Point source seismic wave field simulation method and device, electronic equipment and storage medium

Abstract

The invention belongs to the field of oil exploration, and relates to a point source seismic wave field simulation method and device, electronic equipment and a storage medium. The method comprises the following steps: selecting observation system parameters to be simulated, and giving a reference speed; calculating a quality factor Q by using the well bypass seismic data; calculating a seismic data spectrum, and determining an effective frequency range of seismic data; calculating the speed of each frequency in the frequency range by using the reference speed and Q; calculating spherical wave response under each frequency; calculating the product of the spherical wave response and the seismic wavelet spectrum in the effective frequency range; and calculating inverse Fourier transform of the product to obtain a time domain seismic reflection wave field and an incident wave field excited by the point seismic source. The invention provides a point source excitation seismic wave field simulation method which can be used for seismic wave field simulation and wave field characteristic research and analysis, enhancing understanding of a seismic wave field propagation rule and guiding links such as acquisition, processing and interpretation of seismic exploration.

Description

Technical Field

[0001] The present invention belongs to the technical field of seismic exploration, and provides a point source seismic reflection wavefield simulation method closer to the actual situation, and specifically relates to a point source seismic wavefield simulation method, device, electronic device and storage medium. Background Art

[0002] At present, most seismic processing, interpretation methods and technologies are based on plane wave theory, such as deconvolution technology, prestack AVO analysis and AVA inversion, post-stack impedance inversion, etc. Their description of the wavefield reflection characteristics is based on one of the most important theoretical bases in current seismic exploration - Zoeppritz equation or its linear approximation. However, in actual field seismic acquisition, a point source is used, and the excited wave is a spherical wave rather than a plane wave. In seismic exploration, the reflection characteristics of seismic waves are usually utilized. In order to further develop more accurate seismic exploration methods and technologies, it has very important theoretical value and practical significance to study and analyze the propagation characteristics and laws of spherical reflected waves in the medium based on the point source spherical wave theory.

[0003] The present invention provides a method for simulating a point source seismic reflection wavefield. Using this method, the reflection wavefield of the actual underground medium can be more accurately described, enabling us to better understand the propagation characteristics of the seismic wavefield in the actual underground medium. Summary of the Invention

[0004] The research and analysis of the point source seismic reflection characteristics have important theoretical value and practical significance for the development of seismic exploration technology. The present invention provides a method for simulating a point source seismic wavefield (spherical wave), which can accurately describe the reflection wavefield of the actual underground medium, improve the understanding of the propagation law of the actual seismic wavefield, and thus provide useful guidance for seismic acquisition, processing and interpretation.

[0005] To achieve the above object, the present invention provides a point source seismic wavefield simulation method, including:

[0006] Select the observation system parameters to be simulated and give a reference velocity;

[0007] Calculate the quality factor Q using the seismic data of the well side trace;

[0008] Calculate the spectrum of the seismic data and determine the effective frequency range of the seismic data;

[0009] Calculate the velocity of each frequency using the reference velocity and Q within the effective frequency range;

[0010] Calculate the spherical wave response at each frequency;

[0011] Then calculate the product of the spherical wave response and the seismic wavelet spectrum within the effective frequency range;

[0012] Calculate the inverse Fourier transform of the above product to obtain the time-domain seismic reflection wavefield and incident wavefield excited by the point source.

[0013] Further, the given reference velocity includes the longitudinal wave velocity reference velocities c 1ref and c 2ref of the upper and lower layer media given according to the simulation requirements.

[0014] Further, calculate the quality factor Q using the spectral ratio method based on the seismic data of the well-side trace.

[0015] Further, determine that the effective frequency range of the seismic data is f1~f2, and the dominant frequency is fp;

[0016] Within the frequency range f1~f2, calculate the velocity c(f) corresponding to each frequency according to the following formula:

[0017]

[0018] where f is the frequency, c ref is the reference velocity, f ref is the reference frequency, the reference frequency can be the dominant frequency, and i is the imaginary unit.

[0019] Further, calculate the spherical wave reflection response P ref (f) at each frequency according to the following formula:

[0020]

[0021] where is the plane wave reflection coefficient, ρ 1 and ρ 2 are the densities of the upper and lower layer media respectively, c 1 (f) and c 2 (f) are the longitudinal wave velocities of the upper and lower layer media respectively, θ is the incident angle, ω is the angular frequency and ω = 2πf, r is the offset, R is the propagation distance from the source to the receiver and R = r / sinθ, and t is the propagation time.

[0022] Removing the B(θ) term in the above formula gives the spherical incident wave response at each frequency.

[0023] Further, calculating the product of the spherical wave response and the seismic wavelet spectrum includes:

[0024] Select the wavelet used in the forward simulation, and then calculate its spectrum, denoted as W(f);

[0025] Calculate the reflection wavefield S refl (f) in the frequency domain according to the following formula:

[0026] S refl (f) = W(f)P ref(f).

[0027] Further, perform an inverse Fourier transform on the reflected wave field in the frequency domain to obtain the reflected wave field in the time domain excited by a point source; remove the B(θ) term in the above formula to obtain the incident wave field in the time domain excited by a point source.

[0028] According to another aspect of the present invention, there is provided a point-source seismic wave field simulation device, including:

[0029] A given velocity module, select the observation system parameters to be simulated, and give a reference velocity;

[0030] A factor calculation module, calculate the quality factor Q using the seismic data of the well-side trace;

[0031] A frequency determination module, calculate the spectrum of the seismic data, and determine the effective frequency range of the seismic data;

[0032] A velocity calculation module, calculate the velocity at each frequency using the reference velocity and Q within the effective frequency range;

[0033] A response calculation module, calculate the spherical wave response at each frequency;

[0034] A product calculation module, then calculate the product of the spherical wave response and the seismic wavelet spectrum within the effective frequency range;

[0035] A wave field simulation module, calculate the inverse Fourier transform of the above product to obtain the time-domain seismic reflected wave field and incident wave field excited by a point source.

[0036] According to another aspect of the present invention, there is provided an electronic device, the electronic device includes:

[0037] A memory, storing executable instructions;

[0038] A processor, the processor runs the executable instructions in the memory to implement the point-source seismic wave field simulation method.

[0039] According to another aspect of the present invention, there is provided a non-transitory computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the point-source seismic wave field simulation method is implemented.

[0040] The present invention proposes a point-source excited seismic wave field simulation method, which can be used for seismic wave field simulation and wave field characteristic research and analysis, enhance the understanding of the propagation law of seismic wave fields, and guide the acquisition, processing, and interpretation of seismic exploration. Description of the Drawings

[0041] The above and other objects, features, and advantages of the present invention will become more apparent by describing the exemplary embodiments of the present invention in more detail with reference to the accompanying drawings, in which, in the exemplary embodiments of the present invention, the same reference numerals generally represent the same components.

[0042] Figure 1 It is a flowchart of the point source seismic wave field simulation method according to the present invention.

[0043] Figure 2 It is a schematic diagram of a two-layer medium model according to an embodiment of the present invention.

[0044] Figure 3 It is a comparison diagram of the spherical reflected wave excited by the point source simulated by this method and the incident wave according to an embodiment of the present invention. Specific Embodiments

[0045] The preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to make the present invention more thorough and complete, and to fully convey the scope of the present invention to those skilled in the art.

[0046] The present invention belongs to the field of oil exploration and relates to a method for simulating a point source seismic wave field. First, select the observation system parameters to be simulated and give a reference velocity; calculate the quality factor Q using the seismic data near the well; calculate the spectrum of the seismic data to determine the effective frequency range of the seismic data; calculate the velocity at each frequency using the reference velocity and Q within this frequency range; calculate the spherical wave response at each frequency; then calculate the product of the spherical wave response and the seismic wavelet spectrum within the effective frequency range; calculate the inverse Fourier transform of the above product to obtain the time-domain seismic reflection wave field and incident wave field excited by the point source. The results can be used to analyze the characteristics of the spherical reflected wave field, enhance the understanding of the propagation law of the seismic wave field, and guide the acquisition, processing, and interpretation of seismic exploration.

[0047] Embodiment 1

[0048] As Figure 1 shown, the present invention provides a method for simulating a point source seismic wave field, including:

[0049] Select the observation system parameters to be simulated and give a reference velocity;

[0050] Calculate the quality factor Q using the seismic data near the well;

[0051] Calculate the spectrum of the seismic data to determine the effective frequency range of the seismic data;

[0052] Calculate the velocity at each frequency using the reference velocity and Q within the effective frequency range;

[0053] Calculate the spherical wave response at each frequency;

[0054] Then calculate the product of the spherical wave response and the seismic wavelet spectrum within the effective frequency range;

[0055] Calculate the inverse Fourier transform of the above product to obtain the time-domain seismic reflection wave field and incident wave field excited by the point source.

[0056] Furthermore, specifying the reference velocity includes specifying the reference velocities c 1ref 、c 2ref of the P-wave velocities of the upper and lower layer media according to the simulation requirements.

[0057] Furthermore, calculate the quality factor Q using the spectral ratio method based on the seismic data of the well-side trace.

[0058] Furthermore, determine the effective frequency range of the seismic data as f1~f2, and the dominant frequency as fp;

[0059] Within the frequency range f1~f2, calculate the velocity c(f) corresponding to each frequency according to the following formula:

[0060]

[0061] where f is the frequency, c ref is the reference velocity, f ref is the reference frequency, the reference frequency can be the dominant frequency, and i is the imaginary unit.

[0062] Furthermore, calculate the spherical reflection wave response P ref (f) at each frequency according to the following formula:

[0063]

[0064] where is the plane wave reflection coefficient, ρ 1 、ρ 2 are the densities of the upper and lower layer media respectively, c 1 (f)、c 2 (f) are the P-wave velocities of the upper and lower layer media respectively, θ is the incident angle, ω is the angular frequency and ω = 2πf, r is the offset, R is the propagation distance from the source to the receiver and R = r / sinθ, t is the propagation time; removing the B(θ) term in the above formula gives the spherical incident wave response at each frequency.

[0065] Furthermore, calculating the product of the spherical wave response and the seismic wavelet spectrum includes:

[0066] Select the wavelet used in the forward simulation, and then calculate its spectrum, denoted as W(f);

[0067] Calculate the reflected wavefield S refl (f) in the frequency domain according to the following formula:

[0068] S refl (f) = W(f)P ref (f).

[0069] Furthermore, perform the inverse Fourier transform on the reflected wavefield in the frequency domain to obtain the reflected wavefield in the time domain excited by the point source; remove the B(θ) term in the above formula to obtain the incident wavefield in the time domain excited by the point source.

[0070] Example 2

[0071] This example provides a method for simulating the seismic wavefield of a point source, including the following steps:

[0072] Step 1: Given the reference velocities c 1ref and c 2ref of the longitudinal wave velocities of the upper and lower layer media according to the simulation requirements.

[0073] Step 2: Calculate the quality factor Q using the spectral ratio method based on the seismic data of the well-side trace.

[0074] Step 3: Calculate the spectrum of the seismic data, and determine the dominant frequency fp and the effective frequency range f1 to f2 of the seismic data.

[0075] Step 4: Calculate the velocity c(f) corresponding to each frequency within the frequency range f1 to f2 according to the following formula:

[0076]

[0077] where f is the frequency, c ref is the reference velocity, f ref is the reference frequency, the reference frequency can be the dominant frequency, and i is the imaginary unit.

[0078] Step 5: Calculate the spherical reflection response P ref (f) at each frequency according to the following formula.

[0079]

[0080] where is the plane wave reflection coefficient, ρ 1 and ρ 2 are the densities of the upper and lower layer media respectively, c 1 (f), c 2(f) are the P-wave velocities of the upper and lower media respectively, θ is the incident angle, ω is the angular frequency and ω = 2πf, r is the offset, R is the propagation distance from the source to the receiver and R = r / sinθ, and t is the propagation time. Removing the B(θ) term from the above equation gives the spherical incident wave response at each frequency.

[0081] Step 6: Select the wavelet used in the forward simulation, and then calculate its spectrum, denoted as W(f).

[0082] Step 7: Calculate the reflected wave field S in the frequency domain according to the following formula refl (f):

[0083] S refl (f) = W(f)P ref (f).

[0084] Step 8: Perform the inverse Fourier transform on the above-mentioned reflected wave field in the frequency domain to obtain the reflected wave field in the time domain excited by the point source; removing the B(θ) term from the above equation gives the incident wave field in the time domain excited by the point source.

[0085] Example 3

[0086] Appendix Figure 2 This is a schematic diagram of the two-layer medium model and related parameters involved in the present invention. The densities and P-wave velocities of the upper and lower media are ρ 1 , c 1 and ρ 2 , c 2 respectively. The interface is located at z = 0 (horizontal r-axis). S is the source. The spherical wave excited by the point source S reaches the interface between the two media at the incident angle θ and is reflected, and the spherical reflected wave is received at the receiving point P.

[0087] Refer to Figure 2 and Figure 3 shown to illustrate the implementation process of the present invention with an example. The model parameters are c 1 = 2000 m / s, ρ 1 = 2.0 g / cm 3 , c 2 = 2500 m / s, ρ 2 = 2.0 g / cm 3 ; c 1 , c 2 are the reference velocities of the upper and lower media. The source is 200 m (h = 200 m) above the interface, and the receiving position is 200 m (z = 200 m) above the interface; the incident angle is θ = 5°; the frequency range is 5 - 50 Hz; the case of very small test absorption attenuation is considered, Q = 10000; the Ricker wavelet with a main frequency of 20 Hz is selected as the seismic wavelet, and the reference frequency is set to 20 Hz.

[0088] Substitute the above parameters into the following formula,

[0089]

[0090] and the corresponding spherical reflected wave response can be calculated. To facilitate the comparison between the spherical reflected wave and the incident wave, both waveforms are normalized.

[0091] Appendix Figure 3 The thick line in the figure is the spherical reflected wave obtained by the present invention, and the thin line is the corresponding incident wave. The waveform of the spherical incident wave is still the Ricker wavelet, and the wavelet shape remains unchanged; while the waveform of the spherical reflected wave is distorted and the side lobes are no longer symmetric, which is caused by the frequency-dependent effect of spherical wave reflection, that is, the reflection coefficients of different frequency components in the spherical wave are different.

[0092] Example 4

[0093] This embodiment provides a point source seismic wave field simulation device, including:

[0094] A given velocity module that selects the observation system parameters to be simulated and gives a reference velocity;

[0095] A factor calculation module that calculates the quality factor Q using the seismic data of the well-side trace;

[0096] A frequency determination module that calculates the spectrum of the seismic data and determines the effective frequency range of the seismic data;

[0097] A velocity calculation module that calculates the velocity at each frequency using the reference velocity and Q within the effective frequency range;

[0098] A response calculation module that calculates the spherical wave response at each frequency;

[0099] A product calculation module that then calculates the product of the spherical wave response and the seismic wavelet spectrum within the effective frequency range;

[0100] A wave field simulation module that calculates the inverse Fourier transform of the above product to obtain the time-domain seismic reflection wave field and incident wave field excited by the point source.

[0101] Example 5

[0102] An electronic device, the electronic device includes:

[0103] A memory that stores executable instructions;

[0104] A processor that runs the executable instructions in the memory to implement the point source seismic wave field simulation method, and the method includes:

[0105] Select the observation system parameters to be simulated and give a reference velocity;

[0106] Calculate the quality factor Q using the seismic data near the wellbore;

[0107] Calculate the spectrum of the seismic data to determine the effective frequency range of the seismic data;

[0108] Calculate the velocity at each frequency using the reference velocity and Q within the effective frequency range;

[0109] Calculate the spherical wave response at each frequency;

[0110] Then calculate the product of the spherical wave response and the seismic wavelet spectrum within the effective frequency range;

[0111] Calculate the inverse Fourier transform of the above product to obtain the time-domain seismic reflection wave field and incident wave field excited by the point source.

[0112] Example Six

[0113] This embodiment provides a non-transitory computer-readable storage medium storing a computer program, which, when executed by a processor, implements the above-described point-source seismic wave field simulation method, and the method includes:

[0114] Select the observation system parameters to be simulated and give a reference velocity;

[0115] Calculate the quality factor Q using the seismic data near the wellbore;

[0116] Calculate the spectrum of the seismic data to determine the effective frequency range of the seismic data;

[0117] Calculate the velocity at each frequency using the reference velocity and Q within the effective frequency range;

[0118] Calculate the spherical wave response at each frequency;

[0119] Then calculate the product of the spherical wave response and the seismic wavelet spectrum within the effective frequency range;

[0120] Calculate the inverse Fourier transform of the above product to obtain the time-domain seismic reflection wave field and incident wave field excited by the point source.

[0121] The above computer-readable storage medium includes but is not limited to: optical storage media (e.g., CD-ROM and DVD), magneto-optical storage media (e.g., MO), magnetic storage media (e.g., magnetic tape or external hard drive), media with built-in rewritable non-volatile memory (e.g., memory card), and media with built-in ROM (e.g., ROM cartridge).

[0122] In summary, the present invention proposes a point-source seismic wave field simulation method, which can be used for seismic wave field simulation and wave field characteristic research and analysis, enhance the understanding of the propagation law of the seismic wave field, and guide the acquisition, processing, and interpretation of seismic exploration, etc.

[0123] The embodiments of the present invention have been described above. The above description is exemplary and not exhaustive, and is also not limited to the disclosed embodiments. Many modifications and variations will be obvious to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A method for simulating the seismic wave field of a point source, characterized in that, it includes: Select the observation system parameters to be simulated and give a reference velocity; Calculate the quality factor Q using the seismic data of the well-side trace; Calculate the spectrum of the seismic data and determine the effective frequency range of the seismic data; Calculate the velocity at each frequency using the reference velocity and Q within the effective frequency range; Calculate the spherical wave response at each frequency; Then calculate the product of the spherical wave response and the seismic wavelet spectrum within the effective frequency range; Calculate the inverse Fourier transform of the above product to obtain the time-domain seismic reflection wave field and incident wave field excited by the point source.

2. The method for simulating the seismic wave field of a point source according to claim 1, characterized in that, The given reference velocity includes the reference velocities c 1ref and c 2ref of the longitudinal wave velocities of the upper and lower media given according to the simulation requirements.

3. The method for simulating the seismic wave field of a point source according to claim 1, characterized in that, Calculate the quality factor Q using the spectral ratio method based on the well-side seismic data.

4. The method for simulating the seismic wave field of a point source according to claim 1, characterized in that, Determine the effective frequency range of the seismic data as f1 to f2, and the main frequency as fp; Within the frequency range f1 to f2, calculate the velocity c(f) corresponding to each frequency according to the following formula: where f is the frequency, and c ref is the reference speed, f ref is the reference frequency, which may be the main frequency, and i is the imaginary unit.

5. The method for simulating the seismic wave field of a point source according to claim 4, characterized in that, Calculate the spherical reflection wave response \(P\) at each frequency according to the following formula ref (f): Among them, is the plane wave reflection coefficient, ρ 1 , ρ 2 are the densities of the upper and lower media respectively, c 1 (f), c 2 (f) are the longitudinal wave velocities of the upper and lower media respectively, θ is the incident angle, ω is the angular frequency and ω = 2πf, r is the offset, R is the propagation distance from the source to the receiver and R = r / sinθ, t is the propagation time; removing the B(θ) term in the above formula gives the spherical incident wave response at each frequency.

6. The method for simulating the seismic wave field of a point source according to claim 5, characterized in that, Calculating the product of the spherical wave response and the seismic wavelet spectrum includes: Select the wavelet used for forward simulation, and then calculate its spectrum, denoted as W(f); Calculate the reflected wavefield S in the frequency domain according to the following formula refl (f): S refl S(f) = W(f)P ref (f).

7. The method for simulating the seismic wave field of a point source according to claim 6, characterized in that, Calculate the inverse Fourier transform of the reflection wave field in the frequency domain to obtain the time-domain reflection wave field excited by the point source; remove the B(θ) term in the above formula to obtain the time-domain incident wave field excited by the point source.

8. A device for simulating the seismic wave field of a point source, characterized in that, it includes: A given velocity module that selects the observation system parameters to be simulated and gives a reference velocity; A factor calculation module that calculates the quality factor Q using the seismic data of the well-side trace; A frequency determination module that calculates the spectrum of the seismic data and determines the effective frequency range of the seismic data; A velocity calculation module that calculates the velocity at each frequency using the reference velocity and Q within the effective frequency range; A response calculation module that calculates the spherical wave response at each frequency; A product calculation module that then calculates the product of the spherical wave response and the seismic wavelet spectrum within the effective frequency range; A wave field simulation module that calculates the inverse Fourier transform of the above product to obtain the time-domain seismic reflection wave field and incident wave field excited by the point source.

9. An electronic device, characterized in that, the electronic device includes: A memory that stores executable instructions; A processor that runs the executable instructions in the memory to implement the method for simulating the seismic wave field of a point source according to any one of claims 1-7.

10. A non-transitory computer-readable storage medium, on which a computer program is stored, characterized in that, when the computer program is executed by a processor, it implements the method for simulating the seismic wave field of a point source according to any one of claims 1-7.

Images