A method for reconstructing VSP data into ground seismic data

Abstract

This invention relates to the field of exploration geophysics and provides a method for reconstructing VSP data into ground seismic data. This method can reconstruct VSP data into ground seismic data, changing the type of the original seismic data. The reconstructed seismic data has a high signal-to-noise ratio. Furthermore, by performing joint data processing on the original VSP data and the reconstructed ground seismic data, the imaging accuracy of underground geological structures can be improved, and the imaging range of underground geological structures can be effectively expanded, resulting in high-quality imaging results.

Description

Technical Field

[0001] This invention belongs to the field of exploration geophysics, and in particular relates to a method for reconstructing VSP data into ground seismic data. Background Technology

[0002] In the field of exploration geophysics, compared with conventional surface seismic exploration where both the source and detector are located on the surface, VSP seismic exploration places the detector in the well, closer to the subsurface geological target. This allows for more obvious and direct observation of the kinematic and dynamic characteristics of waves, and it can potentially avoid the influence of low-velocity zones near the surface, which is beneficial for detecting weak wave signals. It also provides higher imaging accuracy for structures near the well. Due to its many advantages, VSP is widely used in seismic exploration.

[0003] However, compared to conventional surface seismic exploration, VSP data has a limited imaging range, confined to a certain area near the well. To effectively expand the imaging range of subsurface geological structures, wavefield reconstruction can be used to change the data type of seismic data, reconstructing VSP data into surface seismic data, and then imaging it using surface seismic data processing procedures. After this wavefield reconstruction, the imaging range of subsurface geological structures is the same as that of surface seismic exploration with the same source coverage, significantly expanding the imaging range compared to standard VSP data. Furthermore, since actual seismic data is often affected by random noise, a method with strong noise resistance is needed to reconstruct VSP data into surface seismic data to obtain high-quality wavefield reconstruction data. Summary of the Invention

[0004] The purpose of this invention is to provide a method for reconstructing VSP data into ground seismic data, aiming to solve the problems mentioned in the background art.

[0005] This invention is implemented as follows: a method for reconstructing VSP data into ground seismic data includes the following steps:

[0006] Step 1: Extract the direct wave field from the VSP shot gather record, denoted as d, and the remaining wave field part as g;

[0007] Step 2: Take the direct wave field d at the i-th virtual vibration source point as the shot collection wave field. i Transforming to the τ-p domain using the Radon transform, its expression in the frequency domain is:

[0008] u d (p|x i ,ω)=∫d(x|x i ,ω)exp(iωpx)dx

[0009] Where d(x|x i ,ω) represents the original direct wave data, u d (p|x i (,ω) represents the Radon transform data, where ω is the angular frequency and x is the angular frequency. i The location of the earthquake source is represented by p, which is the ray parameter.

[0010] Step 3, from u d (p|x i Extract the positive value part of the ray parameter from ω, and represent it as: Extract the negative part of the ray parameter, and represent it as

[0011] Step 4: Take the residual wave field g, which is the shot at the i-th virtual source point, as the source point. i Transformed into the τ-p domain using the Radon transform;

[0012] Step 5, from u g (p|x i Extract the positive value part of the ray parameter from ω, and represent it as: Extract the negative part of the ray parameter, and represent it as

[0013] Step 6: Measure the direct wave field d at the j-th ground reference receiver point. j Transformed into the τ-p domain using the Radon transform;

[0014] Step 7, from u d (p|x j Extract the positive value part of the ray parameter from ω, and represent it as: Extract the negative part of the ray parameter, and represent it as

[0015] Step 8: Take the residual wave field g of the shot gather at the j-th ground reference receiver point. j Transformed into the τ-p domain using the Radon transform;

[0016] Step 9, from u g (p|x j Extract the positive value part of the ray parameter from ω, and represent it as: Extract the negative part of the ray parameter, and represent it as

[0017] Step 10: When the virtual source point i and the reference detector point j are located on the same side of the well, the virtual source point i is located at... Wavefield data and at the j-th reference receiver Cross-correlation and superposition operations are performed on the wavefield data to obtain the reconstructed ground seismic gather v(x) of the j-th trace from the i-th virtual source. j |xi The formula for calculating ω is:

[0018]

[0019] Step 11: When the virtual source point i and the reference detector point j are located on opposite sides of the well, the virtual source point i is located at... Wavefield data and at the j-th reference receiver Wavefield data are convolutional and superimposed to obtain the reconstructed ground seismic gather v(x) of the j-th trace from the i-th virtual source. j |x i The formula for calculating ω is:

[0020]

[0021] Step 12: Repeat steps 6 to 11 for all reference receiver points j to obtain the reconstructed ground seismic shot gather data of the i-th virtual source.

[0022] Step 13: Repeat steps 2 to 12 for all virtual seismic sources i to obtain all reconstructed ground seismic data.

[0023] A further technical solution is that, in step 4, the residual wave field g i The expression in the frequency domain after Radon transform is: u g (p|x i ,ω)=∫g(x|x i ,ω)exp(iωpx)dx.

[0024] A further technical solution is that, in step 6, the direct wave field d j The expression in the frequency domain after Radon transform is: u d (p|x j ,ω)=∫d(x|x j ,ω)exp(iωpx)dx.

[0025] A further technical solution is that, in step 8, the residual wave field g j The expression in the frequency domain after Radon transform is: u g (p|x j ,ω)=∫g(x|x j ,ω)exp(iωpx)dx.

[0026] This invention provides a method for reconstructing VSP data into ground seismic data. Through wavefield reconstruction, the original VSP shot gather data is reconstructed into ground seismic shot gather data, expanding the data type of the original seismic data. In subsequent seismic data processing, the original VSP data and the reconstructed ground seismic data can be processed together, effectively utilizing the complementary advantages of the processing results of the two data types to improve the imaging quality and accuracy of seismic data processing. Attached Figure Description

[0027] Figure 1 A geological model diagram is provided in an embodiment of the present invention for a method of reconstructing VSP data into ground seismic data.

[0028] Figure 2 This is a VSP shot gather data map provided in an embodiment of the present invention for a method of reconstructing VSP data into ground seismic data;

[0029] Figure 3 This is a direct wave field data map extracted from VSP shot gather data in a method for reconstructing VSP data into ground seismic data provided in an embodiment of the present invention;

[0030] Figure 4 The residual wave field data map is extracted from VSP shot gather data in a method for reconstructing VSP data into ground seismic data provided in an embodiment of the present invention;

[0031] Figure 5 This invention provides a method for reconstructing VSP data into ground seismic data, specifically a method for reconstructing ground seismic shot gather data. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0033] The specific implementation of the present invention will be described in detail below with reference to specific embodiments.

[0034] A method for reconstructing VSP data into ground seismic data according to an embodiment of the present invention includes the following steps:

[0035] Step 1: Extract the direct wave field from the VSP shot gather record, denoted as d, and the remaining wave field part as g;

[0036] Step 2: Take the direct wave field d at the i-th virtual vibration source point as the shot collection wave field. i Transforming to the τ-p domain using the Radon transform, its expression in the frequency domain is:

[0037] u d (p|x i ,ω)=∫d(x|x i ,ω)exp(iωpx)dx

[0038] Where d(x|x i ,ω) represents the original direct wave data, u d (p|x i (,ω) represents the Radon transform data, where ω is the angular frequency and x is the angular frequency. i The location of the earthquake source is represented by p, which is the ray parameter.

[0039] Step 3, from u d (p|x i Extract the positive value part of the ray parameter from ω, and represent it as: Extract the negative part of the ray parameter, and represent it as

[0040] Step 4: Take the residual wave field g, which is the shot at the i-th virtual source point, as the source point. i Transforming to the τ-p domain using the Radon transform, its expression in the frequency domain is:

[0041] u g (p|x i ,ω)=∫g(x|x i ,ω)exp(iωpx)dx;

[0042] Step 5, from u g (p|x i Extract the positive value part of the ray parameter from ω, and represent it as: Extract the negative part of the ray parameter, and represent it as

[0043] Step 6: Measure the direct wave field d at the j-th ground reference receiver point. j Transforming to the τ-p domain using the Radon transform, its expression in the frequency domain is:

[0044] u d (p|x j ,ω)=∫d(x|x j ,ω)exp(iωpx)dx;

[0045] Step 7, from u d (p|x j Extract the positive value part of the ray parameter from ω, and represent it as: Extract the negative part of the ray parameter, and represent it as

[0046] Step 8: Take the residual wave field g of the shot gather at the j-th ground reference receiver point. j Transforming to the τ-p domain using the Radon transform, its expression in the frequency domain is:

[0047] u g (p|x j ,ω)=∫g(x|x j ,ω)exp(iωpx)dx;

[0048] Step 9, from u g (p|x j Extract the positive value part of the ray parameter from ω, and represent it as: Extract the negative part of the ray parameter, and represent it as

[0049] Step 10: When the virtual source point i and the reference detector point j are located on the same side of the well, the virtual source point i is located at... Wavefield data and at the j-th reference receiver Cross-correlation and superposition operations are performed on the wavefield data to obtain the reconstructed ground seismic gather v(x) of the j-th trace from the i-th virtual source. j |x i The formula for calculating ω is:

[0050]

[0051] Step 11: When the virtual source point i and the reference detector point j are located on opposite sides of the well, the virtual source point i is located at... Wavefield data and at the j-th reference receiver Wavefield data are convolutional and superimposed to obtain the reconstructed ground seismic gather v(x) of the j-th trace from the i-th virtual source. j |x i The formula for calculating ω is:

[0052]

[0053] Step 12: Repeat steps 6 to 11 for all reference receiver points j to obtain the reconstructed ground seismic shot gather data of the i-th virtual source.

[0054] Step 13: Repeat steps 2 to 12 for all virtual seismic sources i to obtain all reconstructed ground seismic data.

[0055] In this embodiment of the invention, for Figure 1 The geological model shown yields the following results: Figure 2 The VSP shot gather data shown, after applying this method, Figure 3 and Figure 4These are the direct wave field data and residual wave field data extracted from the VSP shot gather data, respectively. Figure 5 This is reconstructed ground seismic shot gather data. Therefore, for VSP seismic data, the method of this invention for reconstructing VSP data into ground seismic data can change the data type of the original seismic data and reconstruct VSP data into ground seismic data.

[0056] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method of VSP data reconstruction to surface seismic data, characterized in that, The method comprises the following steps: Step 1, extracting the direct wave wave field from the VSP shot record, denoted as d, and the residual wave field part denoted as g; Step 2, calculate the direct wave field d at the i-th virtual shot point as the i-th shot gather i The Radon transform is used to convert to the τ-p domain, whose expression in the frequency domain is: u d (p|x i ,ω) = ∫ d(x|x i ,ω) exp(iωpx) dx; where d(x | x i , ω) represents the original direct wave data, u d (p | x i , ω) represents the data after Radon transform, ω is the angular frequency, x i represents the source position, and p is the ray parameter; Step 3, extract the positive part of the ray parameter from u d (p|x i ,ω) as extract the negative part of the ray parameter as Step 4, convert the residual wavefield g as shot gather at the ith virtual source point to the τ-p domain by Radon transform i Step 4, convert the residual wavefield g as shot gather at the ith virtual source point to the τ-p domain by Radon transform Step 5, extract the positive part of the ray parameter from u g (p|x i ,ω) as extract the negative part of the ray parameter as Step 6, convert the direct wave field d as the jth shot gather at the ground reference receiver point to the τ-p domain by Radon transform j by Radon transform to the τ-p domain; Step 7, extract the positive part of the ray parameter from u d (p|x j ,ω) as extract the negative part of the ray parameter as Step 8, convert the residual wavefield g as the jth shot gather at the ground reference receiver point to the τ-p domain by Radon transform j by Radon transform to the τ-p domain; Step 9, extract the positive part of the ray parameter from u g (p|x j ,ω) as extract the negative part of the ray parameter as Step 10, when the virtual source point i and the reference receiver point j are located on the same side of the well, the wave field data at the i-th virtual source point and the wave field data at the j-th reference receiver point are cross-correlated and stacked to obtain the i-th virtual source j-th channel reconstructed ground seismic trace v(x . Step 11, the i-th virtual source j-th channel reconstructed ground seismic trace v(x j |x i ,ω) is obtained, and the calculation formula is as follows: Step 11, when the virtual source point i and the reference receiver point j are located on both sides of the well, the wave field data at the i-th virtual source point and the wave field data at the j-th reference receiver point are folded and stacked to obtain the reconstructed ground seismic trace set v(x |ω) of the i-th virtual source j-th trace, and the calculation formula is: j i |ω) of the i-th virtual source j-th trace, and the calculation formula is:​​ Step 12, repeating steps 6 to 11 for all reference geophones j to obtain the reconstructed ground seismic shot data of the i-th virtual source; Step 13, repeating steps 2 to 12 for all virtual sources i to obtain all reconstructed ground seismic data.

2. The method of VSP data reconstruction to surface seismic data of claim 1, wherein, In said step 4, the remaining wavefield g i After Radon transform, the expression in the frequency domain is: u g (p|x i ,ω) = ∫g(x|x i ,ω) exp(iωpx) dx.

3. The method of VSP data reconstruction to surface seismic data of claim 1, wherein, In the step 6, the direct wave wavefield d j After Radon transform, the expression in the frequency domain is: d (p|x j ,ω) = ∫d(x|x j ,ω)exp(iωpx)dx.

4. The method of VSP data reconstruction to surface seismic data of claim 1, wherein, In said step 8, the remaining wavefield g j After Radon transform, the expression in the frequency domain is: u g (p|x j ,ω) = ∫g(x|x j ,ω) exp(iωpx) dx.

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