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Seismic coherence algorithm based on wavelet transformation

A technology of wavelet transform and calculation method, applied in the field of oil and gas field exploration, can solve problems such as large errors and affecting application results

Inactive Publication Date: 2009-09-30
中国石油集团西北地质研究所有限公司
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  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the quality of the Hilbert transform is very important when calculating the coherent volume. This transform is very sensitive to noise. If the noise in the original seismic data is too large, the calculated Hilbert transform may have a large error, which will affect the application effect of K.J.Marfurt et al.

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  • Seismic coherence algorithm based on wavelet transformation

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Experimental program
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Effect test

Embodiment 1

[0108] The present invention includes the following steps:

[0109] Perform noise removal and spectrum preprocessing on the original seismic data obtained by field high-resolution seismic acquisition equipment using existing technology to improve the signal-to-noise ratio of seismic data and broaden the effective frequency bandwidth of seismic data;

[0110] 2. Perform fine spectrum analysis on the seismic data processed in step 1 to determine the effective spectrum range of the seismic data;

[0111] 3. Perform horizon interpretation on seismic data, and interpolate and smooth the picked seismic interpretation horizon;

[0112] 4. Take the seismic data and the interpreted seismic horizon as input, use the high-resolution derivative wavelet function to perform wavelet transformation on a certain seismic channel of the input seismic data to obtain the frequency division result of the wavelet transform; the derivative wavelet function is as in equation (1) :

[0113] ...

Embodiment 2

[0132] Example 2 Figures 2 (a)-4 (b) show the application of the invention in the Tangdong-Manan area of ​​Dagang Oilfield. The steps are the same as in Example 1.

[0133] Figure 2(a) shows the high-frequency coherence at the bottom of the Guantao Formation in Example 2. This result can well identify small faults; the figure clearly shows that there are two groups of main control oilfield structural faults, one group is represented by F1 The north-north-east-trending faults of F2; a group of West-West-East faults represented by F2. In the figure, A is a group of 4-5 faults. The NNE-trending small faults converge on the F2 fault, and the fault distribution is clear, and the resolution is high; B is the nearly east-west fault that converges on the F2 fault. The point is clear; the point C is the north-north-east trending fault that meets on the F2 fault, and the fracture point is clear; the point D is a group of 3 north-north-east trending faults arranged in geese, and the distinct...

Embodiment 3

[0138] Example 3 Figures 5(a)-5(f) are the results of the application of the invention in Zhouqingzhuang of Dagang Oilfield. The steps are the same as in Example 1. Figure 5(a) is a section of the 3D seismic data of Zhouqingzhuang Oilfield in Example 3. S31 shown in Figure 5(a) is a layer of bio-limestone reservoir, and S31 to S34 are a set of fluvial sand and mudstone. Interbedded deposition, in which sandstone is also a very good oil and gas reservoir. The second set of oil and gas reservoirs are controlled by small faults. The oil field is in the middle and late stages of development, and it is very important to study the small faults controlled by large faults for controlling oil and gas reservoirs. The study area has developed faults, mainly developed—a group of normal faults that control the rift-shaped depression. It is difficult to interpret the group of normal faults shown in the figure from the seismic profile information. The fracture shown in the picture is the result ...

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Abstract

A seismic coherence algorithm based on wavelet transformation comprises the following steps: 1) preprocessing the seismic data; 2) executing fine frequency spectrum analysis to the processed seismic data for confirming the effective frequency spectrum range of seismic data; 3) executing horizon interpretation to the seismic data and executing processions of interpolation, smoothing, etc.; 4) using seismic data and the interpreted seismic horizon as input, executing wavelet transformation to a certain seismic channel for inputting earthquake data with a high resolution derivative wavelet function for obtaining the wavelet transformation frequency division result; 5) computing the instantaneous amplitude or / and instantaneous frequency or / and instantaneous phase of instantaneous wavelet field; 6) computing the instantaneous coherence using a coherence algorithm based on wavelet instantaneous phase or a coherence algorithm based on wavelet transformation; 7) reconstructing the instantaneous coherence for obtaining high-frequency or low-frequency coherent data volume; 8) repeating the steps 4-7 to each seismic channel for obtaining the coherence computing result of all seismic channels; and 9) drafting with the computed instantaneous coherent data.

Description

Technical field [0001] The invention relates to the technical field of oil and gas field exploration, belongs to the category of seismic data interpretation, and specifically is a method for calculating seismic coherence volume based on wavelet transform. Background technique [0002] Seismic coherence refers to the measurement of similarity of seismic attributes between adjacent seismic traces, such as waveform, amplitude, frequency, phase, etc. [0003] In general, the current coherence is based on the calculation of the amplitude. The three-dimensional amplitude data volume is calculated and converted into the correlation coefficient data volume by using the multi-channel similarity, and the display emphasizes the uncorrelated abnormality and highlights the discontinuity. Its premise is: assuming that the stratum is continuous, the seismic waves are changing and gradual, so the adjacent traces and lines are similar. When the continuity of the formation is destroyed and changes...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01V1/32G01V1/40
Inventor 王西文杨午阳刘军迎
Owner 中国石油集团西北地质研究所有限公司
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