CN103576197A - Method for extracting converted wave angle channel set - Google Patents

Abstract

The invention discloses a method for extracting a converted wave angle channel set for improving the speed and precision of calculating the converted wave incidence angle in the earthquake process. A channel set, the converted wave speed and aeolotropy parameters of a converted wave are utilized for calculating the speed, the aeolotropy parameters of a longitudinal wave, the longitudinal shot-geophone distance corresponding to the converted wave shot-geophone distance, the converted wave travel time of the aero shot-geophone distance, the longitudinal wave travel time and the interlayer longitudinal wave speed, wherein the channel set is formed through longitudinal wave incidence converted wave data and transverse wave reflection converted wave data, the amplitude of the channel set changes along with the offset distance, and the normal difference of the channel set is corrected. The converted wave incidence angle theta is calculated according to the longitudinal wave time difference equation and the interlayer longitudinal wave speed, and the incidence angle of each sampling point is calculated, wherein each sampling point is placed on the angle channel of the incidence angle. The process is carried out repeatedly for all sampling points to obtain the converted wave angle channel set. According to the method, the calculation is easy to conduct, and the speed and precision of extracting the converted wave angle channel set can be improved.

Description

A kind of conversion wave angle road collection abstracting method

Technical field

The present invention relates to geophysical prospecting for oil field, specifically a kind of conversion wave angle road collection abstracting method for transformed wave AVA analysis, transformed wave kicksort and seismic properties inverting.

Background technology

In Multi-component seismic exploration, effectively utilize transformed wave information can obtain Rock Elastic Parameters more reliably.From transformed wave AVA analyzes, can extract useful lithological information, be used for predicting the medium informations such as formation lithology and crack.In transformed wave AVA equation, independent variable is transformed wave incident angle.A basic step during transformed wave AVA analyzes carries out migration in offset domain road collection to be converted to angle domain road collection exactly, carries out the calculating of transformed wave incident angle.At present, have two kinds of methods can calculate transformed wave incident angle: the one, direct projection collimation method; The 2nd, ray casting.

The former,, under the position of conversion point of known transition ripple and the condition of the reflection horizon degree of depth, asks for transformed wave incident angle with direct projection collimation method; The latter, the in the situation that of known layer speed and layer thickness, asks for transformed wave incident angle with ray casting.

The computing velocity of direct projection collimation method is fast, but the angle of its calculating is always less than normal, and error is larger; The result of calculation of ray casting is accurate, but its operand is large, and computing velocity is slow.

Summary of the invention

The object of the invention is to provide a kind of raising to calculate the speed of transformed wave incident angle and the conversion wave angle road collection abstracting method of precision.

The present invention adopts following steps to realize:

1) utilize p-wave source earthquake-wave-exciting in the wild and utilize three-component seismometer to record seismic event, the high-fidelity of the compressional wave incident gathering and transverse wave reflection (PS) converted waves data being carried out to relative amplitude preservation according to multiwave multicomponent earthquake data treatment scheme is processed, and forms normal-moveout correction (NMO) the Hou road collection of amplitude variation with Offset (AVO);

2) in transverse wave reflection (PS) converted waves data processing procedure, Negotiation speed analysis obtains transverse wave reflection (PS) transformed wave TEC time error correction (NMO) speed V _c2, vertical speed compares γ ₀, effective velocity compares γ _effwith PS transformed wave anisotropic parameters χ _eff;

3) by transverse wave reflection (PS) transformed wave TEC time error correction (NMO) speed V _c2, vertical speed compares γ ₀, effective velocity compares γ _effwith PS transformed wave anisotropic parameters χ _eff, calculate velocity of longitudinal wave V _p2with compressional wave anisotropic parameters η;

4) by transverse wave reflection (PS) transformed wave time t _c, transverse wave reflection (PS) transformed wave geophone offset x, transverse wave reflection (PS) transformed wave TEC time error correction (NMO) speed V _c2, vertical speed compares γ ₀compare γ with effective velocity _eff, calculate the compressional wave geophone offset x' corresponding with transverse wave reflection (PS) transformed wave geophone offset x;

Described transverse wave reflection (PS) transformed wave geophone offset x and compressional wave geophone offset x' have identical focus O and identical transfer point horizontal level x _c;

5) by transverse wave reflection (PS) transformed wave time t _c, transverse wave reflection (PS) transformed wave geophone offset x, transverse wave reflection (PS) transformed wave TEC time error correction (NMO) speed V _c2, vertical speed compares γ ₀, effective velocity compares γ _effwith PS transformed wave anisotropic parameters χ _eff, the transformed wave whilst on tour t of calculating zero shot-geophone distance _c0;

6) by the transformed wave whilst on tour t of zero shot-geophone distance _c0compare γ with vertical speed ₀calculate the compressional wave whilst on tour t of zero shot-geophone distance _p0;

7) by the compressional wave whilst on tour t of zero shot-geophone distance _p0, velocity of longitudinal wave V _p2, compressional wave anisotropic parameters η and compressional wave geophone offset x' obtain compressional wave time difference equation t _p;

8) by the compressional wave whilst on tour t of zero shot-geophone distance _p0with velocity of longitudinal wave V _p2obtain interlayer velocity of longitudinal wave V _int;

9) by compressional wave time difference equation t _pwith interlayer velocity of longitudinal wave V _int, by ray parameter method, calculate PS transformed wave incidence angle θ;

10) calculate the incident angle of each sampling point in transverse wave reflection (PS) converted waves data, this sampling point is placed on the angle road of incident angle, all sampling points are repeated to this process, obtain transverse wave reflection (PS) conversion wave angle road collection.

The present invention easily realizes, and the results show has improved speed and the precision that extracts conversion wave angle road collection.

Accompanying drawing explanation

Fig. 1 is that transformed wave incident angle is calculated schematic diagram, longitudinal wave reflection in figure: the incident of P ripple, P wave reflection; PS transformed wave reflection: the incident of P ripple, S wave reflection;

Fig. 2 is transformed wave geophone offset road collection, and in figure, the longitudinal axis is the time, and unit second, transverse axis is Taoist monastic name, and track pitch is 100 meters, and offset distance is 0 meter;

Fig. 3 is the incident angle result contrast that distinct methods calculates, and according to the transformed wave speed data in table 1, is respectively the result of incident angle at the different depth interface of 1000 meters with the transformed wave geophone offset of the present invention, ray-tracing scheme and the calculating of direct projection collimation method;

Fig. 4 is conversion wave angle road collection, and in figure, the longitudinal axis is the time, and unit second, transverse axis is angle Taoist monastic name, angle step 5 degree, and first is 0 degree.

Embodiment

The present invention is mapped as corresponding compressional wave geophone offset, whilst on tour and speed by transforming by transformed wave geophone offset, whilst on tour and speed, asks for the incident angle of transformed wave by the ray parameter method of compressional wave.As shown in Figure 1, the transformed wave incident angle that geophone offset is x is that θ equals the incident compressional angle θ that geophone offset is x', by calculating the incident compressional angle θ that geophone offset is x', and the transformed wave incidence angle θ that to have obtained geophone offset be x.

The concrete implementation step of the present invention is as follows:

1) utilize p-wave source earthquake-wave-exciting in the wild and utilize three-component seismometer to record seismic event, the high-fidelity of the compressional wave incident gathering and transverse wave reflection (PS) converted waves data being carried out to relative amplitude preservation according to multiwave multicomponent earthquake data treatment scheme is processed, and forms normal-moveout correction (NMO) the Hou road collection (Fig. 2) of amplitude variation with Offset (AVO);

2) in PS converted waves data processing procedure, by being carried out to velocity analysis, several collection of PS transformed wave obtains PS transformed wave speed file (table 1), and this file comprises the PS transformed wave time t of zero shot-geophone distance _c0, PS transformed wave TEC time error correction (NMO) speed V _c2, vertical speed compares γ ₀, effective velocity compares γ _effwith transformed wave anisotropic parameters χ _eff;

Table 1

t C0(s)	V C2(m/s)	γ 0	γ eff	χ eff
					0.6749	2481.9492	1.8414	1.8414	0.0000
0.9624	2616.9590	1.8358	1.8345	0.0203
					1.2174	2763.6016	1.8149	1.8059	0.0417
1.4655	2870.5964	1.8007	1.7887	0.0480
					1.7096	2951.6274	1.7880	1.7744	0.0483
2.0572	3063.4771	1.7654	1.7472	0.0493

3) by PS transformed wave TEC time error correction (NMO) speed V _c2, vertical speed compares γ ₀, effective velocity compares γ _effwith PS transformed wave anisotropic parameters χ _eff, calculate velocity of longitudinal wave V _p2with compressional wave anisotropic parameters η;

$V_{P2}^2=V_{C2}^2\frac{{\mathrm{\γ}}_{\mathrm{eff}}(1+{\mathrm{\γ}}_0)}{1+{\mathrm{\γ}}_{\mathrm{eff}}}---\left(1\right)$

$\mathrm{\η}=\frac{{\mathrm{\χ}}_{\mathrm{eff}}}{({\mathrm{\γ}}_0-1){\mathrm{\γ}}_{\mathrm{eff}}^2}---\left(2\right)$

4) by PS transformed wave time t _c, PS transformed wave geophone offset x, PS transformed wave TEC time error correction (NMO) speed V _c2, vertical speed compares γ ₀compare γ with effective velocity _eff, calculate the compressional wave geophone offset x' corresponding with PS transformed wave geophone offset x;

In Fig. 1, x is the geophone offset of PS transformed wave, transfer point horizontal level x _ccomputing formula be,

$x_C=x(c_0+\frac{c_2{x}^2}{1+c_3{x}^2}),---\left(3\right)$

Wherein, c ₃=c ₂/ (1-c ₀), coefficient c ₀and c ₂expression formula be,

$c_0=\frac{{\mathrm{\&gamma;}}_{\mathrm{<figure-callout\; id="1"\; label="eff"\; filenames="HDA00001964814100012.png"\; state="\{\{state\}\}">eff</figure-callout>}}}{1+{\mathrm{\&gamma;}}_{\mathrm{eff}}},---\left(4\right)$

$c_2=\frac{{\mathrm{\&gamma;}}_{\mathrm{eff}}(1+{\mathrm{\&gamma;}}_0)({\mathrm{\&gamma;}}_0{\mathrm{\&gamma;}}_{\mathrm{eff}}-1)}{2t_{C2}^2{V}_{C2}^2{\mathrm{\&gamma;}}_0{\left({1+\mathrm{\&gamma;}}_{\mathrm{eff}}\right)}^3}.---\left(5\right)$

By transfer point horizontal level x _ccalculate corresponding compressional wave geophone offset x', x' and x _crelation as follows,

x'＝2x _C。(6)

Described PS transformed wave geophone offset x and compressional wave geophone offset x' have identical focus O and identical transfer point horizontal level x _c;

5) by PS transformed wave time t _c, PS transformed wave geophone offset x, PS transformed wave TEC time error correction (NMO) speed V _c2, vertical speed compares γ ₀, effective velocity compares γ _effwith PS transformed wave anisotropic parameters χ _eff, the transformed wave whilst on tour t of calculating zero shot-geophone distance _c0;

$t_C^2\left(x\right)=t_{C0}^2+\frac{x^2}{V_{C2}^2}+\frac{A_4{x}^4}{1+A_5{x}^2},---\left(7\right)$

$A_4=-\frac{{({\mathrm{\&gamma;}}_0{\mathrm{\&gamma;}}_{\mathrm{eff}}-1)}^2+8(1+{\mathrm{\&gamma;}}_0){\mathrm{\&gamma;}}_{\mathrm{eff}}}{{4t}_{C0}^2{V}_{C2}^4{\mathrm{\&gamma;}}_0{(1+{\mathrm{\&gamma;}}_{\mathrm{eff}})}^2},---\left(8\right)$

$A_5=\frac{A_4{V}_{C2}^2(1+{\mathrm{\&gamma;}}_0){\mathrm{\&gamma;}}_{\mathrm{eff}}[({\mathrm{\&gamma;}}_0-1){\mathrm{\&gamma;}}_{\mathrm{eff}}^2+2{\mathrm{\&chi;}}_{\mathrm{eff}}]}{({\mathrm{\&gamma;}}_0-1){\mathrm{\&gamma;}}_{\mathrm{eff}}^2(1-{\mathrm{\&gamma;}}_0{\mathrm{\&gamma;}}_{\mathrm{eff}})-2(1+{\mathrm{\&gamma;}}_0){\mathrm{\&gamma;}}_{\mathrm{eff}}{\mathrm{\&chi;}}_{\mathrm{eff}}}.---\left(9\right)$

6) by the PS transformed wave whilst on tour t of zero shot-geophone distance _c0compare γ with vertical speed ₀calculate the compressional wave whilst on tour t of zero shot-geophone distance _p0;

$t_{P0}=\frac{t_{C0}}{1+{\mathrm{\&gamma;}}_0},---\left(10\right)$

7) by the compressional wave whilst on tour t of zero shot-geophone distance _p0, velocity of longitudinal wave V _p2, compressional wave anisotropic parameters η and compressional wave geophone offset x' obtain compressional wave time difference equation t _p;

$t_P^2\left(x\right)=t_{P0}^2+\frac{x^{\&prime;2}}{V_{P2}^2}-\frac{{2\mathrm{\&eta;x}}^{\&prime;4}}{V_{P2}^2[t_{p0}^2{V}_{P2}^2+(1+2\mathrm{\&eta;})x^{\&prime;2}]},---\left(11\right)$

8) by the compressional wave whilst on tour t of zero shot-geophone distance _p0with velocity of longitudinal wave V _p2, by velocity of longitudinal wave V between Dix formula computation layer _int;

9) by compressional wave time difference equation t _pwith interlayer velocity of longitudinal wave V _int, by ray parameter method, calculating incident compressional angle θ, formula is as follows,

$\mathrm{\&theta;}={\sin }^{-1}\left(\frac{{\mathrm{dt}}_p}{\mathrm{dx}}{V}_{\mathrm{int}}\right),---\left(12\right)$

Incident compressional angle θ, i.e. PS transformed wave incidence angle θ;

According to implementation step, calculate vertical wave propagation velocity, geophone offset and whilst on tour, obtain the incident angle of the transformed wave of every one deck.Fig. 3 is the incident angle result contrast of transformed wave geophone offset calculating of three kinds of distinct methods while being x=1000 rice.The first is result of the present invention, the result that the second is ray casting, and the third is the result of direct projection collimation method.From result, computational accuracy and the ray casting of result of the present invention are suitable, and the precision of direct projection collimation method result is poor.

10) calculate the incident angle of each sampling point in PS converted waves data, this sampling point is placed on the angle road of incident angle, all sampling points are repeated to this process, obtain PS conversion wave angle road collection, see Fig. 4.

According to the incident angle of calculating, the conversion radio frequency channel collection of Fig. 2 is extracted to road, angle collection and calculate, obtained conversion wave angle road collection, see Fig. 4.From result, the present invention can accurately calculate transformed wave incident angle, obtains changing wave angle road collection.Computing velocity of the present invention is very fast, and computational accuracy is high.

Claims (1)

1. change a wave angle road collection abstracting method, feature is to adopt following steps to realize:

1) utilize p-wave source earthquake-wave-exciting in the wild and utilize three-component seismometer to record seismic event, the high-fidelity of the compressional wave incident gathering and transverse wave reflection converted waves data being carried out to relative amplitude preservation according to multiwave multicomponent earthquake data treatment scheme is processed, and forms the normal-moveout correction Hou road collection of amplitude variation with Offset;

2) in transverse wave reflection converted waves data processing procedure, Negotiation speed analysis obtains transverse wave reflection transformed wave TEC time error correction speed V _c2, vertical speed compares γ ₀, effective velocity compares γ _effwith transverse wave reflection transformed wave anisotropic parameters χ _eff;

3) by transverse wave reflection transformed wave TEC time error correction speed V _c2, vertical speed compares γ ₀, effective velocity compares γ _effwith transverse wave reflection transformed wave anisotropic parameters χ _eff, calculate velocity of longitudinal wave V _p2with compressional wave anisotropic parameters η;

4) by transverse wave reflection transformed wave time t _c, transverse wave reflection transformed wave geophone offset x, transverse wave reflection transformed wave TEC time error correction speed V _c2, vertical speed compares γ ₀compare γ with effective velocity _eff, calculate the compressional wave geophone offset x' corresponding with transverse wave reflection transformed wave geophone offset x;

Described transverse wave reflection transformed wave geophone offset x and compressional wave geophone offset x' have identical focus O and identical transfer point horizontal level x _c;

5) by transverse wave reflection transformed wave time t _c, transverse wave reflection transformed wave geophone offset x, transverse wave reflection transformed wave TEC time error correction speed V _c2, vertical speed compares γ ₀, effective velocity compares γ _effwith transverse wave reflection transformed wave anisotropic parameters χ _eff, the transformed wave whilst on tour t of calculating zero shot-geophone distance _c0;

6) by the transverse wave reflection transformed wave whilst on tour t of zero shot-geophone distance _c0compare γ with vertical speed ₀calculate the compressional wave whilst on tour t of zero shot-geophone distance _p0;

7) by the compressional wave whilst on tour t of zero shot-geophone distance _p0, velocity of longitudinal wave V _p2, compressional wave anisotropic parameters η and compressional wave geophone offset x' obtain compressional wave time difference equation t _p;

8) by the compressional wave whilst on tour t of zero shot-geophone distance _p0with velocity of longitudinal wave V _p2obtain interlayer velocity of longitudinal wave V _int;

9) by compressional wave time difference equation t _pwith interlayer velocity of longitudinal wave V _int, by ray parameter method, calculate transverse wave reflection transformed wave incidence angle θ;

10) calculate the incident angle of each sampling point in transverse wave reflection converted waves data, this sampling point is placed on the angle road of incident angle, all sampling points are repeated to this process, obtain transverse wave reflection conversion wave angle road collection.

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