A method for detecting seismic multiple

Abstract

This invention discloses a method for detecting seismic multiples. The method includes: picking up reflecting interfaces; setting a formation velocity between every two adjacent reflecting interfaces; setting a shot point sequence and a receiver sequence at each reflecting interface; setting a source function; establishing a propagation operator sequentially for each shot point in the shot point sequence based on the formation velocity; determining the up-going and down-going wave fields generated at each reflecting interface based on the propagation operators; establishing propagation extrapolations for down-going and up-going secondary sources for each reflecting interface based on the up-going and down-going wave fields; and summing the wave fields detected at the receiver sequence by combining the propagation extrapolations of the down-going and up-going secondary sources to obtain the detection result of seismic multiples. This method can improve the detection accuracy and precision of multiples.

Description

Technical Field

[0001] This invention relates to the field of geophysical exploration technology, and in particular to a method for detecting multiple seismic waves. Background Technology

[0002] Seismic multiples refer to the phenomenon where seismic waves from the same source arrive at the receiving point multiple times due to reflection and refraction by the strata during propagation in the subsurface medium. Typically, during seismic exploration, the receiving point receives multiples propagating from different paths from the source, leading to waveform complexity. The waveforms and amplitudes of these multiples then affect subsequent seismic data processing and interpretation. Detecting seismic multiples can further improve the accuracy of seismic data processing and reduce uncertainties in data interpretation. Therefore, in the seismic data processing stage, it is necessary to predict and separate seismic multiples. Among existing technologies, τ-p is a technique used in seismic data processing, particularly suitable for the analysis and prediction of multiples. It effectively separates different types of waves, including multiples, by converting seismic wave data from the spatial domain to the τ-p (time-tilt) domain. However, at near offsets, because the difference in propagation time between primary reflections and multiples is small, and this method increases with the propagation time of seismic waves, it cannot completely detect all multiples. Summary of the Invention

[0003] To address the aforementioned technical problems, at least one embodiment of the present invention provides a method for detecting seismic multiples, which is used to detect the spatial location of multiples in seismic data, thereby improving the detection accuracy and precision of multiples.

[0004] In some optional embodiments, the method includes the following steps:

[0005] Pick up the reflective interface;

[0006] Set the formation velocity between every two adjacent reflective interfaces.

[0007] At each reflecting interface, a sequence of shot points and a sequence of receiver points are set.

[0008] Define the source function;

[0009] Based on the formation velocity, a propagation operator is sequentially established for each shot point in the shot point sequence;

[0010] Based on the propagation operator, an up-row wave field and a down-row wave field are generated at each reflecting interface;

[0011] For each reflecting interface, the propagation extrapolation of the downlink secondary source and the uplink secondary source is established based on the uplink and downlink wave fields;

[0012] By combining the propagation extrapolation of the downlink secondary source and the uplink secondary source, the wavefields detected at the receiver sequence are superimposed and summed to obtain the detection results of seismic multiples.

[0013] In some alternative embodiments, the picking of the reflection interface includes: picking the reflection interface based on seismic data in the post-stack depth domain.

[0014] In some optional embodiments, the expression for the source function is:

[0015] Where τ is the width and center frequency of the control waveform, and t is the propagation time.

[0016] In some optional embodiments, the expression for the propagation operator is W = W0(t) * exp(-i2πf / v).

[0017] In some optional embodiments, the expression for the downlink wave field is P. + (z m ,z0)=W + *S, the expression for the ascending wave field is P - (z m ,z0)=W - *S, where z m z is the depth corresponding to the current reflective interface, and z0 is the starting depth.

[0018] In some optional embodiments, the propagation extrapolation of the downlink secondary source is ΔS. + =R(z) n )P - (z n ,z0)+T(z n )P + (z n The propagation extrapolation of the uplink secondary source is ΔS (z0). - =R(z) n )P + (z n ,z0)+T(z n )P - (z n ,z0), where T(z n R(z) is the transmission coefficient. n P is the reflection coefficient. - (z n (z0) represents the ascending wave field, P + (z n z0) represents the downlink wave field, z n The current depth of the reflective interface.

[0019] In some optional embodiments, the expression for the summation is: in, This represents the ascending wave field at the receiver point. This represents the downlink wave field at the detector point.

[0020] At least one embodiment of the present invention also provides a seismic multiple wave detection device, characterized in that it comprises:

[0021] The interface picking module is used to pick up the reflected interface;

[0022] The velocity filling module is used to set the formation velocity between every two adjacent reflective interfaces.

[0023] The shot-detector setting module is used to set the shot point sequence and detector point sequence at each reflecting interface.

[0024] The source setting module is used to set the source function;

[0025] The operator construction module is used to sequentially build a propagation operator for each shot point in the shot point sequence based on the formation velocity.

[0026] The wave field determination module is used to determine, based on the propagation operator, the up-going wave field and down-going wave field generated at each reflection interface;

[0027] The extrapolation module is used to establish the propagation extrapolation of the downlink secondary source and the uplink secondary source for each reflecting interface based on the uplink and downlink wave fields.

[0028] The multiple wave detection module is used to combine the propagation extrapolation of the downlink secondary source and the uplink secondary source, and to superimpose and sum the wave fields detected at the receiver sequence to obtain the detection results of seismic multiple waves.

[0029] At least one embodiment of the present invention also provides an electronic device, characterized in that it comprises:

[0030] At least one processor; and,

[0031] A memory communicatively connected to the at least one processor; wherein,

[0032] The memory stores instructions that can be executed by the at least one processor to enable the at least one processor to perform the seismic multiple wave detection method as described above.

[0033] At least one embodiment of the present invention also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the seismic multiple wave detection method as described above.

[0034] At least one embodiment of the present invention also provides a computer program product, including a computer program that, when executed by a processor, implements the steps of the seismic multiple wave detection method as described above.

[0035] Compared with existing technologies, the present invention provides a method for detecting seismic multiples. Based on the phenomenon that seismic waves propagating in the subsurface medium can arrive multiple times at the receiving point due to reflection and refraction by the strata, the method utilizes post-stack depth-domain seismic data to pick up reflection interfaces, set strata velocities, shot point and receiver sequence, and define the source function. Then, at each picked reflection interface, an up-going wavefield and a down-going wavefield are generated. Propagation extrapolation of the down-going and up-going secondary sources is then established, and the wavefields recorded at the receiver sequence are superimposed and summed to obtain the detection result of seismic multiples. Compared with traditional methods, the seismic multiple detection method proposed in this invention can effectively improve the detection accuracy and precision of multiples. Attached Figure Description

[0036] One or more embodiments are illustrated by way of example with reference to the accompanying drawings, and these illustrative descriptions do not constitute a limitation on the embodiments.

[0037] Figure 1 This is a flowchart of the steps of the seismic multiple wave detection method used in Embodiment 1 of the present invention;

[0038] Figure 2 This is a schematic diagram of post-stack depth domain seismic data according to Embodiment 2 of the present invention;

[0039] Figure 3 This is a schematic diagram of the reflective interface picked up according to Embodiment 2 of the present invention;

[0040] Figure 4 This is a schematic diagram of the velocity model obtained after filling the space between the reflective interfaces according to Embodiment 2 of the present invention;

[0041] Figure 5 This is a schematic diagram of the source function and frequency constructed according to Embodiment 2 of the present invention;

[0042] Figure 6 This is a schematic diagram of the seismic multiple wave detection results in Embodiment 2 of the present invention. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the various embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details are presented in the embodiments of the present invention to facilitate a better understanding of the invention. However, the technical solutions claimed in the present invention can be implemented even without these technical details and various variations and modifications based on the following embodiments. The division of the following embodiments is for ease of description and should not constitute any limitation on the specific implementation of the present invention. The various embodiments can be combined with and referenced by each other without contradiction.

[0044] The implementation details of the above method are described in detail below through examples. The following content is only for the convenience of understanding the implementation details and is not necessary for implementing this solution.

[0045] Example 1:

[0046] like Figure 1 As shown, this embodiment provides a method for detecting seismic multiples. This method can accurately identify the spatial location of multiples in seismic data from land or sea. The specific implementation steps include, but are not limited to, the following steps:

[0047] Step 1: Based on the post-stack depth domain seismic data D obs (depth) Picks the reflective interface.

[0048] The expression for the reflective interface is R = {R0, R1, ..., R...} n},

[0049] Where R is the reflective interface, R0 represents the first interface, which is usually the land surface or the ocean surface, and n is the number of reflective interfaces picked up.

[0050] Step 2: Set the formation velocity between every two adjacent reflective interfaces.

[0051] The expression for formation velocity is v = {v1, v2, ..., v}. m},

[0052] Where v represents the formation velocity between the two picked-up reflection interfaces, m represents the number of set formation velocities, and m≤n;

[0053] Step 3: Set the shot point sequence and receiver point sequence at each reflecting interface, where:

[0054] The expression for the shot sequence is G. source ={S1(x,y,z),S2(x,y,z),...,S p (x,y,z)}

[0055] The expression for the detector point sequence is G. receiver ={Rc1(x,y,z),Rc2(x,y,z),...,Rc q (x,y,z)}

[0056] Among them, G source G represents the sequence of shots. receiver represents the sequence of receiver points, represents the three-dimensional spatial location, p is the number of shot points, and q is the number of receiver points;

[0057] Step 4: Set the source function.

[0058] The expression for the source function is:

[0059] Where τ is the width and center frequency of the control waveform, and t is the propagation time.

[0060] Step 5: Based on the velocity model obtained from the filling process, establish propagation operators sequentially for each shot point in the shot point sequence.

[0061] The expression for the propagation operator is W = W0(t) * exp(-i2πf / v).

[0062] An upward wave field and a downward wave field are generated at each captured reflection interface R, where:

[0063] The expression for the downward wave is P + (z m ,z0)=W + *S,

[0064] The expression for an upward wave is P - (z m ,z0)=W - *S,

[0065] Among them, z m z0 is the depth corresponding to the current reflective interface, and z0 is the starting depth.

[0066] Step Six: For each reflection interface, establish propagation extrapolations for the downlink and uplink quadratic sources based on the propagation operators, where:

[0067] The expression for the downlink quadratic source is ΔS + =R(z) n )P - (z n ,z0)+T(z n )P + (z n ,z0),

[0068] The expression for the upward quadratic source is ΔS - =R(z)n )P + (z n ,z0)+T(z n )P - (z n ,z0),

[0069] Wherein, T(z) n R(z) is the transmission coefficient. n P is the reflection coefficient. - (z n (z0) represents the ascending wave field, P + (z n z0) represents the downlink wave field, z n The current depth of the reflective interface;

[0070] Step 7: Combining the propagation extrapolation of the downlink and uplink secondary sources, the wavefields recorded at the receiver sequence are superimposed and summed to obtain the detected seismic multiples, where:

[0071] The expression for summation is:

[0072] in, This represents the ascending wave field at the receiver point. This represents the downlink wave field at the detector point.

[0073] Example 2

[0074] The technical solution of the present invention and its beneficial effects will be further illustrated below with a specific example.

[0075] Figure 2 The post-stack depth domain seismic data of this embodiment is shown, where the longitudinal direction represents the true depth and the transverse direction represents the location. The reflection interface exhibits obvious amplitude and waveform changes in the post-stack seismic profile.

[0076] Figure 3 The image shows the reflective interface obtained by this embodiment, where the reflective interface exhibits obvious outliers in the data;

[0077] Figure 4 This embodiment shows the velocity model obtained after filling the space between the reflective interfaces with velocity.

[0078] Figure 5 The source function and frequency constructed in this embodiment are shown, wherein, Figure 5 (a) is the source function. Figure 5 (b) is the frequency. The center frequency of the source is 20Hz. Using the source function, a propagation operator is established to realize the calculation of wave field extrapolation.

[0079] Figure 6The results of seismic multiple detection in this embodiment are shown. These results are consistent with the theoretical amplitude and travel time results, indicating that the accuracy of the detected seismic multiples meets the requirements.

[0080] The above embodiments fully illustrate the method proposed in this invention specifically for detecting seismic multiples: Based on the phenomenon that seismic waves, due to reflection and refraction by the strata during propagation in the subsurface medium, will arrive multiple times at the receiving point due to the same source, this method utilizes post-stack depth-domain seismic data to pick up reflection interfaces, set stratum velocities, shot point and receiver sequence, and define the source function. Then, at each picked reflection interface, an up-going wavefield and a down-going wavefield are generated. Propagation extrapolation of the down-going and up-going secondary sources is then established, and the wavefields recorded at the receiver sequence are superimposed and summed to obtain the detection result of seismic multiples. Compared to traditional methods, this method can significantly improve the detection accuracy and precision of seismic multiples.

[0081] Example 3

[0082] Another embodiment of the present invention relates to a seismic multiple wave detection device, comprising:

[0083] The interface picking module is used to pick up the reflected interface;

[0084] The velocity filling module is used to set the formation velocity between every two adjacent reflective interfaces.

[0085] The shot-detector setting module is used to set the shot point sequence and detector point sequence at each reflecting interface.

[0086] The source setting module is used to set the source function;

[0087] The operator construction module is used to sequentially build a propagation operator for each shot point in the shot point sequence based on the formation velocity.

[0088] The wave field determination module is used to determine, based on the propagation operator, the up-going wave field and down-going wave field generated at each reflection interface;

[0089] The extrapolation module is used to establish the propagation extrapolation of the downlink secondary source and the uplink secondary source for each reflecting interface based on the uplink and downlink wave fields.

[0090] The multiple wave detection module is used to combine the propagation extrapolation of the downlink secondary source and the uplink secondary source, and to superimpose and sum the wave fields detected at the receiver sequence to obtain the detection results of seismic multiple waves.

[0091] Example 4:

[0092] Another embodiment of the present invention relates to an electronic device, comprising: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, the instructions being executed by the at least one processor to enable the at least one processor to perform the seismic multiple wave detection method of the above embodiments.

[0093] The memory and processor are connected via a bus, which can include any number of interconnecting buses and bridges, connecting various circuits of one or more processors and memories. The bus can also connect various other circuits, such as peripheral devices, voltage regulators, and power management circuits, which are well known in the art and will not be described further herein. The bus interface provides an interface between the bus and the transceiver. The transceiver can be a single element or multiple elements, such as multiple receivers and transmitters, providing a unit for communicating with various other devices over a transmission medium. Data processed by the processor is transmitted over the wireless medium via an antenna, which further receives data and transmits it to the processor.

[0094] The processor manages the bus and general processing, and also provides various functions, including timing, peripheral interfaces, voltage regulation, power management, and other control functions. Memory is used to store data used by the processor during operation.

[0095] Example 5:

[0096] Another embodiment of the present invention relates to a computer-readable storage medium storing a computer program. When executed by a processor, the computer program implements the seismic multiple wave detection method of the above embodiments.

[0097] That is, those skilled in the art will understand that all or part of the steps in the methods of the above embodiments can be implemented by a program instructing related hardware. This program is stored in a storage medium and includes several instructions to cause a device (which may be a microcontroller, chip, etc.) or processor to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0098] Example 6

[0099] Another embodiment of the present invention relates to a computer program product, including a computer program that, when executed by a processor, implements the steps of the seismic multiple wave detection method of the above embodiments.

[0100] Those skilled in the art will understand that the above embodiments are specific embodiments for implementing the present invention, and in practical applications, various changes in form and detail may be made without departing from the spirit and scope of the present invention.

Claims

1. A method for detecting multiple seismic waves, characterized in that, include: Pick up the reflective interface; Set the formation velocity between every two adjacent reflective interfaces. At each reflecting interface, a sequence of shot points and a sequence of receiver points are set. Define the source function; Based on the formation velocity, a propagation operator is sequentially established for each shot point in the shot point sequence; Based on the propagation operator, an up-row wave field and a down-row wave field are generated at each reflecting interface; For each reflecting interface, the propagation extrapolation of the downlink secondary source and the uplink secondary source is established based on the uplink and downlink wave fields; By combining the propagation extrapolation of the downlink secondary source and the uplink secondary source, the wavefields detected at the receiver sequence are superimposed and summed to obtain the detection results of seismic multiples.

2. The seismic multiple wave detection method according to claim 1, characterized in that, The picking of reflection interfaces includes: picking reflection interfaces based on seismic data in the post-stack depth domain.

3. The seismic multiple wave detection method according to claim 1, characterized in that, The expression for the source function is: Where τ is the width and center frequency of the control waveform, and t is the propagation time.

4. The seismic multiple wave detection method according to claim 3, characterized in that, The expression for the propagation operator is W = W0(t) * exp(-i2πf / v), where v is the formation velocity and f is the frequency.

5. The seismic multiple wave detection method according to claim 4, characterized in that, The expression for the downlink wave field is P + (z m ,z0)=W + *S, the expression for the ascending wave field is P - (z m ,z0)=W - *S, where z m z is the depth corresponding to the current reflective interface, and z0 is the starting depth.

6. The seismic multiple wave detection method according to claim 5, characterized in that, The propagation extrapolation of the downlink secondary source is ΔS + =R(z) n )P - (z n ,z0)+T(z n )P + (z n The propagation extrapolation of the uplink secondary source is ΔS (z0). - =R(z) n )P + (z n ,z0)+T(z n )P - (z n ,z0), where T(z n R(z) is the transmission coefficient. n P is the reflection coefficient. - (z n (z0) represents the ascending wave field, P + (z n z0) represents the downlink wave field, z n The current depth of the reflective interface, z0 is the starting depth.

7. The seismic multiple wave detection method according to claim 6, characterized in that, The expression for the superposition and summation is: in, This represents the ascending wave field at the receiver point. This represents the downlink wave field at the detector point.

8. A seismic multiple wave detection device, characterized in that, include: The interface picking module is used to pick up the reflected interface; The velocity filling module is used to set the formation velocity between every two adjacent reflective interfaces. The shot-detector setting module is used to set the shot point sequence and detector point sequence at each reflecting interface. The source setting module is used to set the source function; The operator construction module is used to sequentially build a propagation operator for each shot point in the shot point sequence based on the formation velocity. The wave field determination module is used to determine, based on the propagation operator, the up-going wave field and down-going wave field generated at each reflection interface; The extrapolation module is used to establish the propagation extrapolation of the downlink secondary source and the uplink secondary source for each reflecting interface based on the uplink and downlink wave fields. The multiple wave detection module is used to combine the propagation extrapolation of the downlink secondary source and the uplink secondary source, and to superimpose and sum the wave fields detected at the receiver sequence to obtain the detection results of seismic multiple waves.

9. An electronic device, characterized in that, include: At least one processor; as well as, A memory communicatively connected to the at least one processor; wherein, The memory stores instructions that can be executed by the at least one processor to enable the at least one processor to perform the seismic multiple wave detection method as described in any one of claims 1 to 7.

10. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements the seismic multiple wave detection method according to any one of claims 1 to 7.

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