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Method for eliminating single frequency interference in signal of seismological record

A technology of seismic recording and single-frequency interference, which is applied in the field of seismic data processing in the field of petroleum exploration, and can solve problems such as boundary effects, damage to effective wave frequency components, and easy identification of interference waves

Active Publication Date: 2007-11-14
BC P INC CHINA NAT PETROLEUM CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Although the frequency domain processing is simple and convenient, there are the following problems: In the shallow layer, when the energy levels of the effective wave and the interference wave are very close, or the energy of the effective wave is stronger than that of the interference wave, the interference wave is difficult to identify; The energy is weaker than that of the interference wave, and the interference wave is easy to identify at this time
For the interference wave, only the amplitude is suppressed, and the amount of suppression is not easy to grasp. If the suppression is insufficient, there will be residual single-frequency interference waves on the record.
Frequency domain suppression also often damages the effective wave frequency components near the frequency; in order to reduce the damage to the effective wave frequency, it is necessary to select a very narrow suppression frequency band, so that the corresponding time domain operator is very long, which will produce serious boundary effects
At the same time, because the frequency of the strong single-frequency interference wave is affected by the cycle instability, it is often not pure 50Hz, and it is also affected by the selection of the calculation time window, which makes the fast Fourier transform have some insurmountable problems.
[0003] These problems make it difficult to effectively suppress strong single-frequency interference waves in the frequency domain

Method used

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  • Method for eliminating single frequency interference in signal of seismological record
  • Method for eliminating single frequency interference in signal of seismological record
  • Method for eliminating single frequency interference in signal of seismological record

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Effect test

Embodiment 1

[0045] First, a trial calculation is performed using theoretically synthesized data. Theoretical synthetic data uses the sum of an actual seismic trace and a cosine wave. cosine wave using the formula

[0046] the y i =Acos2πf(i+τ)Δt

[0047] Table 1 is the used parameters and estimated parameters, Δt=1 ms. Its curve is shown in Figure 1 (1), and its amplitude value is 10 times of the maximum value of the actual seismic record; Figure 1 (2) is the actual seismic record; Figure 1 (3) is the synthetic seismic record; Figure 1 (4) is the record after suppressing the cosine wave; Figure 1(5) is the result obtained by subtracting Figure 1(4) from Figure 1(3). Fig. 2 is the frequency spectrum corresponding to the curve in Fig. 1, and Fig. 2(a) to Fig. 2(d) are respectively the spectra in Fig. 1(1) to Fig. 1(4). The frequency and delay are exactly the same as the theoretical values, and the amplitude is very consistent with the amplitude of the actual cosine curve, which is also...

Embodiment 2

[0050] Figure 3 is the comparison before and after denoising of the three common receiver gathers of Jilin DH97-551 measuring line 238-240. (a) is the common receiver point gather before denoising, the seismic record length is 5000ms, and the sampling interval is 1ms. Due to display reasons, only 0-3000ms is displayed. They contain strong interference waves around 50Hz, 150Hz and 250Hz; using the method of the present invention, the processing steps are as follows for the first seismic track of the entire seismic record.

[0051] (1) Use the cosine function to represent the single-frequency interference wave:

[0052] the y i =Acos2πf(i+τ)Δt

[0053] Assuming that the amplitude A=1, for a given frequency f=49 and a given delay sample number τ=-10, calculate the single-frequency interference wave y i ; (2) according to the formula (V)

[0054] R ( k ) = Σ ...

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Abstract

The invention is a field seismic data collection technique for petroleum exploration, i.e. on the condition that there is high voltage power line across seismic lines, adopting a method for eliminating monofrequent interference from seismic recording signal to collect original waveform in seismic data Si; on time section, using deep-level time segment to determine amplitude, frequency and time delay of monofrequent strong interference wave yi as monofrequent strong interference wave yi in the whole-channel seismic record, subtracting yi from Si and getting a seismic record without yi, using deep-level seismic data to estimate the monofrequent interference wave, and most effectively estimating energy of the monofrequent interference wave, thus able to furthest eliminate the frequency component of the monofrequent interference wave, avoiding the damage to an effective wave corresponding to the frequency component, and it can eliminate plural monofrequent interference waves one time.

Description

technical field [0001] The invention relates to a processing technology for seismic data collected in the field of oil exploration, in particular to a method for eliminating single-frequency interference in seismic recording signals when a high-voltage transmission line passes above the seismic survey line. Background technique [0002] When single-frequency strong interference waves exist in seismic records, the conventional suppression method is to suppress them in the frequency domain. Although the frequency domain processing is simple and convenient, there are the following problems: In the shallow layer, when the energy levels of the effective wave and the interference wave are very close, or the energy of the effective wave is stronger than that of the interference wave, the interference wave is difficult to identify; The energy is weaker than that of the interference wave, and the interference wave is easy to identify at this time. In deep layers, interfering waves a...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01V1/28G01V1/36
Inventor 高少武周兴元赵波
Owner BC P INC CHINA NAT PETROLEUM CORP
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