CN109975875A - A kind of received vertical-rise cable system for acquiring seismic data and method at random - Google Patents

Abstract

The invention discloses a randomly received vertical cable seismic data acquisition system and method. The system includes a fixing and releasing section, a power and working section, and a straightening and positioning section, which are sequentially connected from bottom to top. The method includes a system configuration, a system There are five steps of deployment, data collection, system recycling and data processing. The invention adopts the technical scheme of installing hydrophones on the receiving channel at random positions, a certain number of hydrophones can obtain a longer vertical cable length, improve the observable range, and reduce the research and development cost; the same length and the same number Hydrophone, random position reception can achieve seismic detection effect of small track spacing; deep-sea small thrusters can adjust the posture of the cable underwater, which is more conducive to obtaining reflected seismic signals of different target geological bodies. The system of the invention has stable operation and high flexibility, and can connect multiple cable receiving sections according to different exploration targets, so as to meet the exploration needs of deep-sea geology and mineral resources of different types and scales.

Description

A random receiving vertical cable seismic data acquisition system and method

technical field

The invention relates to the field of ocean survey, in particular to a randomly received vertical cable seismic data acquisition system and method.

Background technique

The survey of marine geology and mineral resources is a basic and strategic survey activity, in which seismic detection methods play an important role in the survey of seabed structures and mineral resources. Due to the long distance from the seabed and the low signal-to-noise ratio of conventional sea surface towed earthquakes, the resolution generally can only meet the needs of shallow sea engineering exploration, and cannot meet the needs of high-resolution exploration of deep sea oceans.

In recent years, Vertical Cable Seismic (VCS) at home and abroad has provided a means of high-resolution and high signal-to-noise ratio detection in deep sea and ocean. However, foreign vertical cables are generally used in connection with the Ocean Bottom Seismometer (OBS), and there are also vertical cables fixed to the seabed for sulfide surveys, with a maximum working water depth of 2000m. There are two main types of domestic vertical cables, which can be used independently or towed, but are mainly used in offshore engineering exploration and military target monitoring. The current vertical cables are all integrated cables with fixed length and track spacing, resulting in insufficient flexibility of the equipment, limited adaptability to detection targets of different sizes and scales, and failure of the entire cable can easily cause the entire cable to fail to work. . In addition, deep-sea oceanic seismic detection is a very expensive scientific research and investigation activity, and the operating area is generally far away (for example, my country is mainly concentrated in the southwestern Indian Ocean, Atlantic Ocean, Pacific Ocean and other sea areas), and deep-sea detection has the pressure resistance and overall Integration has high requirements, coupled with its technological monopoly, equipment development is difficult and expensive. The operating mode of multiple cable detection exacerbates the cost of detection activities.

It can be seen that although the vertical cable has the advantages of high resolution and high signal-to-noise ratio detection, the flexibility of the equipment and the cost of construction make the vertical cable still greatly affected in the seismic detection for the purpose of deep-sea ocean geological structure and mineral resources survey. limits.

SUMMARY OF THE INVENTION

Aiming at the deficiencies in the above problems, the present invention provides a random reception vertical cable seismic data acquisition system and method.

In order to achieve the above object, on the one hand, the present invention provides a randomly received vertical cable seismic data acquisition system, the system includes a fixing and releasing section, a power and working section, a straightening and positioning section which are sequentially connected from bottom to top;

The fixing and releasing section includes a heavy anchor, an acoustic releaser with a ranging function, a pressure sensor and a first floating ball group sequentially connected by a Kevlar rope; the heavy anchor is used to fix the system on the seabed surface, so the The acoustic releaser is used to complete the recovery of the system, the pressure sensor is used to record pressure data, and the first float group is used to straighten the system to avoid bottoming of the equipment below;

The power and working section includes a power supply and control platform, a data receiving cable and a second floating ball group; the data receiving cable is equipped with a hydrophone responsible for recording vibration signals and an attitude meter responsible for recording the position and attitude. The position of the device in the data receiving cable is randomly distributed; the power supply and control platform is used to complete the system power supply and system control work, and a second floating ball group is installed above the power supply and control platform;

The straightening and positioning section includes an acoustic transponder connected by a Kevlar rope for determining the position of the point and a third floating ball group for straightening the entire system, the third floating ball group being located in the entire system the topmost.

Further, in the fixing and releasing section, the acoustic releaser with the ranging function works in combination with two sets of equipment to improve the reliability of the system release, and the release hooks of the two releasers are connected by a steel chain, and The steel chain is passed through the steel ring, and the steel ring is connected to the heavy anchor by Kevlar rope.

Further, in the power and working section, the distribution of the hydrophones is designed by using a segmental random sampling strategy; the data receiving cables are connected in segments, and multiple sub-segments are used for connection in the actual cable assembly; The number of hydrophones is n, and the number of densely spaced grid points is N. The hydrophones are randomly distributed at n random positions in the N equally spaced grid positions. The layout scheme of the hydrophones is as follows:

1) Divide N points into n segments; when N is an integer multiple of n, it can be divided equally, and each segment has int(N/n) points; when N is not an integer multiple of n, after equal division There are still n _r =N-int(N/n)*n points left, where int() is a rounding operation;

2) Among the n segments, randomly select n _r segments; then randomly assign the remaining n _r points into the selected n _r segments;

3) From the n segments processed in step 2), randomly select a point as the installation position of the hydrophone.

Further, in the power and work section, the attitude meter is installed at the 1/4 and 3/4 positions of each sub-section, so as to ensure that the attitude meter can be evenly distributed when multiple sub-sections are connected, so as to facilitate the reception of measurement data. Attitude information of the cable.

Further, the hydrophone is selected with sufficient pressure resistance and sufficient power supply, and on the basis of the preliminary acquisition of the size and range of the detection target from the existing data, the selection of the appropriate reference track spacing refers to the use of cables that are distributed at regular intervals. track spacing.

Further, in the power and work section, the power supply and control platform has two battery compartments and an acquisition control compartment, which respectively complete the system power supply and system control; the two battery compartments are connected to the acquisition control compartment in parallel, and the acquisition control The bin is connected to the data receiving cable through a 16-core watertight cable.

Further, in the power and working section, the small deep-sea thruster is connected to the power supply and control platform through a cable, and is used to control the attitude of the data receiving cable.

On the other hand, the present invention provides a randomly received vertical cable seismic data acquisition method, comprising the following steps:

1) System configuration: Before deployment, you need to know the high-precision terrain information of the operating area, and the operating position cannot exceed the maximum working water depth of the system; according to the weight of the system and the parameters of the floating ball, calculate the configuration of the three sets of floating ball groups of the whole system With the combination (size and quantity), the buoyancy of the system in water is guaranteed to be 1.5 to 2.0 times the weight;

2) System deployment: deploy into the sea in the order of straightening and positioning section, power and working section, fixing and releasing section, and finally sink the system to the seabed by the dead weight of the heavy anchor and fix it on the seabed surface; release it through acoustics The device deck unit calls the acoustic transponder and the acoustic release to confirm that the equipment is working properly;

3) Data collection: The hydrophone in the data receiving cable is responsible for recording the vibration signal, and the attitude meter is responsible for recording the attitude of the location;

4) System recovery: call the acoustic releaser through the acoustic releaser deck unit; the acoustic releaser receives the acoustic control signal from the ship, controls its release hook to open, completes the separation from the shackle, the heavy anchor stays on the seabed, and the rest floats and recovers ;

5) Data processing: use the reconstruction method based on compressed sensing to reconstruct the randomly distributed data collected to obtain regular grid data. Mainly, the Curvelet transform is selected as the sparse transformation of seismic data, and the accelerated iterative threshold method is used for data reconstruction, as follows:

The sampling process of seismic data can be expressed as:

b=Rf, (1)

in, is the sampled seismic data, is the sampling matrix (n<N≤2n), Regular seismic data.

Using Curvelet transform as the sparse transform of seismic data, f has sparsity in the sparse transform domain S, then (1) can be transformed into:

b=Ax with A:=RS ^* , (2)

where * represents conjugation. The coefficients of f in S (with only k non-zero values) are the sparse representation of f.

Mathematically, it has been proved that (2) can still be solved, provided that the constrained equidistant properties are satisfied. The random theory shows that the above goals can be achieved when R is a Gaussian random matrix with an independent consistent distribution. At this time, the following questions need to be solved:

Wherein, ||x|| ₀ :=#{x, x _i ≠0} is the l ₀ norm of x, and x _i is the ith item of x. Rewrite the constrained problem (3) as an unconstrained problem using the Lagrange multiplier method:

here, is an estimate of x.

We use the iterative threshold method to solve (4), the scheme is as follows:

Among them, i is the iteration index index, θ is the threshold, which gradually decreases with the number of iterations, is the step size to ensure the stability and convergence speed of the iterative algorithm, is the threshold algorithm.

Stop iterating when the threshold is lower than 10 ^-5 of the maximum value of the sparse domain, and get the solution result And then get the final data reconstruction result

Further, before the system is deployed, the power supply and control platform is used to set the clock with the time server or GPS to obtain the high-precision initial time and complete the time synchronization of each primitive.

The beneficial effects of the present invention are:

(1) Install the hydrophones on the receiving channel in a random receiving method, a certain number of hydrophones can obtain a longer vertical cable length, improve the observable range, reduce the detection cost, and improve the observation effect;

(2) The small deep-sea thruster can adjust the posture of the cable under water, keep it vertical or inclined at a certain angle, which is more conducive to obtaining the reflected seismic signals of different target geological bodies and expands the detection range of conventional cables;

(3) The receiving cable adopts the combined connection design of multiple sub-sections, which can conveniently and flexibly complete the expansion and adjustment of the system according to different detection targets, and improve the adaptability of the system to the observation target;

(4) The maximum working water depth is 6000m, which can meet the needs of my country's current deep-sea ocean mine resource survey with high-resolution EDM source or bottom tow low-frequency sound source.

Description of drawings

Fig. 1 is the overall composition schematic diagram of vertical cable seismic data acquisition system of the present invention;

Fig. 2 is the schematic diagram of fixing and releasing section in Fig. 1;

Fig. 3 is the schematic diagram of the arrangement scheme of the hydrophone in the data receiving cable in Fig. 1;

Fig. 4 is the schematic diagram of the power and working section in Fig. 1 and the comparison diagram with the conventional cable;

Fig. 5 is the schematic diagram of power supply and control platform in Fig. 1;

Fig. 6 is the schematic diagram of straightening and positioning section in Fig. 1;

Figure 7 is a graphical representation of data and reconstruction results collected using a cable of 32 primitives;

Figure 8 is a schematic diagram of a tilt random cable using a small deep-sea thruster;

In the figure: 1. Fixing and releasing section; 2. Power and working section; 3. Straightening and positioning section; 1.1. Heavy anchor; 1.2. Steel ring; 1.3. Steel chain; 1.4. Shackle; 1.5. Release hook; ; 1.8 pressure sensor; 1.9 first float group; 1.10 fixed and release section Kevlar rope; 2.1 data receiving cable; 2.2 hydrophone; 2.3 attitude instrument; 2.4 power supply and control platform; 2.4.1 stabilizer; 2.4. 2 battery compartment; 2.4.3 acquisition control compartment; 2.4.4 four-core watertight air plug (male); 2.4.5 first four-core watertight air plug (female); 2.4.6 second four-core watertight air plug ( 2.4.7 Sixteen-core watertight aerial plug (female); 2.5 The second float group; 3.1 Kevlar rope for straightening and positioning section; 3.2 Acoustic transponder; 3.3 The third float group.

Detailed ways

The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

Example 1

Embodiments of the present invention provide a randomly received vertical cable seismic data acquisition system and method.

In a first aspect of the present invention, a random reception vertical cable seismic data acquisition system is provided.

As shown in Figure 1, the system includes a fixing and releasing section 1, a power and working section 2, and a straightening and positioning section 3 that are connected in sequence from bottom to top;

As shown in Figure 2, the fixing and releasing section 1 includes a heavy anchor 1.1, a steel ring 1.2, a steel chain 1.3, a shackle 1.4, a release hook 1.5, a fixing frame 1.6, an acoustic release 1.7, a pressure sensor 1.8, and a first floating ball group 1.9 and 1.10 of the Kevlar cord for securing and releasing segments. The heavy anchor 1.1 is used to fix the whole system on the seabed, and is connected to the steel ring 1.2 by the Kevlar rope 1.10 of the fixing and releasing section. The acoustic release 1.7 uses a combination of two sets of equipment to improve the reliability of the system release. The release hooks 1.5 of the two releasers 1.7 are connected by a steel chain 1.3, and the steel chain 1.3 passes through the steel ring 1.2. The two acoustic releasers 1.7 are fixed together by a fixing frame 1.6 made of polyurethane solid material, and work at the same time to play the role of double insurance. A pressure sensor 1.8 for measuring and storing water pressure information data at the location is installed on the Kevlar rope 1.10 of the fixing and releasing section above, and is connected to the first float group 1.9.

As shown in FIG. 3 , when arranging the positions of the hydrophone 2.2 in the data receiving cable 2.1, a part of the positions selected by a piecewise random sampling strategy is adopted on the basis of regular and dense distribution. The piecewise random sampling has the spectral characteristics of "blue noise", which is beneficial to the subsequent reconstruction processing. There are two cases here: 1) The densely spaced grid points are an integer multiple of the number of hydrophones, and 31 is the distribution of conventional cable hydrophones. Segmentation is performed first, with 2 points per segment; A location was randomly selected as the hydrophone location, and the final design was obtained. 2) The densely spaced grid points are not an integer multiple of the number of hydrophones, 33 is the distribution of conventional cable hydrophones, segmented first, 2 points per segment, and 1 point left; then randomize the point It is adjusted to a certain segment; 34 means that a location is randomly selected from each segment as the location of the hydrophone, and the final design scheme is obtained.

As shown at 41 in Figure 4, the power and work section 2 includes a data receiving cable 2.1, a hydrophone 2.2, an attitude indicator 2.3, a power supply and control platform 2.4 and a second float group 2.5. Among them, various sensors are installed in the deep-sea data receiving cable 2.1 filled with liquid silicone oil, including the hydrophone 2.2 and the attitude meter 2.3. The inside of the data receiving cable is stressed through Kevlar ropes; each channel uses 4 hydrophones superimposed, and the hydrophones use piezoelectric deep-sea spherical hydrophones, which can work normally in the 6000m deep sea; the attitude indicator 2.3 is installed on the cable. 1/4 and 3/4 positions.

Here are a few concepts first. The randomly received vertical cables of the present invention are obtained by sampling through a certain random strategy (this embodiment adopts a segmented random sampling strategy) on the basis of conventional cables with equal channel spacing. The track spacing is called the reference track spacing of the randomly distributed cable, the number of corresponding conventional cables is called the reference track number of the randomly distributed cable, and the ratio of the actual track number to the reference track number is called the sampling ratio of the randomly distributed cable. 41 in Figure 4 shows a cable with a total of 16 receiving channels and a length of 160 m. The distance between the reference tracks is 5m, the number of reference tracks is 32, and the sampling ratio is 1/2. In Fig. 4, 42 shows cables with a spacing of 5m, 32 channels and a length of 160m. It can be seen that the present invention can save the cost of 16 channels and a total of 64 hydrophones and obtain cables of the same length. According to the conventional method of equal-spaced track spacing, only a receiving cable with a track spacing of 5m and 16 tracks with a length of 80m can be obtained (shown as 43 in Figure 4); , the performance of collecting data is greatly reduced.

As shown in Figure 5, the power supply and control platform 2.4 includes a stable frame 2.4.1, two battery compartments 2.4.2 and a collection control compartment 2.4.3. The interface on the battery compartment 2.4.2 is the four-core watertight aerial plug (male) 2.4.4, which can be connected to the first four-core watertight aerial plug (female) 2.4 on the acquisition control compartment 2.4.3 through the watertight connector. 5 on. The second four-core watertight aerial plug (female) 2.4.6 on the acquisition control compartment 2.4.3 is used to connect the time server, and the sixteen-core watertight aerial plug (female) 2.4.7 is connected to the data receiving cable through the watertight connector On the specific interface of 2.1, the transmission function of power supply and control signal is realized.

As shown in Figure 6, the straightening and positioning section 3 includes a straightening and positioning section Kevlar rope 3.1, an acoustic transponder 3.2 and a third floating ball group 3.3. The acoustic transponder 3.2 plays the function of assisting ranging and positioning. The third floating ball group 3.3 is composed of multiple floating balls, which are used to straighten the whole system. The reasonable configuration quantity is calculated by buoyancy, so that the vertical cable can be kept vertical or nearly vertical on the seabed. state.

In a second aspect of the present invention, a randomly received vertical cable seismic data acquisition method is provided, comprising the following steps:

Step 1: System configuration. Before deployment, you need to know the high-precision topographic information of the operation area. The operation position should not exceed the maximum working water depth of the system. Select a relatively flat area as the area to deploy the system; The configuration and combination (size and quantity) of the three sets of floating ball groups;

Step 2: System deployment. Correct the attitude meter 2.3 of the small deep-sea thruster 2.6 and the attitude meter 2.3 of the data receiving cable 2.1 before launching. Arranged into the sea in the order of straightening and positioning section 3, power and working section 2, fixing and releasing section 1 (see Figure 1), and finally sink the whole system to the seabed by the dead weight of heavy anchor 1.1, and fixed it on the seabed surface ;

Step 3: Data acquisition. Power and work section 2 begins to collect and store data. Among them, each hydrophone 2.2 is responsible for recording the vibration signal, and the attitude meter 2.3 is responsible for recording the attitude of the location. In addition, the pressure sensor 1.6 records water pressure information data;

Step 4: System Recycling. When the workboat arrives at 500m to 1000m near the water entry point of the system, call and communicate with the acoustic releaser 1.7 through the acoustic releaser deck unit, at least confirm that one of them is working normally, and collect distance information. When ready, use the deck unit to signal the release of the acoustic release 1.7. The acoustic releaser 1.7 receives the acoustic control signal on the ship, controls its release hook 1.5 to open, completes the separation from the shackle 1.4, the heavy anchor 1.1 is left on the seabed, and the rest are recovered.

Step 5: Data processing. The acquired data is a randomly distributed data, and two methods can be used for data processing. First, data reconstruction is performed first to obtain data at regular positions, and then subsequent normalized processing is performed; data reconstruction methods based on compressed sensing can be used for processing. The second is to directly use this randomly distributed data for imaging processing. Both methods have high feasibility.

As shown in Figure 7, 71 is the seismic data collected by using 16 random receiving traces, 5m reference trace spacing, and 160m long vertical cables, which are irregular data with random missing traces. Through data reconstruction processing, regular seismic trace data including 32 traces and 5m trace spacing as shown in 72 are obtained.

The overall structure of the present invention is relatively light, and when using 2 collection sections (16 random receiving channels, 5m reference channel spacing, 160m long) for work, the weight of the whole system in air is about 500kg (excluding cement block heavy anchors), and the water in water is about 500kg. Under the action of the floating ball, it presents a state of positive buoyancy, and it basically stands upright on the seabed surface in the deep sea where the bottom current is small. The design of the dual acoustic release 1.7 improves the working stability of the system. According to the size and scope of the detection target, the number of acquisition sections and the length of the cable can be flexibly adjusted to meet the exploration needs of different types and scales of deep-sea sulfide deposits. The maximum working water depth of the system is 6000m, and the hydrophone can achieve wide-band (10Hz-6kHz) reception. With high-resolution EDM source or bottom tow low-frequency sound source, it can meet the requirements of deep-sea high-resolution geological structures, natural gas hydrates, polymetallic sulfides The demand for detection of mineral resources such as minerals. The design of the power supply and control platform greatly reduces the complexity of the entire system, making it easier to deploy and recycle equipment.

Example 2

As shown in Figure 8, a small deep-sea thruster 2.6 is added to control the attitude of the vertical cable.

The small deep-sea thruster 2.6 carries an attitude meter, and the attitude meter reading is corrected before launching into the water; it is connected to the control platform 2.4 through a cable and power supply, and the data information of the attitude meter 2.3 installed in the data receiving cable 2.1 can be obtained.

When the inclination direction of the data receiving cable 2.1 is changed according to the detection target, the direction and magnitude of the propulsion force are automatically adjusted by comparing its own attitude information with the cable attitude information obtained by the attitude meter 2.3 on the cable, so that the data receiving cable 2.1 is kept vertical or certain inclinations and inclinations.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims (10)

1. A randomly received vertical cable seismic data acquisition system is characterized by comprising a fixing and releasing section (1), a power and working section (2) and a straightening and positioning section (3) which are sequentially connected from bottom to top;

the fixing and releasing section (1) comprises a heavy anchor (1.1), an acoustic releaser (1.7) with a distance measuring function, a pressure sensor (1.8) and a first floating ball group (1.9) which are sequentially connected through a Kevlar (1.10); the heavy anchor (1.1) is used for fixing the system on the seabed surface, the acoustic releaser (1.7) is used for completing system recovery, the pressure sensor (1.8) is used for recording pressure data, and the first floating ball group (1.9) is used for straightening the system to avoid bottoming of equipment below;

the power and working section (2) comprises a data receiving cable (2.1), a power supply and control platform (2.4) and a second floating ball group (2.5); hydrophones (2.2) responsible for recording vibration signals and an attitude instrument (2.3) responsible for recording the position and the attitude of the hydrophones are arranged in the data receiving cable (2.1), and the positions of the hydrophones (2.2) in the data receiving cable (2.1) are randomly distributed; the power supply and control platform (2.4) is used for completing system power supply and system control work, and a second floating ball group (2.5) is arranged above the power supply and control platform (2.4);

the straightening and positioning section (3) comprises an acoustic transponder (3.2) which is connected by a Kevlar rope (3.1) and is used for determining the position of the point, and a third floating ball group (3.3) used for straightening the whole set of system, wherein the third floating ball group (3.3) is positioned at the topmost end of the whole set of system.

2. The vertical cable seismic data acquisition system with random receiving function as claimed in claim 1, characterized in that in the fixed and release section (1), the acoustic releaser (1.7) with the distance measuring function works by using two sets of equipment in combination, the reliability of system release is improved, the release hooks (1.5) of the two releasers (1.7) are connected through a steel chain (1.3), the steel chain (1.3) passes through a steel ring (1.2), and the steel ring (1.2) is connected with a heavy anchor (1.1) through a Kevlar (1.10).

3. A random access vertical cable seismic data acquisition system according to claim 1, wherein the distribution of hydrophones (2.2) in the power and operating section (2) is designed using a piecewise random sampling strategy; the data receiving cable (2.1) is connected in sections, and a plurality of subsections are used for connection in an actual cable assembly; in the data receiving cable (2.1), the number of hydrophones is N, the number of dense equal-interval grid points is N, the hydrophones are randomly distributed on N random positions in the N equal-interval grid positions, and the arrangement scheme of the hydrophones is as follows:

1) divide N points inton sections; when N is integer multiple of N, the method can be equally divided, and each segment has int (N/N) points; when N is not an integer multiple of N, N remains after the division_rN-int (N/N) × N points, where int () is a rounding operation;

2) of the n segments, n is randomly selected_rEach section; then n will remain_rPoints are randomly included in the selected n_rIn each section;

3) randomly extracting one point position from the n sections processed in the step 2) to serve as the installation position of the hydrophone.

4. A randomly received vertical cable seismic data acquisition system according to claim 3, wherein said attitude indicator (2.3) is mounted at the 1/4 and 3/4 position of each sub-section in said power and working section (2) to ensure that the attitude indicator (2.3) is uniformly distributed when a plurality of sub-sections are connected, so as to measure and calculate the attitude information of the data receiving cable (2.1).

5. The randomly received vertical cable seismic data acquisition system according to claim 1, wherein in the power and working section (2), the hydrophones (2.2) are selected to have sufficient pressure resistance and sufficient power supply, and a proper reference trace interval is selected on the basis of the size and range of a detection target preliminarily obtained from existing data.

6. A randomly received vertical cable seismic data acquisition system according to claim 1, wherein in said power and working section (2), said power and control platform (2.4) has two battery compartments (2.4.2) and one acquisition control compartment (2.4.3) for respectively performing system power supply and system control; the two battery bins (2.4.2) are connected in parallel to the acquisition control bin (2.4.3), and the acquisition control bin (2.4.3) is connected to the data receiving cable (2.1) through a 16-core watertight cable.

7. A randomly received vertical cable seismic data acquisition system according to claim 1, characterized in that in said power and working section (2) the small deep sea thruster (2.6) is connected by cable to the power and control platform (2.4) for controlling the attitude of the data receiving cable (2.1).

8. A method for randomly received vertical cable seismic data acquisition, comprising the steps of:

1) system configuration: according to the weight of the system and parameters of the floating balls, calculating the configuration and combination of three sets of floating ball groups of the whole system, and ensuring that the buoyancy of the system in water is 1.5-2.0 times of the weight;

2) system laying: the straightening and positioning section (3), the power and working section (2) and the fixing and releasing section (1) are sequentially arranged in the sea, and finally the system is sunk into the sea bottom by the dead weight of the heavy anchor (1.1) and fixed on the surface of the sea bottom; calling the acoustic transponder (3.2) and the acoustic releaser (1.7) through the acoustic releaser deck unit to determine that the equipment works normally;

3) data acquisition: a hydrophone (2.2) in the data receiving cable (2.1) is responsible for recording vibration signals, and an attitude instrument (2.3) is responsible for recording the attitude of the position where the hydrophone is located;

4) and (3) system recovery: calling the acoustic releaser (1.7) through the acoustic releaser deck unit; the acoustic releaser (1.7) receives an acoustic control signal on the ship, controls a release hook (1.5) thereof to open, completes the separation from the shackle (1.4), keeps the heavy anchor (1.1) on the sea bottom, and floats upwards and recovers the rest part;

5) data processing: and (3) reconstructing the collected randomly distributed data by using a reconstruction method based on compressed sensing, and performing conventional data processing after reconstructing the randomly distributed data into regular grid data.

9. The method for acquiring randomly received vertical cable seismic data according to claim 8, wherein in the data processing of step 5), Curvelet transform (Curvelet transform) is selected as sparse transform of seismic data, and an accelerated iteration threshold method is adopted for data reconstruction, specifically as follows:

the sampling process of seismic data can be expressed as:

b＝Rf, (1)

wherein,is a sampling of the seismic data and,is a sampling matrix (n)<N≤2n),Is regular seismic data.

Using Curvelet transform as the sparse transform for seismic data, f having sparsity in the sparse transform domain S, then (1) can be translated into:

b＝Ax with A:＝RS^*, (2)

wherein denotes conjugation.The coefficients in S, which are f (only k non-zero values), are a sparse representation of f.

Mathematically, it has been shown that (2) can still be solved, provided that the restricted equidistant characteristics satisfy the stochastic theory that this goal is achieved when R is a gaussian random matrix with independent uniform distribution. The following problem needs to be solved at this time:

wherein | x | Y calculation₀:＝#{x,x_iNot equal to 0} is l of x₀Norm, x_iThe i-th term of x. The lagrange multiplier method is used to rewrite the constrained problem (3) to an unconstrained problem:

here, ,is an estimate of x.

We solve for (4) using an iterative thresholding method, the scheme is as follows:

wherein i is an iteration index, theta is a threshold value, gradually decreases along with the iteration times,the step length is ensured, the stability and the convergence speed of the iterative algorithm are ensured,is a threshold algorithm.

Iterate to 10 with threshold below sparse domain maximum^-5Stopping iteration to obtain the solution resultFurther obtain the final data reconstruction result

10. A method for randomly received vertical cable seismic data acquisition according to claim 8, wherein the system is clocked by the power and control platform (2.4) with a time server or GPS to obtain high precision initial time before deployment to achieve time synchronization of each element.