Noise suppression evaluation method for three-dimensional observation system

Abstract

The invention relates to a petroleum geophysical prospecting technology, in particular to a noise suppression evaluation method for a three-dimensional observation system in seismic data acquisition. The method comprises the following steps: various three-dimensional seismic exploration and observation system proposals are designed, the CMP attribute information is calculated, the residual moveout between the significant wave and the noise is calculated, and the amplitude stacking characteristic of the noise is calculated according to the residual moveout; the comprehensive amplitude suppression characteristic and the fractional-frequency amplitude suppression characteristic of the noise of each common midpoint are calculated to obtain the statistical characteristic of a frequency chart; and the seismic data is acquired by using the three-dimensional observation system with the minimum value of the amplitude suppression characteristic to obtain a seismic section with high signal-to-noise ratio. The invention achieves the purposes of effectively suppressing the noise, improving the signal-to-noise ratio, improving the data acquisition quality of the three-dimensional observation system and obtaining the seismic section with higher signal-to-noise ratio, thereby enhancing the accuracy of drilling.

Description

technical field [0001] The invention relates to petroleum geophysical exploration technology, in particular to a method for quantitatively estimating the characteristic of suppressing noise of a three-dimensional seismic data acquisition and observation system before seismic data acquisition and construction. technical background [0002] Petroleum seismic exploration technology is to use artificial methods to cause crustal vibrations, and then use precision instruments to record the vibrations of various points on the ground after the explosion, and use the recorded data to infer the crustal structure and formation rocks related to underground oil, natural gas and coal fields. A general term for sexual methods. Due to the different mechanical properties of underground media, seismic waves will cause spatial changes in the frequency, amplitude, phase, velocity, and wave field type of seismic waves during propagation, which can be obtained by using high-precision recording eq...

AI Technical Summary

Problems solved by technology

For a long time, the design and research of these observation systems have focused on migration imaging and resolution, and the research on noise suppression is only limited to the research on surface wave linear noise suppression in the two-dimensional observation mode

The current method for evaluating the suppressed noise characteristics of the 3D observation system is to draw the offset and azimuth distribution diagrams of the CMP gathers (see Figure 4 to Figure 6). The changes of the three in the figure are different, and people distribute The uniformity of velocity analysis is used to judge the accuracy of velocity analysis and the effect of suppressing noise. This method and the understanding obtained are generally qualitative. Since there is no quantitative evaluation index, it is difficult to determine how effective the above-mentioned observation system is for suppressing noise. Therefore, it is inevitable to cause decision-making deviation or mistakes in the selection of 3D observation systems. This is a problem in the design of observation system types at present.

In addition, even for the same type of observation system, with the difference of various specific parameters, such as the change of receiving line distance, receiving point density, shot line distance, shot density and other parameters, the characteristics of suppressing noise are also quite different. These specific parameters cause changes in the noise suppression ability, and there is also a lack of quantitative evaluation methods

In particular, there are more and more types of observation systems used in the field, such as wide azimuth and narrow azimuth, multi-line number and low-line number, high coverage of small bins and low coverage of large bins, etc., resulting in the selection of observation system types and specific parameters. Some fuzzy understandings, unable to determine relatively good specific parameters, this is another problem in the current design of the observation system

Under the three-dimensional observation method, there is no report on the method of suppressing the scattering noise of the observation system

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