CN101581791A - Method for extracting pre-stack hydrocarbon detection section of seismic data with low signal-to-noise ratio - Google Patents

Abstract

The invention relates to geophysical exploration seismic data processing technology, and discloses a method for extracting a pre-stack hydrocarbon detection section of seismic data with low signal-to-noise ratio. The method comprises the processing steps of: performing separation of common mid-point gathers on the seismic data through processing of pre-stack preserved amplitude of the seismic data to evaluate the seismic data velocity, and performing dynamic correction on the processed data to obtain the seismic data after the dynamic correction; utilizing a Zoeppritz equation to process the seismic data after the dynamic correction; and mixing the data obtained by the processing for two times according to the percentage to form new seismic data to obtain a pre-stack attribute section and a hydrocarbon detection section. The method is applicable to the pre-stack attribute extraction of the seismic data with low signal-to-noise ratio, does not limit the range of an incidence angle of the seismic data which participate in the attribute extraction, and can improve the signal-to-noise ratio of the pre-stack seismic data by fitting a seismic reflection coefficient which changes with the incidence angle, thereby obtaining an accurate zero offset reflection coefficient.

Description

A kind of pre-stack hydrocarbon detection section of seismic data with low signal-to-noise ratio extracting method

Technical field

This method relates to geophysical survey geological data prestack attributive analysis and petroleum-gas prediction technology, specifically is a kind of pre-stack hydrocarbon detection section of seismic data with low signal-to-noise ratio extracting method.

Background technology

It is to predict lithology in the seismic prospecting that geological data prestack amplitude changes with offset distance, the important technology of reservoir, on elastic oscillation theory of mechanics basis, utilize theory of mathematical physics can describe the rule that reflection amplitude changes with incident angle (or geophone offset), because this variation is that subsurface rock and property of pore fluid thereof cause, also just established according to amplitude information prediction lithology, and the mathematical physics basis of property of pore fluid.But because the utilization of prestack attributes extraction is the geological data of prestack, the geological data before the stack is subjected to noise effect, and generally signal to noise ratio (S/N ratio) is lower, and it is unreliable that the pre-stack hydrocarbon detection section of seismic data with low signal-to-noise ratio extracts precision.

In addition, present method can not improve the signal to noise ratio (S/N ratio) of earthquake data before superposition by the seismic reflection coefficient that match changes with incident angle, and also the geological data ranges of incidence angles of attributes extraction is participated in restriction, thereby can not obtain accurate zero shot-geophone distance reflection coefficient.It is low that the earthquake data before superposition hydrocarbon detection section extracts precision, can not make reasonable petroleum-gas prediction in conjunction with drilling data and local conditions.

Summary of the invention

The object of the invention is to provide a kind of noise attenuation to the interference of amplitude with the offset distance variation, realizes reliable pre-stack hydrocarbon detection section of seismic data with low signal-to-noise ratio extracting method.

Process of the present invention comprises following treatment step:

1) use the conventional means acquiring seismic data, by the preserved amplitude processing of geological data prestack, the geological data after the acquisition pre-stack processing;

2) geological data is carried out common midpoint gather (CMP) sorting;

The described sorting of step (2) is next geological data to same the vertical line on the face of land to be put together form a common midpoint gather.

3) carry out seismic data in handling the conventional speeds analysis and ask for seismic data speed;

4) with in the seismic data speed of trying to achieve to step 2) data after handling carry out the normal moveout correction (TEC time error correction) in the conventional earthquake data processing, obtain the geological data after the normal moveout correction;

5) geological data after utilizing approximate expression that Shuey proposed the Zoeppritz equation to normal moveout correction carries out following processing:

$R\left(\mathrm{\&alpha;}\right){\mathrm{<figure-callout\; id="2"\; label="cos"\; filenames="A2008101117430014H1.png,A2008101117430014H2.png"\; state="\{\{state\}\}">cos</figure-callout>}}^2\mathrm{\&alpha;}\&ap;\frac{1}{2}(\frac{\mathrm{\&Delta;}{v}_P}{v_p}+\frac{\mathrm{\&Delta;\&rho;}}{\mathrm{\&rho;}})-(\frac{1}{2}\frac{\mathrm{\&Delta;\&rho;}}{\mathrm{\&rho;}}+4\frac{v_s^2}{v_{\mathrm{<figure-callout\; id="2"\; label="p"\; filenames="A2008101117430014H1.png,A2008101117430014H2.png"\; state="\{\{state\}\}">p</figure-callout>}}^2}\frac{\mathrm{\&Delta;}{v}_s}{v_s}+2\frac{v_s^2}{v_{\mathrm{<figure-callout\; id="2"\; label="p"\; filenames="A2008101117430014H1.png,A2008101117430014H2.png"\; state="\{\{state\}\}">p</figure-callout>}}^2}\frac{\mathrm{\&Delta;\&rho;}}{\mathrm{\&rho;}}){\mathrm{<figure-callout\; id="2"\; label="sin"\; filenames="A2008101117430014H1.png,A2008101117430014H2.png"\; state="\{\{state\}\}">sin</figure-callout>}}^2\mathrm{\&alpha;}+(4\frac{v_s^2}{v_{\mathrm{<figure-callout\; id="2"\; label="p"\; filenames="A2008101117430014H1.png,A2008101117430014H2.png"\; state="\{\{state\}\}">p</figure-callout>}}^2}\frac{\mathrm{\&Delta;}{v}_s}{v_s}+2\frac{v_s^2}{v_{\mathrm{<figure-callout\; id="2"\; label="p"\; filenames="A2008101117430014H1.png,A2008101117430014H2.png"\; state="\{\{state\}\}">p</figure-callout>}}^2}\frac{\mathrm{\&Delta;\&rho;}}{\mathrm{\&rho;}}){\sin }^4\mathrm{\&alpha;}---\left(1\right)$

Wherein: ρ represents density density, v _sThe expression shear wave velocity, v _pThe expression velocity of longitudinal wave, α represents the seismic event incident angle; When:

Y＝R(α)cos ²α； $A=R_0=(\frac{\mathrm{\&Delta;}{V}_p}{V_p}+\frac{\mathrm{\&Delta;\&rho;}}{\mathrm{\&rho;}})/2;$

$B=-(\frac{1}{2}\frac{\mathrm{\&Delta;\&rho;}}{\mathrm{\&rho;}}+C);$ $C=2\frac{{v_s}^2}{{v_p}^2}(\frac{2\mathrm{\&Delta;}{v}_s}{v_s}+\frac{\mathrm{\&Delta;\&rho;}}{\mathrm{\&rho;}});$

X＝sin ²α

Then:

Y≈A+BX+CX ²(2)

$\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{(A+{\mathrm{BX}}_i+C{X_i}^2-Y_i)}^2=\mathrm{Min}---\left(3\right)$

In the following formula: n is for participating in the number of the incident angle of calculating, and Min is a least error;

More than three formulas respectively to A, B, C carry out differential and obtain three system of equations:

$\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}(A+{\mathrm{BX}}_i+{{\mathrm{CX}}_i}^2)=\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{Y}_i---\left(4\right)$

$\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}(A+{\mathrm{BX}}_i+{{\mathrm{CX}}_i}^2)X_i=\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{Y}_i{X}_i---\left(5\right)$

$\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}(A+{\mathrm{BX}}_i+{{\mathrm{CX}}_i}^2){X_i}^2=\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{Y}_i{X_i}^2---\left(6\right)$

A in the solving equation, B, value and the inverse iteration of C go into (2) formula and obtain Y,

Calculate reflection R (α)-Y/cos ²α (7)

6) data that step 4) is handled are mixed with the data precentagewise that step 5) is handled, and form new geological data;

The described number percent of step 6) determines that according to the geological data signal to noise ratio (S/N ratio) geological data signal to noise ratio (S/N ratio) is low, the number percent height that the data after step 5) is handled account for;

The described number percent of step 6), when earthquake data signal to noise ratio (S/N ratio) was low, it was 30%-80% that the data after step 5) is handled account for percentage ranges, it is 5%-50% that the data after the data that the geological data signal to noise ratio (S/N ratio) is high and step 5) are handled account for percentage ranges.

7) if the hydrocarbon detection section resolution that the geological data signal to noise ratio (S/N ratio) after handling is extracted is low, or obscurity boundary, repeating step 5) and 6), till obtaining the needed signal to noise ratio (S/N ratio) of prestack attributes extraction;

8) obtain B by formula (1), the C value is obtained parameter

Obtain parameter by the A value

By

Ratio obtain parameter By formula $\frac{1}{2}(\frac{\mathrm{\&Delta;}{V}_p}{V_p}+\frac{\mathrm{\&Delta;\&rho;}}{\mathrm{\&rho;}})*\frac{1}{2}(-\frac{\mathrm{\&Delta;\&rho;}}{\mathrm{\&rho;}}+\frac{\mathrm{\&Delta;}{V}_p}{V_p}-2\frac{\mathrm{\&Delta;}{v}_s}{v_s})$ Obtain prestack attribute section and hydrocarbon detection section.

Step 8) is described

The empirical value of ratio be generally

Can get 1.5-2.5 as the case may be.

The present invention is applicable to seismic data with low signal-to-noise ratio prestack attributes extraction, do not limit the geological data ranges of incidence angles of participating in attributes extraction, can improve the signal to noise ratio (S/N ratio) of earthquake data before superposition with the seismic reflection coefficient that incident angle changes by match, thereby obtain accurate zero shot-geophone distance reflection coefficient.Handle back geological data signal to noise ratio (S/N ratio) and improve, guarantee that the earthquake data before superposition hydrocarbon detection section extracts precision, can make reasonable petroleum-gas prediction in conjunction with drilling data and local conditions.

Description of drawings

CMP road collection before the actual earthquake data processing of Fig. 1 (a);

CMP road collection after the actual earthquake data processing of Fig. 1 (b);

Hydrocarbon detection section before the actual earthquake data processing of Fig. 2 (a);

Hydrocarbon detection section after the actual earthquake data processing of Fig. 2 (b);

Embodiment

Seismic data with low signal-to-noise ratio prestack attributes extraction method of the present invention is to improve the method that noise is recently guaranteed prestack attributes extraction precision by pre-stack processing.

The pre-stack hydrocarbon detection section of seismic data with low signal-to-noise ratio leaching process comprises following treatment step:

1) use the conventional means acquiring seismic data, by the preserved amplitude processing of geological data prestack, the geological data after the acquisition pre-stack processing;

2) geological data is carried out common midpoint gather (CMP) sorting;

The described sorting of step (2) is next geological data to same the vertical line on the face of land to be put together form a common midpoint gather.

3) carry out seismic data in handling the conventional speeds analysis and ask for seismic data speed;

4) with in the seismic data speed of trying to achieve to step 2) data after handling carry out the normal moveout correction (TEC time error correction) in the conventional earthquake data processing, obtain the geological data after the normal moveout correction;

5) geological data after utilizing approximate expression that Shuey proposed the Zoeppritz equation to normal moveout correction carries out following processing:

$R\left(\mathrm{\&alpha;}\right){\mathrm{<figure-callout\; id="2"\; label="cos"\; filenames="A2008101117430014H1.png,A2008101117430014H2.png"\; state="\{\{state\}\}">cos</figure-callout>}}^2\mathrm{\&alpha;}\&ap;\frac{1}{2}(\frac{\mathrm{\&Delta;}{v}_P}{v_p}+\frac{\mathrm{\&Delta;\&rho;}}{\mathrm{\&rho;}})-(\frac{1}{2}\frac{\mathrm{\&Delta;\&rho;}}{\mathrm{\&rho;}}+4\frac{v_s^2}{v_{\mathrm{<figure-callout\; id="2"\; label="p"\; filenames="A2008101117430014H1.png,A2008101117430014H2.png"\; state="\{\{state\}\}">p</figure-callout>}}^2}\frac{\mathrm{\&Delta;}{v}_s}{v_s}+2\frac{v_s^2}{v_{\mathrm{<figure-callout\; id="2"\; label="p"\; filenames="A2008101117430014H1.png,A2008101117430014H2.png"\; state="\{\{state\}\}">p</figure-callout>}}^2}\frac{\mathrm{\&Delta;\&rho;}}{\mathrm{\&rho;}}){\mathrm{<figure-callout\; id="2"\; label="sin"\; filenames="A2008101117430014H1.png,A2008101117430014H2.png"\; state="\{\{state\}\}">sin</figure-callout>}}^2\mathrm{\&alpha;}+(4\frac{v_s^2}{v_{\mathrm{<figure-callout\; id="2"\; label="p"\; filenames="A2008101117430014H1.png,A2008101117430014H2.png"\; state="\{\{state\}\}">p</figure-callout>}}^2}\frac{\mathrm{\&Delta;}{v}_s}{v_s}+2\frac{v_s^2}{v_{\mathrm{<figure-callout\; id="2"\; label="p"\; filenames="A2008101117430014H1.png,A2008101117430014H2.png"\; state="\{\{state\}\}">p</figure-callout>}}^2}\frac{\mathrm{\&Delta;\&rho;}}{\mathrm{\&rho;}}){\sin }^4\mathrm{\&alpha;}---\left(1\right)$

Wherein: ρ represents density density, v _sThe expression shear wave velocity, v _pThe expression velocity of longitudinal wave, α represents the seismic event incident angle; When:

Y＝R(α)cos? ²α； $A=R_0=(\frac{\mathrm{\&Delta;}{V}_p}{V_p}+\frac{\mathrm{\&Delta;\&rho;}}{\mathrm{\&rho;}})/2;$

$B=-(\frac{1}{2}\frac{\mathrm{\&Delta;\&rho;}}{\mathrm{\&rho;}}+C);$ $C=2\frac{{v_s}^2}{{v_p}^2}(\frac{2\mathrm{\&Delta;}{v}_s}{v_s}+\frac{\mathrm{\&Delta;\&rho;}}{\mathrm{\&rho;}});$

X＝sin ²α

Then:

Y≈A+BX+CX ²(2)

$\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{(A+{\mathrm{BX}}_i+C{X_i}^2-Y_i)}^2=\mathrm{Min}---\left(3\right)$

In the following formula: n is for participating in the number of the incident angle of calculating, and Min is a least error;

More than three formulas respectively to A, B, C carry out differential and obtain three system of equations:

$\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}(A+{\mathrm{BX}}_i+{{\mathrm{CX}}_i}^2)=\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{Y}_i---\left(4\right)$

$\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}(A+{\mathrm{BX}}_i+{{\mathrm{CX}}_i}^2)X_i=\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{Y}_i{X}_i---\left(5\right)$

$\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}(A+{\mathrm{BX}}_i+{{\mathrm{CX}}_i}^2){X_i}^2=\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{Y}_i{X_i}^2---\left(6\right)$

A in the solving equation, B, value and the inverse iteration of C go into (2) formula and obtain Y,

Calculate reflection R (α)=Y/cos ²α (7)

6) data that step 4) is handled are mixed with the data precentagewise that step 5) is handled, and form new geological data;

The described number percent of step 6) determines that according to the geological data signal to noise ratio (S/N ratio) geological data signal to noise ratio (S/N ratio) is low, the number percent height that the data after step 5) is handled account for;

The described number percent of step 6), when earthquake data signal to noise ratio (S/N ratio) was low, it was 30%-80% that the data after step 5) is handled account for percentage ranges, it is 5%-50% that the data after the data that the geological data signal to noise ratio (S/N ratio) is high and step 5) are handled account for percentage ranges.

7) if the hydrocarbon detection section resolution that the geological data signal to noise ratio (S/N ratio) after handling is extracted is low, or obscurity boundary, repeating step 5) and 6), till obtaining the needed signal to noise ratio (S/N ratio) of prestack attributes extraction;

8) obtain B by formula (1), the C value is obtained parameter

Obtain parameter by the A value

By Ratio obtain parameter By formula $\frac{1}{2}(\frac{\mathrm{\&Delta;}{V}_p}{V_p}+\frac{\mathrm{\&Delta;\&rho;}}{\mathrm{\&rho;}})*\frac{1}{2}(-\frac{\mathrm{\&Delta;\&rho;}}{\mathrm{\&rho;}}+\frac{\mathrm{\&Delta;}{V}_p}{V_p}-2\frac{\mathrm{\&Delta;}{v}_s}{v_s})$ Obtain prestack attribute section and hydrocarbon detection section.

Step 8) is described

The empirical value of ratio be generally

Can get 1.5-2.5 as the case may be.

Fig. 1 (a) is that the physical location of two CMP road collection just in time is the top of KL arch structure, as Fig. 2 (a) with two CMP road composite sections after the pre-stack processing normal moveout correction of the survey line in gas field as test objective.From these two CMP road composite sections, the geological data signal to noise ratio (S/N ratio) is on the low side, observe on the whole, can on the position, reflection horizon at 1670 milliseconds of places, see the faint trend that amplitude changes with geophone offset, but owing to be subjected to noise effect, different geophone offsets are at the geological data amplitude energy of this one deck position and inhomogeneous, and phase differential also appears in some seismic traces, and this will have a strong impact on the extraction precision of earthquake data before superposition attribute.

After this method processing, two CMP road collection geological data signal to noise ratio (S/N ratio)s are improved, can clearly distinguish the trend that amplitude changes with geophone offset at the position, reflection horizon at 1670 milliseconds of places lineups, this obvious positive anomaly phenomenon must occur on hydrocarbon detection attribute section.Comparison diagram 2 (a), (b) can observe significantly, this method is handled the back hydrocarbon detection section has significant change before handling, at first see Fig. 2 (a), can find that the position of KL# well does not have the positive anomaly phenomenon of hydrocarbon detection on the KL arch structure, and on same position Fig. 2 (b), can clearly see hydrocarbon detection positive anomaly phenomenon.Coincideing of this hydrocarbon detection positive anomaly phenomenon and producing oil well position proved that fully this seismic data with low signal-to-noise ratio attributes extraction method is effective feasible.

Claims (6)

1, a kind of pre-stack hydrocarbon detection section of seismic data with low signal-to-noise ratio extracting method is characterized in that comprising following treatment step:

1) use the conventional means acquiring seismic data, by the preserved amplitude processing of geological data prestack, the geological data after the acquisition pre-stack processing;

2) geological data is carried out common midpoint gather (CMP) sorting;

3) carry out seismic data in handling the conventional speeds analysis and ask for seismic data speed;

4) with in the seismic data speed of trying to achieve to step 2) data after handling carry out the normal moveout correction (TEC time error correction) in the conventional earthquake data processing, obtain the geological data after the normal moveout correction;

5) geological data of the approximate expression that utilizes the Zoeppritz equation after to normal moveout correction handled;

6) data that step 4) is handled are mixed with the data precentagewise that step 5) is handled, and form new geological data;

7) if the hydrocarbon detection section resolution that the geological data signal to noise ratio (S/N ratio) after handling is extracted is low, or obscurity boundary, repeating step 5) and 6), till obtaining the needed signal to noise ratio (S/N ratio) of prestack attributes extraction;

8) obtain B, after the C value, obtain parameter Obtain parameter by the A value

By

Ratio obtain parameter By formula $\frac{1}{2}(\frac{{\mathrm{\&Delta;V}}_p}{V_p}+\frac{\mathrm{\&Delta;\&rho;}}{\mathrm{\&rho;}})*\frac{1}{2}(-\frac{\mathrm{\&Delta;\&rho;}}{\mathrm{\&rho;}}+\frac{{\mathrm{\&Delta;V}}_p}{V_p}-2\frac{{\mathrm{\&Delta;v}}_s}{v_s})$ Obtain prestack attribute section and hydrocarbon detection section.

2, pre-stack hydrocarbon detection section of seismic data with low signal-to-noise ratio extracting method according to claim 1 is characterized in that the described sorting of step (2) is next geological data to same the vertical line on the face of land to be put together form a common midpoint gather.

3, pre-stack hydrocarbon detection section of seismic data with low signal-to-noise ratio extracting method according to claim 1 is characterized in that the computing of step 6) is:

$R\left(\mathrm{\&alpha;}\right){\cos }^2\mathrm{\&alpha;}\&ap;\frac{1}{2}(\frac{{\mathrm{\&Delta;v}}_P}{v_p}+\frac{\mathrm{\&Delta;\&rho;}}{\mathrm{\&rho;}})-(\frac{1}{2}\frac{\mathrm{\&Delta;\&rho;}}{\mathrm{\&rho;}}+4\frac{{v_s}^2}{{v_p}^2}\frac{{\mathrm{\&Delta;v}}_s}{v_s}+2\frac{{v_s}^2}{{v_p}^2}\frac{\mathrm{\&Delta;\&rho;}}{\mathrm{\&rho;}}){\sin }^2\mathrm{\&alpha;}+(4\frac{{v_s}^2}{{v_p}^2}\frac{{\mathrm{\&Delta;v}}_s}{v_s}+2\frac{{v_s}^2}{{v_p}^2}\frac{\mathrm{\&Delta;\&rho;}}{\mathrm{\&rho;}}){\sin }^4\mathrm{\&alpha;}---\left(1\right)$

Wherein: ρ represents density density, v _sThe expression shear wave velocity, v _pThe expression velocity of longitudinal wave, α represents the seismic event incident angle; When:

Y＝R(α)cos ²α； $A=R_0=(\frac{{\mathrm{\&Delta;V}}_p}{V_p}+\frac{\mathrm{\&Delta;\&rho;}}{\mathrm{\&rho;}})/2;$

$B=-(\frac{1}{2}\frac{\mathrm{\&Delta;\&rho;}}{\mathrm{\&rho;}}+C);$ $C=2\frac{{v_s}^2}{{v_p}^2}(\frac{2{\mathrm{\&Delta;v}}_s}{v_s}+\frac{\mathrm{\&Delta;\&rho;}}{\mathrm{\&rho;}});$

X＝sin ²α

Then:

Y≈A+BX+CX ² (2)

$\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{(A+{\mathrm{BX}}_i+{{\mathrm{CX}}_i}^2-Y_i)}^2=\mathrm{Min}---\left(3\right)$

In the following formula: n is for participating in the number of the incident angle of calculating, and Min is a least error;

More than three formulas respectively to A, B, C carry out differential and obtain three system of equations:

$\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}(A+{\mathrm{BX}}_i+{{\mathrm{CX}}_i}^2)=\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{Y}_i---\left(4\right)$

$\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}(A+{\mathrm{BX}}_i+{{\mathrm{CX}}_i}^2)X_i=\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{Y}_i{X}_i---\left(5\right)$

$\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}(A+{\mathrm{BX}}_i+{{\mathrm{CX}}_i}^2){X_i}^2=\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{Y}_i{X_i}^2---\left(6\right)$

A in the solving equation, B, value and the inverse iteration of C go into (2) formula and obtain Y,

Calculate reflection R (α)=Y/cos ²α (7).

4, pre-stack hydrocarbon detection section of seismic data with low signal-to-noise ratio extracting method according to claim 1, it is characterized in that the described number percent of step 6) is definite according to the geological data signal to noise ratio (S/N ratio), the geological data signal to noise ratio (S/N ratio) is low, the number percent height that the data after step 5) is handled account for.

5, pre-stack hydrocarbon detection section of seismic data with low signal-to-noise ratio extracting method according to claim 1, it is characterized in that the described number percent of step 6), when earthquake data signal to noise ratio (S/N ratio) is low, it is 30% that data after step 5) is handled account for percentage ranges---80%, and it is 5% that the data after the data that the geological data signal to noise ratio (S/N ratio) is high and step 5) are handled account for percentage ranges---50%.

6, pre-stack hydrocarbon detection section of seismic data with low signal-to-noise ratio extracting method according to claim 1 is characterized in that step 8) is described

The empirical value of ratio be

Or get 1.5-2.5.

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