Denoising method for seismic data signal based on variational principle

A technology based on seismic data and variational principles, applied in the field of petroleum exploration, can solve problems such as the inability to achieve the efficiency and stability of seismic signal measurement operations, susceptibility to noise, and unstable results, and achieve the shortest path robustness and wide application value , the effect of suppressing the interference of noise

Pending Publication Date: 2019-06-21
CHINA PETROLEUM & CHEM CORP +1
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Problems solved by technology

[0010] The traditional DTW method needs to find the shortest path through two steps of accumulation and backtracking, which can extract the nonlinear time shift, but it has a large amount of calculation and is easily affected by noise, falling into local extremum, making the result unstable
[0011] These methods have their own advantages and disadvantages, but they still cannot meet people's needs for the efficiency and stability of seismic signal measurement operations.

Method used

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  • Denoising method for seismic data signal based on variational principle
  • Denoising method for seismic data signal based on variational principle
  • Denoising method for seismic data signal based on variational principle

Examples

Experimental program
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Embodiment 1

[0097] 1: Input two segments of seismic data (such as image 3 shown), where A on the left is the reference signal, and B on the right is the test signal.

[0098] 2: Construct difference matrix (such as Figure 4a ), and transform it into a slowness matrix (as Figure 4b shown).

[0099] 3: Extract the shortest path, (such as Figure 5a , Figure 5b shown), where the path calculated from the start node to the end node does not agree with the curve of the path obtained from the end node to the start node, extracting the boundary in the same path ( Figure 5a A-F six points), re-do the shortest path ray tracing, and finally get the shortest path such as Figure 5b shown.

[0100] 4: Apply the travel time shift of each sampling point corresponding to the obtained shortest path to the test signal to obtain an updated signal (such as Image 6 shown).

[0101] From the analysis, it can be found that both the backward time-shifted seismic wavelet and the forward time-shifted...

Embodiment 2

[0103] This method is applied to the optimal stacking and denoising process of actual pre-stack seismic data.

[0104] 1: First, the shot trace set is divided into several small areas, and in each small area, the reference trace is obtained by superimposing all the traces.

[0105] 2: In each small area, calculate the shortest path between all the seismic traces and the reference trace, obtain the time-shift disturbance, and obtain the updated seismic trace. The estimation process is the same as that of Experiment 1.

[0106] 3: Finally, the updated stacks are stacked in each region to achieve denoising of the pre-stack seismic data.

[0107] in Figure 7a is the pass set before processing, Figure 7b is the processed shot pass set. It can be seen that the original shot set contains more coherent noise, and the deep events are covered by the noise and cannot be identified. After processing, the noise is effectively removed, whether it is shallow or deep, the continuity of...

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Abstract

The invention discloses a denoising method for a seismic data signal based on a variational principle. The method includes the following steps: S1. inputting a test signal f and a reference signal g in a seismic signal processing model and selecting a sampling point; S2. performing normalization processing on the test signal and the reference signal to construct a difference matrix; S3. convertingthe difference matrix to a slowness matrix; S4. based on a Fermat principle and Huygens-Fresnel principle, extracting global minimum travel time and a corresponding shortest path in the slowness matrix by utilizing a minimum path ray tracing method; and S5. applying time shift amount of the travel time of each of sampling points in the obtained shortest path to the test signal to obtain the denoised seismic data signal. The method is modified from two aspects of a theory and implementation, the computational efficiency is improved, the stability of finding the shortest path is enhanced, and anew perspective is opened for measurement of nonlinear signals.

Description

technical field [0001] The invention relates to the field of petroleum exploration, in particular to a method for denoising seismic data signals based on variational principles. Background technique [0002] There are not many methods for seismic signal measurement and each has its own advantages and disadvantages. Currently, the nonlinear difference measurement techniques for estimating seismic signals are as follows: [0003] 1. Cross-correlation method [0004] The method uses the stationarity of the random signal to calculate the cross-correlation between two signals, and determines the time-shift of the signal by extracting the maximum value of the cross-correlation. This method is only suitable for stationary signals and has a large amount of calculation. [0005] 2. Polynomial fitting method [0006] This method assumes that the time difference of the seismic signal in the local neighborhood track conforms to an undetermined polynomial, and extracts different time ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01V1/36
Inventor 葛大明梁鸿贤王延光王常波高丽孔青华揭景荣
Owner CHINA PETROLEUM & CHEM CORP
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