Frequency division matched filtering method for improving offshore seismic data resolution by utilizing seismic focuses of different depths

A technology of seismic data and matched filter, applied in the direction of seismic signal processing, etc., can solve the problems of difficulty in obtaining seismic records, restricting high-resolution exploration of offshore oil and gas, restricting resolution, etc.

Inactive Publication Date: 2012-10-24
ZHEJIANG UNIV
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Problems solved by technology

However, the existence of ghost reflections in offshore exploration seriously restricts the improvement of resolution. The source wavelets excited at different depths will have differences in frequency bands due to the difference in ghost reflection notch points. The shallow source ha...

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  • Frequency division matched filtering method for improving offshore seismic data resolution by utilizing seismic focuses of different depths
  • Frequency division matched filtering method for improving offshore seismic data resolution by utilizing seismic focuses of different depths
  • Frequency division matched filtering method for improving offshore seismic data resolution by utilizing seismic focuses of different depths

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Embodiment Construction

[0055] The method for improving the resolution of marine seismic data by using airgun sources at different depths, the steps are as follows:

[0056] 1) Excite the airgun source at different depths to obtain near-field wavelets:

[0057] Place the airgun seismic source at different depths at the same sea level point to excite, and use the hydrophone to record the near-field wavelet of the seismic source at a distance of 1 meter vertically above the seismic source. The specific observation method is as follows: figure 1 as shown, figure 2 The simulated near-field wavelets are excited by the airgun at depths of 6 meters and 10 meters respectively. It can be seen that the oscillation period and initial bubble ratio of the near-field wavelets excited at different depths are different; if necessary, the airgun source can also Can be placed at depths of 3 or 15 meters at the same sea level site.

[0058] 2) The far-field wavelet is obtained by simulation:

[0059] Let the depth h ...

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Abstract

The invention discloses a method for improving offshore seismic data resolution by utilizing air gun seismic focuses of different depths. The method is characterized in that air guns are respectively arranged in positions of different depths to be excited, the near-field wavelet of each seismic focus is recorded, and a far-field wavelet is obtained through simulation; and because of the existence of an offshore strong wave impedance interface, trap points occur on the frequency spectrum of each far-field wavelet, the high-frequency information of air gun seismic focuses at superficial parts is rich, the low-frequency advantages of seismic focuses at deep parts are obvious, and periodic extension is formed. The spectral analysis is carried out on the far-field wavelets to determine the dominant frequency band of each wavelet, the high-frequency dominant section of the wavelet at a superficial part is kept unchanged, the far-field wavelet of the seismic focus at a deep part is expected to be output only at the low-frequency end, and a frequency division matched filter is obtained by calculation and then is applied to all seismic records acquired by the air gun seismic focuses at the superficial parts, thereby realizing the combination of advantages of wavelets of seismic focuses in two different depths, widening the frequency band of the offshore seismic data and improving the resolution.

Description

technical field [0001] The invention relates to the field of marine seismic exploration, in particular to a method for improving the resolution of marine seismic data by using airgun sources of different depths. Background technique [0002] The 21st century is the century of the ocean. Offshore oil and gas resources are extremely rich. After long-term exploration on land and shallow seas around the world, the number of major oil and gas discoveries has become less and less. Oil companies have turned their attention to the deep sea where the degree of exploration is still very low. However, the existence of ghost reflections in offshore exploration seriously restricts the improvement of resolution. The source wavelets excited at different depths will have differences in frequency bands due to the difference in ghost reflection notch points. The shallow source has rich high-frequency components, but the low-frequency end is not as good as the deep one. Therefore, it is diffic...

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Application Information

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IPC IPC(8): G01V1/36
Inventor 田钢沈洪垒石战结
Owner ZHEJIANG UNIV
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