Post-stack wave impedance inversion method and device based on multi-channel joint inversion

Abstract

The invention relates to the technical field of oil and gas field seismic exploration and development, and discloses a post-stack wave impedance inversion method and device based on multichannel joint inversion, and the method comprises the steps: constructing a wave impedance parameter solving expression; establishing a multi-channel joint inversion wave impedance parameter solution expression according to the coupling correlation of the impedance parameter solution expression and adjacent seismic channel parameters; and determining iteration initial input according to seismic structure interpretation data and logging data, and performing iteration updating on the multi-channel joint inversion wave impedance parameter solution expression. According to the post-stack wave impedance inversion method, the generalized nonlinear inversion algorithm is introduced into post-stack wave impedance inversion, generation of indirect calculation accumulative errors is effectively avoided, the space coupling correlation of adjacent seismic channel sets is fully considered, a multi-channel joint inversion equation set is established, multi-seismic-channel joint constraint is formed, and the method has the advantages of being high in reliability and high in reliability. And the precision, the transverse continuity and the resolution of a wave impedance inversion result are effectively improved.

Description

Technical Field

[0001] The invention relates to the technical field of oil and gas field seismic exploration and development, and in particular to a post-stack wave impedance inversion method and device based on multi-channel joint inversion. Background Art

[0002] For the actual exploration and development areas of most oil fields, post-stack wave impedance inversion is still an important geophysical technology for reservoir characterization. Reliable wave impedance prediction results help improve the success rate of exploration and reduce investment costs. Although post-stack wave impedance inversion has undergone years of development and related methods and technologies have become relatively mature, there are still many problems, such as cumulative errors in recursive inversion, ill-posedness of inverse problems, and insufficient lateral constraints. Denis and William (1983) proposed a generalized linear inversion method based on seismic wave data, which effectively alleviated the impact of cumulative errors. Geng Weiheng et al. (2022) linearized the post-stack wave impedance reflection coefficient formula based on a discretization method, cleverly avoiding the occurrence of cumulative errors. In order to completely solve the ill-posedness problem of the inverse problem, a large number of scholars have carried out post-stack wave impedance inversion based on the damped least squares algorithm. In fact, whether it is the problem of cumulative error or ill-posedness, it ultimately affects the vertical accuracy of the wave impedance prediction results. At present, scholars have conducted a lot of research on how to improve the vertical accuracy and resolution of wave impedance prediction results. The wave impedance inversion results based on single seismic data can not only effectively identify reservoirs but also well characterize reservoir boundaries. In order to improve the lateral continuity of wave impedance inversion results, Liao Jianping et al. (2018) introduced thin interbed model constraints, which effectively improved the lateral continuity of inversion results. This method requires the construction of a high-resolution thin interbed model, which usually cannot meet the model construction requirements for complex reservoirs, greatly limiting the use of this method.

[0003] The conventional wave impedance inversion method in the above-mentioned technologies focuses more on how to improve the vertical accuracy and resolution of the inversion results, while ignoring the importance of the lateral continuity and resolution of the inversion results. In particular, in the inversion process, the single-channel inversion method is mainly used, or a method similar to the joint inversion based on the pre-stack angle gather is used to simply use multi-channel seismic data as a joint input, without considering the coupling correlation between adjacent seismic channels. Summary of the invention

[0004] The present invention aims to solve at least one of the technical problems in the above-mentioned technology to a certain extent. To this end, the present invention proposes a post-stack wave impedance inversion method based on multi-channel joint inversion, comprising:

[0005] Construct the wave impedance parameter solution expression;

[0006] According to the impedance parameter solution expression and the coupling correlation of adjacent seismic trace parameters, a multi-channel joint inversion wave impedance parameter solution expression is established;

[0007] The initial input of the iteration is determined according to the seismic structure interpretation data and the logging data, and the expression for solving the multi-channel joint inversion wave impedance parameters is iteratively updated.

[0008] Preferably, the wave impedance parameter solution expression includes:

[0009] AZ=b

[0010] Where A=H T H+αE; b=H T D+αμ; E represents the identity matrix; α represents the ratio of the wave impedance parameter variance to the noise variance; D = df(Z 0 )+HZ 0 , f(Z 0 ) is the first term of the Taylor series expansion of d, d=f(Z)+n, d represents the observed seismic data, f(Z) represents the function of the seismic signal with respect to the wave impedance Z, n represents the noise; μ is the mean vector of the wave impedance parameters.

[0011] Preferably, according to the solution expression of the impedance parameter and the coupling correlation of the adjacent seismic trace parameters, a solution expression of the multi-channel joint inversion wave impedance parameter is established, including:

[0012] The current seismic trace is regarded as the result of the displacement of the previous seismic trace, and the wave impedance parameter solution expression of the current seismic trace is constructed based on the wave impedance parameter solution expression of the previous seismic trace; the above method is repeated to construct the wave impedance parameter solution expression of each seismic trace;

[0013] The wave impedance parameter solution expressions of all seismic channels are combined to obtain the wave impedance parameter solution expression of the multi-channel joint inversion.

[0014] Preferably, the multi-channel joint inversion wave impedance parameter solution expression includes:

[0015]

[0016] Among them, A n Z n =A n Z1+A n ΔZ1+…+A n ΔZ n-1 =b n ; Z1 is the equivalent linear forward equation of the formation parameters corresponding to the first seismic channel; A n ΔZ n-1Indicates that the nth seismic trace is the result of spatial displacement of the n-1th seismic trace; A n is the linear forward operator corresponding to the nth seismic trace.

[0017] The second aspect of the present invention provides a post-stack wave impedance inversion system based on multi-channel joint inversion, comprising:

[0018] The first building module is used to build a solution expression for wave impedance parameters;

[0019] The second building module is used to establish a multi-channel joint inversion wave impedance parameter solution expression according to the impedance parameter solution expression and the coupling correlation of adjacent seismic channel parameters;

[0020] The iterative solution module is used to determine the initial input of the iteration according to the seismic structure interpretation data and the logging data, and iteratively update the expression for solving the multi-channel joint inversion wave impedance parameters.

[0021] Preferably, the wave impedance parameter solution expression constructed by the first building block includes:

[0022] AZ=b

[0023] Where A=H T H+αE; b=H T D+αμ; E represents the identity matrix; α represents the ratio of the wave impedance parameter variance to the noise variance; D = df(Z 0 )+HZ 0 , f(Z 0 ) is the first term of the Taylor series expansion of d, d=f(Z)+n, d represents the observed seismic data, f(Z) represents the function of the seismic signal with respect to the wave impedance Z, n represents the noise; μ is the mean vector of the wave impedance parameters.

[0024] Preferably, the method performed by the second building block includes:

[0025] The current seismic trace is regarded as the result of the displacement of the previous seismic trace, and the wave impedance parameter solution expression of the current seismic trace is constructed based on the wave impedance parameter solution expression of the previous seismic trace; the above method is repeated to construct the wave impedance parameter solution expression of each seismic trace;

[0026] The wave impedance parameter solution expressions of all seismic channels are combined to obtain the wave impedance parameter solution expression of the multi-channel joint inversion.

[0027] Preferably, the multi-channel joint inversion wave impedance parameter solution expression constructed by the second construction module includes:

[0028]

[0029] Among them, A n Z n =A n Z1+A n ΔZ1+…+A n ΔZ n-1 =b n ; Z1 is the equivalent linear forward equation of the formation parameters corresponding to the first seismic channel; A n ΔZ n-1 Indicates that the nth seismic trace is the result of spatial displacement of the n-1th seismic trace; A n is the linear forward operator corresponding to the nth seismic trace.

[0030] A third aspect of the present invention proposes an electronic device, comprising a memory and a processor, wherein the memory stores a computer program or instruction, and when the computer program or instruction is executed by the processor, it is at least used to implement the above-mentioned post-stack wave impedance inversion method based on multi-channel joint inversion.

[0031] A fourth aspect of the present invention provides a computer-readable storage medium, in which a computer program or instruction is stored. When the computer program or instruction is executed by a processor, it is at least used to implement the above-mentioned post-stack wave impedance inversion method based on multi-channel joint inversion.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] The present invention introduces a generalized nonlinear inversion algorithm into post-stack wave impedance inversion, effectively avoiding the generation of indirect calculation cumulative errors. The present invention fully considers the spatial coupling correlation of adjacent seismic trace sets, and thereby establishes a multi-channel joint inversion equation group to form multi-channel joint constraints, overcoming the defect of traditional multi-channel joint inversion that simply combines seismic traces, and effectively improving the accuracy, lateral continuity and resolution of wave impedance inversion results.

[0034] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description and the accompanying drawings.

[0035] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0037] Figure 1 A schematic diagram of a post-stack wave impedance inversion method based on multi-channel joint inversion provided in an embodiment;

[0038] Figure 2 A schematic diagram of actual field post-stack seismic data provided in an embodiment;

[0039] Figure 3 A schematic diagram of wave impedance inversion results provided in an embodiment;

[0040] Figure 4 A schematic diagram of the wave impedance inversion result of the traditional method given in the embodiment;

[0041] Figure 5 A comparison diagram of the inversion logging curve and the actual logging curve given in the embodiment;

[0042] Figure 6 A schematic diagram of a post-stack wave impedance inversion system based on multi-channel joint inversion is provided in an embodiment;

[0043] Figure 7 A schematic diagram of an electronic device provided for an embodiment;

[0044] Figure 8 A schematic diagram of a computer-readable storage medium is provided for an embodiment. DETAILED DESCRIPTION

[0045] The present invention is described below in conjunction with the accompanying drawings. The preferred embodiments described herein are only used to illustrate and explain the present invention and are not used to limit the present invention.

[0046] Figure 1 The post-stack wave impedance inversion method based on multi-channel joint inversion provided by the present invention comprises:

[0047] S101. Constructing wave impedance parameter solution expression;

[0048] S102. Establishing a multi-channel joint inversion wave impedance parameter solution expression based on the impedance parameter solution expression and the coupling correlation of adjacent seismic trace parameters;

[0049] S103. Determine the initial input of the iteration according to the seismic structure interpretation data and the logging data, and iteratively update the expression for solving the multi-channel joint inversion wave impedance parameters.

[0050] According to some embodiments of the present invention, constructing a wave impedance parameter solution expression includes:

[0051] (1) Seismic wavelets are extracted based on post-stack seismic data, and then the amplitude scaling factor is determined by comparing the well-side channel forward modeling seismic records with the actual seismic records: First, seismic wavelets are extracted using post-stack seismic data, and then the seismic wavelets are convolved with the reflection coefficient sequence based on the logging data to obtain the well-side channel synthetic seismic records, which are finally compared with the actual well-side channel seismic records to obtain the amplitude scaling factor and verify the rationality of the seismic wavelets.

[0052] (2) Using the seismic structural interpretation data (information such as strata and faults) and all the well logging data in the work area, an initial wave impedance parameter model in the time domain is established based on the sedimentary model: Using the seismic structural interpretation data, a geological model is established based on the sedimentary model, and the well logging data is interpolated and extrapolated according to the structural model to obtain the initial wave impedance parameter model for each survey line.

[0053] (3) Based on the generalized nonlinear inversion theory, the deterministic inversion solution expression of post-stack wave impedance based on a single seismic trace is derived: the nonlinear inversion objective function of post-stack wave impedance is constructed based on the Bayesian theory, and the nonlinear inversion objective function is solved with the help of Taylor series expansion, and finally the solution expression of wave impedance parameters is obtained. In this process, based on the convolution model, the forward equation of post-stack seismic data can be expressed as:

[0054] d = f(Z) + n, d represents the observed seismic data, f(Z) represents the function of the seismic signal with respect to the wave impedance Z, and n represents the noise. The generalized nonlinear post-stack wave impedance inversion process based on Bayesian theory includes: Assuming that the noise data obeys the Gaussian distribution and the wave impedance parameters also obey the Gaussian distribution, the posterior probability distribution function shown below can be obtained:

[0055]

[0056] Among them, P(Z|d) is the posterior probability distribution function, represents the noise variance, represents the variance of the wave impedance parameter, and μ is the mean vector of the wave impedance parameter. The problem of solving the maximum a posteriori probability solution of the above equation can be transformed into solving This objective function minimization problem:

[0057] By performing Taylor series expansion on d=f(Z)+n, we can obtain:

[0058]

[0059] Pick The first-order approximation of and substituting it into the above objective function can obtain the following expression:

[0060]

[0061] make D = df(Z 0 )+HZ 0 , then:

[0062]

[0063] Taking the derivative of this formula with respect to the wave impedance parameter vector Z and setting the derivative to zero, we can obtain:

[0064] (H T H+αE)Z=H T D+αμ

[0065] Where E is the identity matrix. Let A = H T H+αE,b=H T D+αμ, then:

[0066] AZ=b

[0067] The generalized nonlinear wave impedance inversion based on a single seismic trace can be realized by using AZ=b.

[0068] According to some embodiments of the present invention, based on the coupling correlation of adjacent seismic trace parameters, a multi-channel joint inversion wave impedance parameter solution expression is established, including: AZ=b can be regarded as an equivalent linear forward equation with A as a linear forward operator, b as observed seismic data, and wave impedance Z as a formation parameter. The observed seismic data of the first channel can be expressed as:

[0069] A1Z1=b1

[0070] The seismic data observed in the seismic traces adjacent to the first trace can be expressed as

[0071] A2Z2=b2

[0072] The seismic traces adjacent to the first trace can be regarded as the result of a small spatial displacement of the first trace, which means that the wave impedance parameters corresponding to the adjacent seismic traces have the following relationship with the wave impedance parameters corresponding to the first trace:

[0073] Z2=Z1+ΔZ1

[0074] Substituting the above formula into A2Z2=b2, we can get:

[0075] A2Z2=A2(Z1+ΔZ1)=A2Z1+A2ΔZ1=b2

[0076] By analogy, along the survey line direction, the third channel of observed seismic data can be expressed as:

[0077] A3Z3=A3(Z2+ΔZ2)=A3Z1+A3ΔZ1+A3ΔZ2=b3

[0078] Extending the above situation to the nth channel, we have:

[0079] A n Z n =A n Z1+A n ΔZ1+…+A n ΔZ n-1 =b n

[0080] From the first to the nth equations, it can be seen that the n seismic data are all equations about Z1, so we can combine the forward equations corresponding to these n seismic data to form a set of equations for joint inversion of multi-channel seismic data, which is expressed as follows:

[0081]

[0082] Based on the above formula, post-stack wave impedance inversion based on multi-channel joint inversion can be realized:

[0083]

[0084] In the final solution expression, the matrix A and the vector b are both about the initial model Z 0 The initial model is used as input to obtain a set of wave impedance inversion results. Then, this set of wave impedance inversion results is used to calculate Z in the above formula. 0 Update, thus forming an iterative update solution process until the preset maximum number of iterations is reached.

[0085] Figure 2 The actual field post-stack observation seismic data given in the embodiment of the present invention, the grayscale represents the amplitude, the abscissa represents the CDP, i.e. the common depth point, and the ordinate represents the time. Figure 3 The wave impedance inversion result obtained according to the method given in the present invention is: Figure 3 The gray scale in the figure represents the wave impedance value, the horizontal axis represents CDP, and the vertical axis represents time. Figure 4 is the wave impedance inversion result obtained by the traditional method, Figure 4 The gray scale in the figure represents the wave impedance value, the horizontal axis represents CDP, and the vertical axis represents time. Figure 3 and Figure 4 It is not difficult to draw the following conclusion from the comparison: the inversion result obtained by the post-stack wave impedance inversion method based on multi-channel joint inversion given in this application has better lateral continuity and higher resolution. Figure 5It is a comparison diagram between the inverted logging curve and the actual logging curve, the ordinate represents time, the abscissa represents the wave impedance parameter, the solid line in the figure represents the actual logging curve, the dotted line represents the logging curve obtained by inversion through the traditional method, and the solid line with an asterisk represents the inverted logging curve obtained by the method provided by the present invention. By comparison, it is not difficult to draw the following conclusion: at the 2.2s target reservoir position, the inversion result obtained by the post-stack wave impedance inversion method based on multi-channel joint inversion provided in the present application, that is, the solid line with an asterisk is closer to the real logging curve, that is, the accuracy is higher, and the description of the reservoir is clearer.

[0086] Based on the same inventive concept, Figure 6 As shown, the present application proposes a post-stack wave impedance inversion system based on multi-channel joint inversion, including: a first construction module 201, used to construct a wave impedance parameter solution expression; a second construction module 202, used to establish a multi-channel joint inversion wave impedance parameter solution expression based on the impedance parameter solution expression and the coupling correlation of adjacent seismic channel parameters; an iterative solution module 203, used to determine the initial input of the iteration based on the seismic structure interpretation data and the logging data, and iteratively update the multi-channel joint inversion wave impedance parameter solution expression. Figure 7 As shown, the present application also provides an electronic device 1000, including a memory 1002 and a processor 1001, wherein the memory 1002 stores a computer program or instruction, and when the computer program or instruction is executed by the processor 1001, it is at least used to implement the above-mentioned post-stack wave impedance inversion method based on multi-channel joint inversion. Figure 8 As shown, the present application also provides a computer-readable storage medium 1100, in which a computer program or instruction is stored. When the computer program or instruction is executed by a processor, it is at least used to implement the above-mentioned post-stack wave impedance inversion method based on multi-channel joint inversion.

[0087] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A post-stack wave impedance inversion method based on multi-channel joint inversion, characterized in that: include: Construct the wave impedance parameter solution expression; According to the impedance parameter solution expression and the coupling correlation of adjacent seismic trace parameters, a multi-channel joint inversion wave impedance parameter solution expression is established; The initial input of the iteration is determined according to the seismic structure interpretation data and the logging data, and the expression for solving the multi-channel joint inversion wave impedance parameters is iteratively updated.

2. The post-stack wave impedance inversion method based on multi-channel joint inversion according to claim 1, characterized in that: The wave impedance parameter solution expression includes: AZ=b Where A=H T H+αE; b=H T D+αμ; E represents the identity matrix; α represents the ratio of the wave impedance parameter variance to the noise variance; D = df(Z 0 )+HZ 0 , f(Z 0 ) is the first term of the Taylor series expansion of d, d=f(Z)+n, d represents the observed seismic data, f(Z) represents the function of the seismic signal with respect to the wave impedance Z, n represents the noise; μ is the mean vector of the wave impedance parameters.

3. The post-stack wave impedance inversion method based on multi-channel joint inversion according to claim 2, characterized in that: According to the solution expression of the impedance parameter and the coupling correlation of adjacent seismic trace parameters, a solution expression of the multi-channel joint inversion wave impedance parameter is established, including: The current seismic trace is regarded as the result of the displacement of the previous seismic trace, and the wave impedance parameter solution expression of the current seismic trace is constructed based on the wave impedance parameter solution expression of the previous seismic trace; the above method is repeated to construct the wave impedance parameter solution expression of each seismic trace; The wave impedance parameter solution expressions of all seismic channels are combined to obtain the wave impedance parameter solution expression of the multi-channel joint inversion.

4. The post-stack wave impedance inversion method based on multi-channel joint inversion according to claim 3, characterized in that: The multi-channel joint inversion wave impedance parameter solution expression includes: Among them, A n Z n =A n Z1+A n ΔZ1+…+A n ΔZ n-1 =b n ; Z1 is the equivalent linear forward equation of the formation parameters corresponding to the first seismic channel; A n ΔZ n-1 Indicates that the nth seismic trace is the result of spatial displacement of the n-1th seismic trace; A n is the linear forward operator corresponding to the nth seismic trace.

5. A post-stack impedance inversion system based on multi-channel joint inversion, characterized in that: include: The first building module is used to build a solution expression for wave impedance parameters; The second building module is used to establish a multi-channel joint inversion wave impedance parameter solution expression according to the impedance parameter solution expression and the coupling correlation of adjacent seismic channel parameters; The iterative solution module is used to determine the initial input of the iteration according to the seismic structure interpretation data and the logging data, and iteratively update the expression for solving the multi-channel joint inversion wave impedance parameters.

6. The post-stack wave impedance inversion system based on multi-channel joint inversion according to claim 5, characterized in that: The wave impedance parameter solution expression constructed by the first building block includes: AZ=b Where A=H T H+αE; b=H T D+αμ; E represents the identity matrix; α represents the ratio of the wave impedance parameter variance to the noise variance; D = df(Z 0 )+HZ 0 , f(Z 0 ) is the first term of the Taylor series expansion of d, d=f(Z)+n, d represents the observed seismic data, f(Z) represents the function of the seismic signal with respect to the wave impedance Z, n represents the noise; μ is the mean vector of the wave impedance parameters.

7. The post-stack wave impedance inversion system based on multi-channel joint inversion according to claim 6, characterized in that: The method executed by the second building block includes: The current seismic trace is regarded as the result of the displacement of the previous seismic trace, and the wave impedance parameter solution expression of the current seismic trace is constructed based on the wave impedance parameter solution expression of the previous seismic trace; the above method is repeated to construct the wave impedance parameter solution expression of each seismic trace; The wave impedance parameter solution expressions of all seismic channels are combined to obtain the wave impedance parameter solution expression of the multi-channel joint inversion.

8. The post-stack wave impedance inversion system based on multi-channel joint inversion according to claim 7, characterized in that: The second building block constructs the multi-channel joint inversion wave impedance parameter solution expression, including: Among them, A n Z n =A n Z1+A n ΔZ1+…+A n ΔZ n-1 =b n ; Z1 is the equivalent linear forward equation of the formation parameters corresponding to the first seismic channel; A n ΔZ n-1 Indicates that the nth seismic trace is the result of spatial displacement of the n-1th seismic trace; A n is the linear forward operator corresponding to the nth seismic trace.

9. An electronic device, characterized in that: It comprises a memory and a processor, wherein the memory stores a computer program or instruction, and when the computer program or instruction is executed by the processor, it is at least used to implement the post-stack wave impedance inversion method based on multi-channel joint inversion as described in any one of claims 1-4.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program or instruction, which, when executed by a processor, is at least used to implement the post-stack wave impedance inversion method based on multi-channel joint inversion as described in any one of claims 1 to 4.

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