Interval velocity inversion method for earthquake waves
A layer velocity and seismic wave technology, applied in the field of seismic exploration data processing, can solve problems such as insufficient first-arrival picking accuracy, inability to improve original data resolution, restricting the application value of VSP data, etc., and achieve the effect of high accuracy
Active Publication Date: 2015-05-13
BC P INC CHINA NAT PETROLEUM CORP +1
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Problems solved by technology
Since the interpolation itself is just a mathematical algorithm, the interpolated signal is not a real signal, which cannot improve the resolution of the original data. At the same time, the interpolation result is greatly affected by the interpolation method and the signal-to-noise ratio, which leads to the first arrival The picking accuracy is not enough, which restricts the application value of VSP data
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[0028] The invention is a method for layer velocity inversion by using the phase spectrum attribute of seismic data.
[0029] Concrete steps of the present invention include:
[0030] 1) The ground source is excited, and the downhole geophone receives the VSP data;
[0031] 2) Pick up the first arrival of each trace of seismic data, round the first arrival time, and then use the rounded first arrival time to calculate the first arrival difference of adjacent traces;
[0032] 3) Use the first arrival after rounding to perform median filter wave field separation on the VSP data to obtain the downgoing wave, and flatten the obtained downgoing wave;
[0033] 4) In the flattened downgoing wave, starting from the first sample point, a time window is opened backward, and the signal in the time window is Fourier transformed to obtain the phase spectrum of each frequency;
[0034] 5) Repeat step 4) to obtain the phase spectrum of each frequency of all downgoing waves;
[0035] 6) Fi...
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The invention relates to an interval velocity inversion method for earthquake waves for processing earthquake exploration data, comprising the steps of receiving the data underground and obtaining VSP (Vertical Seismic Profiling) data, picking each first arrival and integer time, calculating the first arrival difference of adjacent integer sampling points, carrying out median filter wave field separation of the VSP data and obtaining down-going waves and leveling the down-going waves; opening one time window from the first sampling point; carrying out Fourier transform on a signal to obtain the phase spectrum of each frequency; getting the phase spectrum difference of the same frequency in adjacent channels; obtaining the first arrival second difference of non-integer sampling points of the adjacent channels by least square fit; summing the first arrival first difference and the first arrival second difference to obtain the first arrival difference; and obtaining the interval velocity by dividing the depth difference of the adjacent channels by the final first arrival difference of the adjacent channels. The method has strong ability resisting to immediate (random) interference; the algorithm is simple; and the inversion interval velocity has high precision.
Description
technical field [0001] The invention relates to a seismic exploration data processing technology, a method for inversion of seismic layer velocity by using the phase spectrum attribute of seismic data. Background technique [0002] In seismic exploration, because the shot point is very close to the wellhead, the vertical seismic profiling method (VSP) can be considered that the downgoing direct waves received at different depths have the same propagation path, and the interlayer time difference can be calculated directly by using the first arrival time, so as to reflect the It can provide a powerful method for surface seismic processing and interpretation. In the current VSP data processing, when the first arrival is picked, the seismic signal is firstly re-sampled in the time domain to increase the sampling rate. The specific method is to use the values of several adjacent sample points to interpolate more sample point values, for example, interpolate a signal with a sam...
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IPC IPC(8): G01V1/28
Inventor 李彦鹏张固澜
Owner BC P INC CHINA NAT PETROLEUM CORP