A method and system for estimating static correction of marine oblique cable seismic exploration data

Abstract

The present invention belongs to the field of geological exploration, and more specifically, relates to a method for estimating static corrections of marine oblique cable seismic exploration data, comprising: obtaining seismic data and seawater velocity, seafloor depth, shot point depth, and the distance between the shot point and the detector point; obtaining the ghost wave layer time of the detector point and the seafloor appearance time based on the seismic data; calculating the ghost wave delay of the detector point based on the ghost wave layer time of the detector point and the seafloor appearance time; calculating the depth of the detector point based on the ghost wave delay; calculating the static correction of the detector point based on the depth of the detector point; and calculating the static correction of the shot point based on the shot point depth and seawater velocity. The present invention utilizes the results of picking up the two layers of main reflection and cable ghost reflection to perform datum plane correction of seismic data, thereby overcoming the problem of superposition of different seismic reflection phases caused by uneven cables, while also not affecting the fluctuation characteristics of seismic waves.

Description

Technical Field

[0001] The present invention belongs to the field of geological exploration, and more particularly, relates to a method and system for estimating static corrections of marine oblique cable seismic exploration data. Background Art

[0002] Marine seismic exploration generally uses seismic workboats to tow cables for construction. The seismic workboat is equipped with an excitation system, and detection points are set on the cable according to different needs. The workboat guides the cable in the direction of the survey line, forming a seismic exploration method that excites and receives while moving.

[0003] Traditionally, the cable is parallel to the sea level (flat cable), and the static correction can be calculated based on the known excitation source, detection point depth and seawater velocity. However, in this calculation method, since the source and cable are buried at the same depth, the high wave impedance difference between seawater and air at the sea level makes the ghost reflection notch frequency a fixed value, making it difficult to eliminate the impact of ghost reflections on the effective seismic signal, that is, it is difficult to suppress ghost waves. In addition, it is difficult to ensure that the cable is always parallel to the sea level during the operation of the workboat. Therefore, for flat cable construction, the data obtained itself has large errors, making it difficult to eliminate the errors later.

[0004] In order to solve the above technical problems, a slant cable broadband seismic exploration technology has been applied in the prior art. The slant cable is a cable that intersects the sea level. Generally, the slant cable can be high at the end close to the workboat and low at the end away from the workboat, or low at the end close to the workboat and high at the end away from the workboat. It can be guided forward by the workboat to conduct marine seismic exploration. Since the depth of each detection point on the slant cable is different, the static correction amount of adjacent detection points is very different. If conventional static correction methods are used, it will have a great impact on the subsequent multiple wave removal and imaging processing, and even destroy the wave characteristics of the seismic wave. The prior art applies a static correction method for offshore slant cable broadband seismic exploration based on wave field extension. The seismic exploration is statically corrected by reconstructing the wave field. It can retain the wave characteristics of the seismic wave, but the wave field reconstruction scheme requires a large amount of computation, which in turn affects the speed of estimation. Summary of the Invention

[0005] In order to overcome at least one of the above-mentioned defects in the prior art, the present invention provides a method and system for estimating the static correction of marine oblique cable seismic exploration data, which can solve the problem of inconsistency of time differences between shot points and detection points caused by uncertain excitation and receiving depths in marine exploration, and can effectively suppress ghost waves, laying a good foundation for obtaining high-quality seismic data.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0007] A method for estimating static correction of marine oblique cable seismic exploration data is provided, comprising the following steps:

[0008] S1: Acquire seismic data as well as sea velocity, seabed depth, shot point depth, and the distance between the shot point and the receiver point;

[0009] S2: Obtain the ghost wave layer time of the detection point and the seabed appearance time based on the seismic data;

[0010] S3: The ghost wave delay at the detection point is calculated based on the ghost wave layer time and the seabed appearance time at the detection point;

[0011] S4: Calculate the detection point depth based on the detection point ghost wave delay;

[0012] S5: Calculate the static correction value of the detection point according to the depth of the detection point;

[0013] S6: The static correction of the shot point is calculated based on the shot point depth and seawater velocity.

[0014] In this scheme, the ghost wave delay of the detection point is calculated by the ghost wave layer time of the detection point and the seabed appearance time, and the static correction of the detection point and the static correction of the shot point are further calculated. It does not need to reconstruct the wave field, thereby increasing the speed of static correction estimation and obtaining more accurate static correction results to effectively suppress ghost waves, laying a good foundation for subsequent high-quality seismic data, and thus improving the success rate of geological exploration.

[0015] Preferably, the seismic data is obtained in the above step S1 specifically by acquiring the seismic data by means of oblique cable acquisition.

[0016] Preferably, the above step S2 specifically includes the following steps:

[0017] S21: Loading seismic data into the 2D observation line system information header;

[0018] S22: Modify the trace header information, put the trace number into the main survey line trace header, put the shot number into the contact line trace header, and sort and sort the modified data in three dimensions;

[0019] S23: Load the data obtained in step S22 into the interpretation system, and pick up the ghost wave layer time and seabed appearance time of the detection point.

[0020] Preferably, the conditions that need to be set before starting the above step S3 are: the seabed depth is a constant value, and the seawater speed is a constant value.

[0021] Preferably, the ghost wave delay of the detection point is calculated according to the ghost wave layer time of the detection point and the seabed appearance time in the above step S3, and the specific calculation formula is:

[0022] dT=tt w ;

[0023] Among them, dT is the ghost wave delay of the detection point, t is the ghost wave layer time of the detection point, and t w The time when the seabed appears.

[0024] Preferably, the detection point depth D is obtained by calculating the detection point ghost delay in step S4. R The specific calculation formula is:

[0025]

[0026] Where V is the velocity of seawater, D WB is the seabed depth, D R is the depth of the detection point, D s is the shot point depth, X off is the distance between the shot point and the receiver point.

[0027] Preferably, the static correction amount of the detection point calculated according to the detection point depth in the above step S5 is specifically formulated as follows:

[0028]

[0029] Preferably, the above step S6 calculates the static correction value T of the shot point according to the shot point depth and seawater velocity. s The specific calculation formula is:

[0030]

[0031] Preferably, the above-mentioned step S6 can be performed after step S1 and before step S5.

[0032] Also provided is a system for the above-mentioned method of estimating static correction of marine oblique cable seismic exploration data, comprising a workboat, a cable, a data receiving module, a data acquisition module, and a data processing and interpretation system, wherein a seismic source is fixedly provided on the workboat, a plurality of geophones are fixedly provided on the cable, the cable is connected to the workboat, the geophones are electrically connected to the data receiving module, and the data receiving module is electrically connected to the data processing and interpretation system;

[0033] The data acquisition module is used to obtain the seabed depth and seawater velocity and convert them into processable data to be transmitted to the data processing and interpretation system;

[0034] The work boat is used to move the cable;

[0035] The seismic source is used to transmit signals to the seafloor;

[0036] The geophone is used to receive the signal reflected from the seabed and convert it into processable seismic data and send it to the data receiving module;

[0037] The data receiving module transmits the received seismic data to the data processing and interpretation system;

[0038] The data processing and interpretation system is used to execute steps S2 to S6 using the received data.

[0039] Preferably, the above-mentioned seismic source is in the form of an electric spark or a cable acquisition bandwidth above 100 Hz.

[0040] Compared with the prior art, the beneficial effects are:

[0041] The present invention can accurately estimate the depth and time difference of the shot and receiver points by picking up distinguishable ghost waves of the shot points and the receiver points in the seismic data, thereby solving the problem of inconsistency of the time difference between the shot and receiver points caused by the uncertainty of the excitation and receiving depths in marine exploration, so as to obtain an ideal datum static correction effect and overcome the problem of superposition of different phases of seismic reflections caused by uneven cables. At the same time, the ghost wave delay estimation result can be used to suppress the ghost wave, which has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is a schematic flow chart of a method for estimating static corrections of marine oblique cable seismic exploration data according to embodiment 1 of the present invention;

[0043] Figure 2 3D data schematic diagram of a method for estimating static corrections of marine oblique cable seismic exploration data according to embodiment 1 of the present invention;

[0044] Figure 3 Schematic diagram of picking shot point ghost reflections in a common channel domain in a method for estimating static corrections of marine oblique cable seismic exploration data according to embodiment 1 of the present invention;

[0045] Figure 4 1 is a schematic diagram of a data cross section before applying the method for estimating static correction amounts of marine oblique cable seismic exploration data according to embodiment 1 of the present invention;

[0046] Figure 5 It is a schematic diagram of a data profile after applying the method for estimating the static correction amount of marine oblique cable seismic exploration data according to Example 1 of the present invention. DETAILED DESCRIPTION

[0047] The accompanying drawings are for illustrative purposes only and are not to be construed as limiting the present invention. To better illustrate the present embodiment, some components in the accompanying drawings may be omitted, enlarged, or reduced in size, and do not represent actual product dimensions. Those skilled in the art will appreciate that some well-known structures and their descriptions may be omitted from the accompanying drawings. The positional relationships depicted in the accompanying drawings are for illustrative purposes only and are not to be construed as limiting the present invention.

[0048] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "left", "right", "long", "short", etc. indicating the orientation or position relationship, they are based on the orientation or position relationship shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting this patent. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0049] The technical solution of the present invention is further described in detail below through specific embodiments and in conjunction with the accompanying drawings:

[0050] Example 1:

[0051] like Figures 1 to 5 A method for estimating static correction of marine oblique cable seismic exploration data is shown, comprising the following steps:

[0052] S1: Acquire seismic data as well as sea velocity, seabed depth, shot point depth, and the distance between the shot point and the receiver point;

[0053] S2: Obtain the ghost wave layer time of the detection point and the seabed appearance time based on the seismic data;

[0054] S3: The ghost wave delay at the detection point is calculated based on the ghost wave layer time and the seabed appearance time at the detection point;

[0055] S4: Calculate the detection point depth based on the detection point ghost wave delay;

[0056] S5: Calculate the static correction value of the detection point according to the depth of the detection point;

[0057] S6: The static correction of the shot point is calculated based on the shot point depth and seawater velocity.

[0058] Since the data for calculating the static correction amount of the shot point has been obtained in step S1, step S6 can be executed at any time after step S1.

[0059] In addition, it should be noted that the seismic data in this embodiment is obtained by using electric sparks or high-resolution inclined cables with an acquisition bandwidth of more than 100 Hz at the seismic source, and has a relatively high-precision shot point placement depth and the ability to clearly identify the shot point ghost waves, detection point ghost waves, and the phase axis of the detection point ghost waves associated with the shot point ghost waves in the acquired single-shot data.

[0060] The seawater velocity and seabed depth in this embodiment can be obtained by conventional means. The seabed depth can also be obtained by multiplying the seabed appearance time by the seawater velocity. The shot point depth and the distance between the shot point and the detection point are both known parameters of the tugboat.

[0061] In step S1 of this embodiment, the seismic data is obtained by acquiring the seismic data through an oblique cable acquisition method.

[0062] Since accurately picking up ghost reflections is particularly critical for the static alignment of the datum surface, and the marine environment is relatively complex, the placement of the seismic source and the cable will be affected to a certain extent, coupled with the influence of the seabed undulation, resulting in large differences in the appearance time of the main reflection wave group recorded by each shot in the same survey line, and large differences in the performance of various ghost reflections. Therefore, this will have an adverse effect on the reflections recorded by all shots and the picking of ghost reflections, and is likely to cause string phase picking. Therefore, step S2 in this embodiment specifically includes the following steps:

[0063] S21: Loading seismic data into the 2D observation line system information header;

[0064] S22: Modify the trace header information, put the trace number into the main survey line trace header, put the shot number into the tie line trace header, and sort and sort the modified data in three dimensions; specifically, put the trace number of each cable line into the main survey line trace header, and put the shot number into the tie line trace header. After completing the three-dimensional trace header modification, sort and sort again, so that each line becomes a three-dimensional body (see Figure 2 ), in each volume, pick the main reflection line and the cable ghost reflection (see Figure 3 ), which is equivalent to picking two layers in a three-dimensional volume. As for picking the time of source ghost reflections, since the focal depth is relatively stable within a shot, picking the time of source ghost reflections can be performed within the common channel domain. Avoid situations where the acquired seismic data may have a low signal-to-noise ratio or a complex wavefield due to limitations in geological conditions and acquisition conditions, which greatly complicate the picking of ghost reflections. Inaccurate picking can lead to inaccurate ghost reflection predictions, which in turn affects the accuracy of the final data.

[0065] S23: Load the data obtained in step S22 into the interpretation system, pick up the ghost wave layer time of the shot point and the ghost wave layer time of the receiver point, and the seabed appearance time.

[0066] The conditions that need to be set before starting step S3 in this embodiment are: the seabed depth is a constant value, that is, the seabed is flat; and the seawater velocity is a constant value.

[0067] In step S3 of this embodiment, the ghost wave delay of the detection point is calculated based on the ghost wave layer time of the detection point and the seabed appearance time. The specific calculation formula is:

[0068] dT=tt w;

[0069] Among them, dT is the ghost wave delay of the detection point, t is the ghost wave layer time of the detection point, and t w The time when the seabed appears.

[0070] In step S4 of this embodiment, the detection point depth D is obtained based on the ghost wave delay of the detection point. R The specific calculation formula is:

[0071]

[0072] Where V is the velocity of seawater, D WB is the seabed depth, D R is the depth of the detection point, D s is the shot point depth, X off is the distance between the shot point and the receiver point.

[0073] In step S5 of this embodiment, the static correction value of the detection point is calculated according to the depth of the detection point. The specific formula is:

[0074] Among them, T R is the static correction value of the detection point.

[0075] In this embodiment, step S6 calculates the static correction value T of the shot point based on the shot point depth and seawater velocity. s The specific calculation formula is:

[0076]

[0077] The static correction value Ts of the shot point and the static correction value T of the receiver point calculated in this embodiment are the same as those of the receiver point. R The method can then be applied to seismic data to correct the seismic data.

[0078] In this embodiment, the results of picking up the main reflection and cable ghost reflection layers can be used to correct the base plane of the seismic data. After correction, the phase axis energy is focused and the quality of the stacked section is significantly improved (see Figure 5 ), thereby overcoming the problem of superposition of different phases of seismic reflections caused by uneven cables, while not affecting the fluctuation characteristics of seismic waves.

[0079] Example 2:

[0080] The only difference between this embodiment and Example 1 is that step S6 in this embodiment is performed after step S1 and before step S2. This is because the shot point depth and seawater velocity have already been obtained in step S1, so the shot point static correction can be directly calculated after step S1. Of course, this is only a reference implementation and should not be construed as limiting this solution. In specific implementations, this solution can be implemented as long as step S6 is performed after step S1.

[0081] Example 3:

[0082] like Figure 2 The system shown is a method for estimating static corrections of marine oblique cable seismic exploration data according to Example 1 or Example 2, comprising a workboat, a cable, a data receiving module, a data acquisition module, and a data processing and interpretation system. A seismic source is fixedly mounted on the workboat, and a plurality of geophones are fixedly mounted on the cable. The cable is connected to the workboat, and the geophones are electrically connected to the data receiving module. The data receiving module and the data acquisition module are both electrically connected to the data processing and interpretation system.

[0083] Since the source (shot point) and the receiver (detection point) are fixed, the shot point depth and the distance between the shot point and the detection point can be easily determined from the nameplate of the system components or by pre-measurement.

[0084] The data acquisition module is used to obtain the seabed depth and seawater velocity and convert them into processable data to be transmitted to the data processing and interpretation system;

[0085] The work boat is used to move the cable;

[0086] The seismic source is used to transmit signals to the seafloor;

[0087] The geophone is used to receive the signal reflected from the seabed and convert it into processable data and send it to the data receiving system;

[0088] The data receiving system sends the processable data to the data processing and interpretation system;

[0089] The data processing interpretation system is used to perform the following steps using the processable data:

[0090] Obtain the ghost wave layer time of the detection point and the seabed appearance time based on seismic data;

[0091] The ghost wave delay at the detection point is calculated based on the ghost wave layer time at the detection point and the seabed appearance time;

[0092] The depth of the detection point is calculated based on the ghost wave delay of the detection point;

[0093] The static correction value of the detection point is calculated according to the depth of the detection point;

[0094] The static correction of the shot point is calculated based on the shot point depth and seawater velocity.

[0095] The cable in this embodiment can be an oblique cable.

[0096] The seismic source in this embodiment is in the form of an electric spark, or a cable (which can also be understood as a detector) with a collection bandwidth of more than 100 Hz.

[0097] The present invention is described with reference to the flowcharts or block diagrams of the methods, devices (systems), and computer program products of the embodiments of the present application. It should be understood that each process or block in the flowchart or block diagram, as well as the combination of processes or blocks in the flowchart or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart or block diagram. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0098] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

[0099] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A method for estimating static correction of marine oblique cable seismic exploration data, characterized in that: The following steps are involved: S1: Acquire seismic data as well as sea velocity, seabed depth, shot point depth, and the distance between the shot point and the receiver point; S2: Obtain the ghost wave layer time of the detection point and the seabed appearance time based on the seismic data; S3: The ghost wave delay at the detection point is calculated based on the ghost wave layer time and the seabed appearance time at the detection point; S4: Calculate the detection point depth based on the detection point ghost wave delay; S5: Calculate the static correction value of the detection point according to the depth of the detection point; S6: Obtain the static correction of the shot point based on the shot point depth and seawater velocity; In step S3, the ghost wave delay of the detection point is calculated based on the ghost wave layer time of the detection point and the seabed appearance time. The specific formula is: dT=t-t w ; Among them, dT is the ghost wave delay of the detection point, t is the ghost wave layer time of the detection point, and t w The time when the seabed appears; the depth of the detection point D is calculated according to the ghost wave delay of the detection point in step S4 R The specific calculation formula is: Where V is the velocity of seawater, D WB is the seabed depth, D R is the depth of the detection point, D s is the shot point depth, X off is the distance between the shot point and the receiver point.

2. The method for estimating static correction of marine oblique cable seismic exploration data according to claim 1, characterized in that: Step S2 specifically includes the following steps: S21: Loading the seismic data into a two-dimensional observation line system information header; S22: Modify the trace header information, put the trace number into the main survey line trace header, put the shot number into the contact line trace header, and sort and sort the modified data in three dimensions; S23: Load the data obtained in step S22 into the interpretation system, and pick up the ghost wave layer time and seabed appearance time of the detection point.

3. The method for estimating static correction of marine oblique cable seismic exploration data according to claim 2, characterized in that: The conditions that need to be set before starting step S3 are: the seabed depth is a constant value, and the seawater speed is a constant value.

4. The method for estimating static correction of marine oblique cable seismic exploration data according to claim 3, characterized in that: The specific formula for calculating the static correction value of the detection point according to the detection point depth in step S5 is: Among them, T R is the static correction value of the detection point.

5. The method for estimating static correction of marine oblique cable seismic exploration data according to claim 4, characterized in that: Step S6 calculates the static correction value T of the shot point based on the shot point depth and seawater velocity. s The specific calculation formula is:

6. The method for estimating static correction of marine oblique cable seismic exploration data according to claim 5, characterized in that: Step S6 may be performed after step S1 and before step S5.

7. A system for the method of estimating static correction of marine oblique cable seismic exploration data according to any one of claims 1 to 6, characterized in that: The system comprises a workboat, a cable, a data receiving module, a data acquisition module and a data processing and interpretation system, wherein a seismic source is fixedly provided on the workboat, a plurality of geophones are fixedly provided on the cable, the cable is connected to the workboat, the geophones are electrically connected to the data receiving module, and the data receiving module and the data acquisition module are both electrically connected to the data processing and interpretation system; The data acquisition module is used to obtain the seabed depth and seawater velocity and convert them into processable data to be transmitted to the data processing and interpretation system; The working vessel is used to drive the cable to move, and the seismic source on the working vessel transmits signals to the seabed; The geophone is used to receive the signal reflected from the seabed and convert it into processable seismic data and send it to the data receiving module; The data receiving module transmits the received seismic data to the data processing and interpretation system; The data processing and interpretation system is used to execute steps S2 to S6 using the received data.

8. The system for estimating static correction of marine oblique cable seismic exploration data according to claim 7, characterized in that: The seismic source is in the form of an electric spark or the cable acquisition bandwidth is above 100 Hz.

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