CN104133237A - Azimuth seismic wavelet converging method - Google Patents

Abstract

The invention provides an azimuth seismic wavelet converging method, and belongs to the field of seismic prospecting and development of oil gas and coalbed gas. The method comprises the following steps: (1), pretreatment is carried out on azimuth wavelets, and at least two different azimuth wavelets are extracted from the same seismic data or CMP pre-stack data; (2) the main frequency and the main frequency phase of each azimuth wavelet are extracted; and (3) the main frequency and the main frequency phase of each azimuth wavelet obtained in the second step are used for generating a new wavelet. By using the method of the invention, one seismic wavelet can contain characteristics of multiple seismic wavelets.

Description

The fusion method of a kind of orientation seismic wavelet

Technical field

The invention belongs to oil gas and coalbed gas seismic exploration and development field, be specifically related to the fusion method of a kind of orientation seismic wavelet.

Background technology

Seismic wavelet (hereinafter to be referred as wavelet) is the one-component of seismic convolution model, is often referred to the seismic pulse being made up of 2 to 3 or multiple phase place.A wavelet can be defined by its spectral amplitude and phase spectrum, and the type of phase spectrum can be zero phase, constant phase, minimum phase, mixed-phase etc.; For zero phase and constant phase wavelet, can simply be seen as the sinusoidal wave set of a series of various amplitudes and frequency, all sine waves are all (as 90 °) of zero phase or constant phase; In frequency field, wavelet extraction problem is made up of two parts: determine spectral amplitude and phase spectrum, determine that phase spectrum is more difficult, and be the main source of error in inverting.

The extracting method of seismic wavelet mainly contains two large classes: the first kind is determinate wavelet pickup method, and Equations of The Second Kind is statistical wavelet extraction method.Determinate wavelet pickup method refers to utilizes well-log information first to calculate reflection coefficient sequence, then obtains seismic wavelet in conjunction with well lie by convolution theory.Its advantage is not need the distribution of reflection coefficient to do any hypothesis, can obtain wavelet comparatively accurately.And the advantage of statistical method is not need well logging information also can obtain the estimation of wavelet, but shortcoming is to carry out certain hypothesis to the distribution of seismic data used and underground reflection coefficient sequence, and gained wavelet precision is not high.

Three-dimensional prestack CMP geological data refers to through certain processing but passes through the three-dimensional seismic acquisition data (being called for short CMP road collection data) that superpose.CMP road collection data can extract according to different seismic location angles the geological data of some people having a common goal's collection, are called CMP road, orientation collection data.Each CMP road, orientation collection data also can extract corresponding seismic wavelet, is called orientation seismic wavelet.

But, the correlation technique that seismic wavelet does not merge or orientation seismic wavelet merges at present.

Summary of the invention

The object of the invention is to solve the difficult problem existing in above-mentioned prior art, the fusion method of a kind of orientation seismic wavelet is provided, each wavelet that different orientation CMP road collection data are extracted, utilizes permeated wavelet of certain technological means.This wavelet can comprise the key message (frequency, phase place) of each side's seat ripple.Utilizing the wavelet of this type to carry out earthquake prestack inversion or the inverting of earthquake poststack will contribute to react further reservoir characteristic, is exploration, the exploitation service of conventional gas and oil and coal-seam gas.

The present invention is achieved by the following technical solutions:

A fusion method for orientation seismic wavelet, comprises the following steps:

(1) orientation wavelet pre-service: extract at least two different orientation wavelets from same geological data or CMP pre stack data;

(2) dominant frequency and the dominant frequency phase place of extraction each side seat ripple;

(3) utilize dominant frequency and the dominant frequency phase place of each side's seat ripple that step (2) obtains to generate new wavelet.

Described step (2) is specific as follows:

The dominant frequency of each orientation wavelet obtains like this: orientation wavelet is transformed into after frequency field, and frequency corresponding to its frequency spectrum maximum of points is dominant frequency;

Described dominant frequency phase place be describe signal waveform change tolerance, using spend or angle as unit.

Described step (3) is specific as follows:

First, utilize formula (1) and formula (2) that the dominant frequency of all orientation wavelet and dominant frequency phase place are done on average:

$\mathrm{average}\_\mathrm{freq}=\frac{1}{n}\underset{k=1}{\overset{n}{\mathrm{\Σ}}}{\mathrm{freq}}_k$ Formula (1)

$\mathrm{average}\_\mathrm{ph}=\frac{1}{n}\underset{k=1}{\overset{n}{\mathrm{\Σ}}}{\mathrm{ph}}_k$ Formula (2)

In formula (1), average_freq is the average dominant frequency finally obtaining, and freq is the dominant frequency of each orientation wavelet, and n represents total n orientation wavelet, and k represents the sequence number of orientation wavelet;

In formula (2), average_ph is the average dominant frequency phase place finally obtaining, and ph is the dominant frequency phase place of each orientation wavelet;

Then, utilize formula (3) to generate new wavelet:

b(t)＝e ^-at2Sin2πft

Formula (3)

In formula (3), t is the sampling time, and b is the number of samples of new wavelet, and a is wavelet attenuation coefficient, and f is dominant frequency, and the averagefreq that will be obtained by formula (1), as f substitution formula (3), tries to achieve wavelet b (t);

Recycling formula (4) is asked its frequency spectrum by wavelet b (t) by Fourier transform:

formula (4)

In formula (4), | B (ω) | be wavelet amplitude, be the phase spectrum of wavelet, specifically obtain like this:

| B (ω) | be wavelet amplitude, its formula is and ask mould to obtain B (ω) | B (ω) |;

the phase spectrum of wavelet, wherein imag (B (w)) is the imaginary part of frequency spectrum, and real (B (w)) is the real part of frequency spectrum;

Finally, using average_ph as substitution formula (4), recycles afterwards inverse Fourier transform B (ω) is generated to new wavelet b1 (t), the new wavelet after this wavelet merges.

In described formula (3), the number of samples b of sampling time t, new wavelet and be that wavelet attenuation coefficient a is inputted by user.

Compared with prior art, the invention has the beneficial effects as follows: utilize the inventive method can make a seismic wavelet can comprise the characteristic of multiple seismic wavelets.

Brief description of the drawings

Fig. 1 is the step block diagram of the fusion method of orientation of the present invention seismic wavelet.

Fig. 2 is the seismic wavelet A in the embodiment of the present invention.

Fig. 3 is the seismic wavelet B in the embodiment of the present invention.

Fig. 4 is the seismic wavelet C in the embodiment of the present invention.

Fig. 5 is the new seismic wavelet utilizing in the embodiment of the present invention after the inventive method merges Fig. 2, Fig. 3 and tri-wavelets of Fig. 4.

Embodiment

Below in conjunction with accompanying drawing, the present invention is described in further detail:

The method the present invention relates to is to be applicable to taking lithologic trap as the main exploratory development of conventional gas and oil and the exploratory development of unconventional (coal-seam gas and shale gas) oil gas, the key point of the inventive method comprises each wavelet that different orientation CMP road collection data are extracted, and utilizes permeated wavelet of certain technological means.This wavelet can comprise the key message (frequency, phase place) of each side's seat ripple.Utilizing the wavelet of this type to carry out earthquake prestack inversion or the inverting of earthquake poststack will contribute to further to react reservoir characteristic, is exploration, the exploitation service of conventional gas and oil and coal-seam gas.

As shown in Figure 1, the fusion method of orientation of the present invention seismic wavelet comprises following three steps:

(1) orientation wavelet pre-service:

First wavelet merges need to extract multiple different orientation wavelets from same geological data or CMP pre stack data, can not from multiple geological datas, extract, otherwise can not ensure that finally the wavelet of fusion can effectively be applied.

(2) ask for the key parameter of each side's seat ripple:

Dominant frequency and the dominant frequency phase place of extracting each orientation wavelet, wherein the dominant frequency of each orientation wavelet obtains like this: orientation wavelet data are transformed into after frequency field, and frequency corresponding to its frequency spectrum maximum of points is called dominant frequency; Dominant frequency phase place (phase) is to describe the tolerance that signal waveform changes, conventionally using degree (angle) as unit, also referred to as phase angle.When signal waveform changes in the mode in cycle, waveform cycle is 360 ° for one week.

(3) orientation wavelet merges

The dominant frequency of multiple orientation wavelet and dominant frequency phase place are done on average,

$\mathrm{average}\_\mathrm{freq}=\frac{1}{n}\underset{k=1}{\overset{n}{\mathrm{\Σ}}}{\mathrm{freq}}_k$ Formula (1)

$\mathrm{average}\_\mathrm{ph}=\frac{1}{n}\underset{k=1}{\overset{n}{\mathrm{\Σ}}}{\mathrm{ph}}_k$ Formula (2)

In formula (1), average_freq is the average dominant frequency finally obtaining, the dominant frequency that freq is each wavelet, and n represents total n wavelet, k represents wavelet sequence number; In formula (2), average_ph is the average dominant frequency phase place finally obtaining, the dominant frequency phase place that ph is each wavelet, and n represents total n wavelet, k represents wavelet sequence number.

Utilize formula (1) and the result of calculation of formula (2) to generate new wavelet, its flow process is as follows

B (t)=e ^-at2sin2 π ft formula (3)

In formula (3), t is sampling time (this time is inputted by user), and b is that (number of samples of each wavelet need not be identical, on calculating not impact for the number of samples of wavelet; The number of samples of new wavelet is inputted by user), a is wavelet attenuation coefficient (being inputted by user), f is dominant frequency, and average_freq, as f (dominant frequency) substitution formula 3, is tried to achieve to wavelet b (t).

Ask its frequency spectrum to be by Fourier transform wavelet b (t) again:

formula (4)

In formula (4), | B (ω) | be wavelet amplitude, be the phase spectrum of wavelet, specifically obtain like this:

| B (ω) | be wavelet amplitude, its formula is and ask mould to obtain B (ω) | B (ω) |.

the phase spectrum of wavelet, wherein imag (B (w)) is the imaginary part of frequency spectrum, and real (B (w)) is the real part of frequency spectrum.

By average_ph as (phase place) substitution formula (4), recycle afterwards inverse Fourier transform (formula is: ) B (ω) is generated to new wavelet data b1 (t).Wavelet after this wavelet namely merges.

In Fig. 1, the part in dotted line frame is to adopt prior art, in scope of the present invention.

Utilize one embodiment of the present of invention specifically as shown in Figures 2 to 5, wherein Fig. 2 is seismic wavelet A, its name is called RicherWavelet-018, number of samples is 65, dominant frequency is 35.156, dominant frequency phase place is 90.000, Fig. 3 is seismic wavelet B, its name is called RicherWavelet-017, number of samples is 65, dominant frequency is 23.437, dominant frequency phase place is 180.000, Fig. 4 is seismic wavelet C, its name is called RicherWavelet-013, number of samples is 65, dominant frequency is 31.250, dominant frequency phase place is 0.000, Fig. 5 is the new seismic wavelet forming after the seismic wavelet in Fig. 2 to Fig. 4 is merged, its name is called mergeWavelet_001, number of samples is 128.The number of samples of new wavelet can arrange arbitrarily according to the actual requirements, there is no what special relation with former wavelet sampling point number, can be different from former wavelet number of samples, but be preferably between 32～1024.In Fig. 2 to Fig. 5, upper part is wavelet form, and lower part is wavelet spectrum.

Technique scheme is one embodiment of the present invention, for those skilled in the art, the invention discloses on the basis of application process and principle, be easy to make various types of improvement or distortion, and be not limited only to the described method of the above-mentioned embodiment of the present invention, therefore previously described mode is just preferred, and does not have restrictive meaning.

Claims (4)

1. a fusion method for orientation seismic wavelet, is characterized in that: said method comprising the steps of:

(1) orientation wavelet pre-service: extract at least two different orientation wavelets from same geological data or CMP pre stack data;

(2) dominant frequency and the dominant frequency phase place of extraction each side seat ripple;

(3) utilize dominant frequency and the dominant frequency phase place of each side's seat ripple that step (2) obtains to generate new wavelet.

2. the fusion method of orientation according to claim 1 seismic wavelet, is characterized in that: described step (2) is specific as follows:

The dominant frequency of each orientation wavelet obtains like this: orientation wavelet is transformed into after frequency field, and frequency corresponding to its frequency spectrum maximum of points is dominant frequency;

Described dominant frequency phase place be describe signal waveform change tolerance, using spend or angle as unit.

3. the fusion method of orientation according to claim 2 seismic wavelet, is characterized in that: described step (3) is specific as follows:

First, utilize formula (1) and formula (2) that the dominant frequency of all orientation wavelet and dominant frequency phase place are done on average:

$\mathrm{average}\_\mathrm{freq}=\frac{1}{n}\underset{k=1}{\overset{n}{\mathrm{\Σ}}}{\mathrm{freq}}_k$ Formula (1)

$\mathrm{average}\_\mathrm{ph}=\frac{1}{n}\underset{k=1}{\overset{n}{\mathrm{\Σ}}}{\mathrm{ph}}_k$ Formula (2)

In formula (1), average_freq is the average dominant frequency finally obtaining, and freq is the dominant frequency of each orientation wavelet, and n represents total n orientation wavelet, and k represents the sequence number of orientation wavelet;

In formula (2), average_ph is the average dominant frequency phase place finally obtaining, and ph is the dominant frequency phase place of each orientation wavelet;

Then, utilize formula (3) to generate new wavelet:

b(t)＝e ^-at2Sin2πft

Formula (3)

In formula (3), t is the sampling time, and b is the number of samples of new wavelet, and a is wavelet attenuation coefficient, and f is dominant frequency, and the averagefreq that will be obtained by formula (1), as f substitution formula (3), tries to achieve wavelet b (t);

Recycling formula (4) is asked its frequency spectrum by wavelet b (t) by Fourier transform:

formula (4)

In formula (4), | B (ω) | be wavelet amplitude, be the phase spectrum of wavelet, specifically obtain like this:

| B (ω) | be wavelet amplitude, its formula is and ask mould to obtain B (ω) | B (ω) |;

the phase spectrum of wavelet, wherein imag (B (w)) is the imaginary part of frequency spectrum, and real (B (w)) is the real part of frequency spectrum;

Finally, using average_ph as substitution formula (4), recycles afterwards inverse Fourier transform B (ω) is generated to new wavelet b1 (t), the new wavelet after this wavelet merges.

4. the fusion method of orientation according to claim 1 seismic wavelet, is characterized in that: in described formula (3), and the number of samples b of sampling time t, new wavelet and be that wavelet attenuation coefficient a is inputted by user.