seismic instrument, and ensure that all four-component node seismic instruments Acquire the four-component seismic data of the seabed when the state is intact and normal, keep the seabed node instrument working continuously on the seabed for a longer period of time, eliminate the timing and positioning errors of the seabed node seismic instrument, and ensure that the collected data will not be lost in the case of the unfortunate loss of the seabed node instrument The seabed four-component seismic data solves various problems faced by the current seabed node seismic instruments, facilitates marine seismic exploration companies to collect seabed multi-component seismic data efficiently, safely and at low cost, and provides high-efficiency and low-cost exploration and development of seabed minerals and oil and gas resources. With strong technical support, it has a good promotion and application prospect.

Claims (9)

1. The submarine optical fiber four-component seismic instrument system is characterized in that it includes a plurality of four-component node seismic instruments and an armored photoelectric composite cable (3); the side of the four-component node seismic instrument is fixed with a circular cable ring (2). The circular cable ring (2) connects the four-component node seismic instruments in series on the armored photoelectric composite cable (3) at a certain interval; the armored photoelectric composite cable (3) is connected to the computer on the deck or in the control instrument cabin connect;

   Each four-component node seismic instrument is equipped with an external short-distance wireless transmission module (6), an external photoelectric conversion module (7), an external wireless charging module (8), and the external short-distance wireless transmission module (6) , the external photoelectric conversion module (7), and the external wireless charging module (8) are all fixed on the armored photoelectric composite cable (3) through the functional module sleeve (4); The module (6) is connected with the computer through the armored photoelectric composite cable (3) in a wireless communication mode to perform communication and data transmission.
2. The submarine optical fiber four-component seismic instrument system according to claim 1, wherein said armored photoelectric composite cable (3) is internally provided with a cable (9), and the outer layer is wrapped with Kevlar fiber braided High-strength sheath or armor twisted with one or more layers of stainless steel wires; the cable (9) includes single-mode and multi-mode optical fibers, coaxial cables and twisted-pair power supply lines.
3. The submarine optical fiber four-component seismic instrument system according to claim 1, wherein the four-component node seismic instrument comprises a pressurized cabin (1), and a three-component optical fiber detector (1) is provided in the pressurized cabin (1). 10), fiber optic sound pressure hydrophone (14), three-component attitude sensor (13), underwater acoustic transponder (22), semiconductor light source (16), internal photoelectric conversion module (17), modulation and demodulation module (18) , preamplifier and A/D conversion module (11), data storage module (12), atomic clock (19), internal short-distance wireless transmission module (5), rechargeable battery module module (20); internal wireless charging module ( twenty one);

   The three-component optical fiber detector (10) is installed and combined according to an orthogonal coordinate system, and is placed on the bottom of the pressure cabin (1), for measuring the three-component seabed seismic data at the position;

   The optical fiber sound pressure hydrophone (14) is installed on the side of the pressurized cabin (1), and is used for measuring the seabed pressure wave data of its position;

   The three-component attitude sensor (13) provides the three-component attitude data of the positions of the three-component optical fiber detector (10) and the optical fiber acoustic pressure hydrophone (14), and is used to perform azimuth rotation and attitude correction processing on the bottom four-component seismic data ;

   A hydroacoustic transponder (22) is installed on the top of the pressurized cabin (1), for positioning it on the seabed by a long baseline or short baseline or ultra-short baseline positioning system;

   The semiconductor light source (16) provides laser signals to the three-component optical fiber detector (10) and the optical fiber sound pressure hydrophone (14);

   The scattered light signal reflected back from the three-component optical fiber detector (10) is converted into a corresponding electrical signal by the internal photoelectric conversion module (17), and the FPGA-based modulation and demodulation module (18) converts the three-component optical fiber detector (10) and The converted electrical signal is modulated and demodulated into a four-component seismic signal by the optical fiber sound pressure hydrophone (14) after receiving it;

   The pre-amplification and A/D conversion module (11) is used to convert the signals output by the three-component optical fiber detector (10), the optical fiber sound pressure hydrophone (14) and the three-component attitude sensor (13) into digital signals, through The data storage module (12) stores;

   Atomic clock (19) carries out precise time service to all collected data;

   The deck power supply system performs close-range wireless power supply and charging to the rechargeable battery module (20) through the armored photoelectric composite cable (3) and the internal wireless charging module (21); the rechargeable battery module (20) is a four-component node Circuit boards and electronics inside the seismic instrument provide power.
4. The submarine optical fiber four-component seismic instrument system according to claim 3, characterized in that, the pressure chamber (1) is made of aluminum alloy or high-strength pressure-resistant composite material. For the aluminum alloy pressurized cabin, an anode protection device (15) is provided.
5. The submarine optical fiber four-component seismic instrument system according to claim 3, characterized in that, said pressurized cabin (1) is also equipped with data downloading and battery charging watertight interfaces and instrument working status indicator lights.
6. The submarine optical fiber four-component seismic instrument system according to claim 3, wherein said three-component optical fiber detector (10) is a three-component optical fiber detector based on an optical fiber MEMS accelerometer, comprising six or Twelve optical fiber MEMS accelerometers are composed of mutually orthogonal structures, and each component direction is composed of one or two pairs of optical fiber MEMS accelerometers superimposed in parallel; or a three-component optical fiber detector composed of a three-component optical fiber vector sensor. The optical fiber vector sensor consists of three solid elastic cylinders with exactly the same geometric dimensions assembled together in a three-axis orthogonal structure. A pair of optical fibers are respectively wound on the two ends of an elastic cylinder. The wound optical fibers form Michelson interference. The two optical fiber arms of the instrument; the quality block is bonded to the orthogonal joint of the elastic cylinder, and the elastic cylinder is fixedly installed in the sealed shell.
7. The submarine optical fiber four-component seismic instrument system according to claim 3, wherein the optical fiber acoustic pressure hydrophone (14) is selected from an amplitude modulation optical fiber acoustic pressure hydrophone, a phase modulation optical fiber acoustic pressure hydrophone Any of the polarized fiber optic sound pressure hydrophones.
8. The data acquisition method of the submarine optical fiber four-component seismic instrument system is characterized in that, adopting the submarine optical fiber four-component seismic instrument system described in any one of claims 1 to 7, comprises the following steps:

   (a) When collecting seabed four-component seismic data in an environment with a water depth of not more than 1000 meters, first fix the four-component node seismic instruments to the armored photoelectric composite cable (3) on the conveyor belt on the deck according to the pre-designed spacing Form four-component node seismic instrument cluster;

   (b) The four-component node seismic instrument string connected and fixed by the armored photoelectric composite cable (3) will be released to the seabed one by one according to the position requirements of the construction design by the winch on the deck;

   (c) The computer starts up each four-component node seismic instrument, performs instrument self-inspection, and monitors the working status in real time along the armored photoelectric composite cable (3) through short-distance wireless transmission;

   (d) The GPS signal received by the GPS antenna on the marine seismic exploration ship is sent to each four-component node seismic instrument in a wireless communication mode through the external short-distance wireless transmission module (6) on the armored photoelectric composite cable (3) time service;

   (e) After the four-component node seismic instrument is deployed on the seabed, the deck power supply system wirelessly charges the rechargeable battery module (20) or the four-component Node seismic instruments directly provide wireless power supply;

   (f) Start the sound source transducer of the long baseline or short baseline or ultra-short baseline positioning system installed on the bottom of the marine seismic data acquisition operation ship, and transmit the positioning acoustic wave signal to the seabed of the operation area, and arrange each four-component on the seabed The hydroacoustic transponder (22) on the top of the node seismic instrument receives the signal from the sound source transducer at the bottom of the workboat, and the positioning system performs real-time positioning of each four-component node seismic instrument;

   (g) Subsequently, one or more seawater airgun source operating ships excite the airgun source sequentially according to the pre-designed source line and source excitation position, and the four-component node seismic instrument starts to collect the bottom four-component seismic data excited by the sea surface airgun source, and the four-component The preamplification and A/D conversion module (11) inside the node seismic instrument will collect the output signals of the three-component optical fiber detector (10), the optical fiber sound pressure hydrophone (14) and the three-component attitude sensor (13) converted into digital signals and stored by the data storage module (12), the data in the data storage module (12) is transmitted to the fixed on the armored photoelectric composite cable (3) through the external short-distance wireless transmission module (6) installed inside. In the external short-range wireless transmission module (6), it is converted into an optical signal by the photoelectric conversion module on the armored photoelectric composite cable (3), and is transmitted to the computer in real time along the optical fiber in the armored photoelectric composite cable (3);

   (h) When working in an environment with a water depth exceeding 1000 meters, the four-component node seismic instruments are deployed and positioned in real time one by one by deepwater ROV according to the pre-designed receiver point positions, and then one or several seawater airgun source operating ships follow the pre-designed After the designed source line and source excitation position, the airgun source is excited sequentially, and the four-component node seismic instrument starts to collect the seabed four-component seismic data excited by the air gun source on the sea surface. The preamplification and A/D conversion module inside the four-component node seismic instrument ( 11) converting the collected output signals of the three-component optical fiber detector (10), the optical fiber sound pressure hydrophone (14) and the three-component attitude sensor (13) into digital signals and storing them through the data storage module (12); After the airgun seismic source has excited all the pre-designed source signals, the deepwater ROV is used to recover the four-component node seismic instruments one by one. After the four-component node seismic instruments are recovered on the deck, the collected seabed four-component seismic data is transmitted through the data download interface. Wired or wireless downloading, and wired or wireless charging to the rechargeable battery module (20) at the same time;

   (i) According to the three-component attitude data of each four-component node seismic instrument at the data acquisition position synchronously collected by the three-component attitude sensor (13) in real time, the seabed four-component seismic data at the acquisition position is converted into the corresponding acquisition position by rotating projection Three-component marine seismic data, obtain the three-component marine seismic data along the vertical direction and two orthogonal horizontal directions parallel to the sea level, one of the horizontal components is along the extension direction of the line of the four-component node seismic instrument deployed on the seabed The horizontal component of , the other is the horizontal component perpendicular to the extension direction of the four-component node seismic instrument survey line;

   (j) Convert the seafloor four-component seismic data converted into the corresponding data acquisition position in step (i) to process the marine seismic data, and finally obtain the longitudinal and transverse wave velocity, longitudinal and transverse wave impedance, longitudinal and transverse wave anisotropy coefficient, longitudinal and transverse wave velocity of the medium below the seabed Wave attenuation coefficient, elastic parameters, viscoelastic parameters, seismic attribute data, high-resolution geological structure imaging below the seabed, used for geological structure investigation and mineral resource exploration below the seabed, and high-resolution geology of geological mineral resources and oil and gas reservoirs below the seabed Structural imaging and comprehensive evaluation of hydrocarbon reservoirs.
9. The data acquisition method of the submarine optical fiber four-component seismic instrument system according to claim 8, wherein the processing of marine seismic data described in step (j) includes shaping of seismic wavelets and removal of numerous and complicated multiple wave, recovering reliable effective reflection waves from data with low SNR, applying source signal deconvolution to realize integer shaping of seismic records, improving SNR of effective reflection waves, velocity modeling, stratigraphic division, tomography Imaging, high frequency recovery, ghost wave removal, multiple wave removal, deconvolution processing, anisotropic time domain or depth domain migration imaging, Q compensation or Q migration.

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