CN102156299A - Method for building anisotropic velocity model - Google Patents

Abstract

The invention relates to a method for building an anisotropic velocity model, which comprises the following steps: according to a ground earthquake CMP (corrugated metal pipe) data and aiming at small geophone offset (x/z is less than 1) data, building a conventional depth model by calculating a horizontal layer NMO (dynamic correction) velocity vnmo (0) by using the traditional NMO velocity analysis method; utilizing a big geophone offset (x/z is more than 1) data, calculating the Eta value of time domain; collecting a stratum vertical velocity vp0 by utilizing log data or VSP (vertical seismic profiling) data; calculating an anisotropic parameter delta by combining the acquired NMO velocity; acquiring a horizontal spread velocity vh by utilizing refraction seismic or well seismic data; and calculating Epsilon by utilizing the relationship between the longitudinal wave vertical velocity and horizontal velocity. By quickly and accurately acquiring NMO velocity and the anisotropic parameter by using an iteration method, a powerful technical method for researching the characteristics such as underground velocity, lithological characters, crack, and the like, is provided.

Description

The method that a kind of anisotropy rate pattern is set up

Technical field:

The invention belongs to the seismic data process field, especially a kind of method of utilizing anisotropy rate pattern deal with data.

Background technology:

Existing velocity analysis and modelling technology are based upon on isotropic basis, what adopt is hyperbolic time difference formula, even apart from relationship technology (as four item normal moveout correction technology), but do not eliminate the anisotropy influence of ball medium fully when existing process software adopts non-double curve.

Summary of the invention:

Purpose of the present invention provides a kind of anisotropic velocity analysis method that adopts in the geological data processing procedure, improve the precision of velocity analysis, and then improve image quality.

The technical solution adopted in the present invention is: the method that a kind of anisotropy rate pattern is set up, and its concrete steps are:

A, according to surface seismic CMP road set information, at little geophone offset (x/z＜1) data, utilize traditional NMO velocity analysis means to calculate acline NMO speed v _Nmo(0) sets up the conventional depth model;

B, according to surface seismic CMP road set information, utilize big geophone offset (x/z＞1) data, calculate the η value of time domain;

C, at first utilize log data or VSP data to pick up stratum vertical velocity v _P0, and calculate anisotropic parameters δ, the v here in conjunction with the NMO velograph of asking for previously _Nmo(0) can obtain by short horizontal reflection face stack velocity of arranging is approximate;

D, utilization refraction earthquake or cross-well seismic data are tried to achieve the horizontal transmission speed v _h, utilize between compressional wave vertical velocity and the horizontal velocity relation calculate ε, also can utilize formula to calculate the ε parameter model according to η value, δ value that former steps are obtained.The formula that the method that a kind of anisotropy rate pattern is set up is calculated is:

$v_{p0}=\sqrt{c_{33}/\mathrm{\ρ}}$ $\mathrm{\ϵ}=\frac{c_{11}-c_{33}}{2c_{33}}$ $\mathrm{\δ}=\frac{{(c_{13}+c_{44})}^2-{(c_{33}-c_{44})}^2}{{2c}_{33}(c_{33}-c_{44})}$

Wherein ρ is a Media density, v _P0Be the vertical speed of qP ripple in the Method in Transverse Isotropic Medium, ε, δ and be two dimensionless anisotropy factors of expression VTI medium anisotropy intensity;

$v_{\mathrm{nmo}}\left(\mathrm{\φ}\right)=\frac{v\left(\mathrm{\φ}\right)}{\cos \mathrm{\φ}}\frac{\sqrt{1+\frac{1}{v\left(\mathrm{\φ}\right)}\frac{d^{2}v}{{\mathrm{d\θ}}^2}{|}_{\mathrm{\θ}=\mathrm{\φ}}}}{1-\frac{\tan \mathrm{\φ}}{v\left(\mathrm{\φ}\right)}\frac{\mathrm{dv}}{\mathrm{d\θ}}{|}_{\mathrm{\θ}=\mathrm{\φ}}}.$

The invention has the beneficial effects as follows:

Set up technical Analysis software by the anisotropy rate pattern, with the technical barrier that solves the velocity analysis of deep seismic data.Pick up asking for of NMO speed and anisotropic parameters rapidly and accurately by process of iteration, strong technological means is provided to features such as the speed of studying underground complexity, lithology, cracks.

Description of drawings

Fig. 1 is the workflow diagram of VTI media depth migration velocity analysis of the present invention.

Fig. 2 is time domain η value model figure in the embodiment of the invention.

The anisotropy depth shift δ value of Fig. 3 for trying to achieve in the embodiment of the invention.

The anisotropy depth shift ε value of Fig. 4 for trying to achieve in the embodiment of the invention.

Fig. 5 is the road collection after isotropy in the embodiment of the invention (left side) and the skew of anisotropy (right side) rate pattern.

Fig. 6 is that Fig. 5 is the sectional view of isotropy and anisotropy velocity analysis skew in the embodiment of the invention.

Embodiment:

Describe embodiments of the invention in detail below in conjunction with accompanying drawing.

The method that a kind of anisotropy rate pattern is set up, concrete steps are:

A, according to surface seismic CMP road set information, at little geophone offset (x/z＜1) data, utilize traditional NMO velocity analysis means to calculate acline NMO speed v _Nmo(0) sets up the conventional depth model;

B, according to surface seismic CMP road set information, utilize big geophone offset (x/z＞1) data, calculate the η value of time domain;

C, at first utilize log data or VSP data to pick up stratum vertical velocity v _P0, and calculate anisotropic parameters δ, the v here in conjunction with the NMO velograph of asking for previously _Nmo(0) can obtain by short horizontal reflection face stack velocity of arranging is approximate;

D, utilization refraction earthquake or cross-well seismic data are tried to achieve the horizontal transmission speed v _h, utilize between compressional wave vertical velocity and the horizontal velocity relation calculate ε.

In the steps d, utilize formula to calculate the ε parameter model according to η value, δ value that former steps are obtained.

In the formula that calculates be:

$v_{p0}=\sqrt{c_{33}/\mathrm{\ρ}}$ $\mathrm{\ϵ}=\frac{c_{11}-c_{33}}{2c_{33}}$ $\mathrm{\δ}=\frac{{(c_{13}+c_{44})}^2-{(c_{33}-c_{44})}^2}{{2c}_{33}(c_{33}-c_{44})}$

Wherein ρ is a Media density.v _P0Be the vertical speed of qP ripple in the Method in Transverse Isotropic Medium, ε, δ and be two dimensionless anisotropy factors of expression VTI medium anisotropy intensity.

$v_{\mathrm{nmo}}\left(\mathrm{\φ}\right)=\frac{v\left(\mathrm{\φ}\right)}{\cos \mathrm{\φ}}\frac{\sqrt{1+\frac{1}{v\left(\mathrm{\φ}\right)}\frac{d^{2}v}{{\mathrm{d\θ}}^2}{|}_{\mathrm{\θ}=\mathrm{\φ}}}}{1-\frac{\tan \mathrm{\φ}}{v\left(\mathrm{\φ}\right)}\frac{\mathrm{dv}}{\mathrm{d\θ}}{|}_{\mathrm{\θ}=\mathrm{\φ}}}.$

VTI medium anisotropy velocity analysis principle is:

The character of elastic medium model determines that by elastic matrix the elastic matrix of VTI medium has been determined the relation between stress and strain, but its physical significance is very not directly perceived.Thomsen has proposed the parameter of a cover sign VTI medium elastic property, between seismic signal and the anisotropic medium parameter simple, clear and definite relation has just been arranged, and has had physical meaning comparatively clearly, is defined as follows:

$v_{p0}=\sqrt{c_{33}/\mathrm{\ρ}};$ $\mathrm{\ϵ}=\frac{c_{11}-c_{33}}{2c_{33}};$ $\mathrm{\δ}=\frac{{(c_{13}+c_{44})}^2-{(c_{33}-c_{44})}^2}{{2c}_{33}(c_{33}-c_{44})}$

Wherein ρ is a Media density.v _P0Be the vertical speed of qP ripple in the Method in Transverse Isotropic Medium, ε, δ and be two dimensionless anisotropy factors of expression VTI medium anisotropy intensity.Wherein ε is the parameter of tolerance qP ripple strength of anisotropy, and ε is big more, and the compressional wave anisotropy of medium is strong more; δ influences the parameter of qP ripple in nearly vertical speed size.Because in the anisotropic medium, P fluctuation school velometer is shown:

$v_{\mathrm{nmo}}\left(\mathrm{\φ}\right)=\frac{v\left(\mathrm{\φ}\right)}{\cos \mathrm{\φ}}\frac{\sqrt{1+\frac{1}{v\left(\mathrm{\φ}\right)}\frac{d^{2}v}{{\mathrm{d\θ}}^2}{|}_{\mathrm{\θ}=\mathrm{\φ}}}}{1-\frac{\tan \mathrm{\φ}}{v\left(\mathrm{\φ}\right)}\frac{\mathrm{dv}}{\mathrm{d\θ}}{|}_{\mathrm{\θ}=\mathrm{\φ}}}$

Therefore, in the anisotropic medium, the NMO velocity of P ripple must be subjected to v _P0, ε, the δ domination, compare the form of expression with the NMO speed in the isotropic medium complicated more.

As shown in Figure 1: VTI medium anisotropy rate pattern is set up flow process and is:

The parameter that influences surface-seismic data mainly comprises: v _P0, δ and ε, and only the data of subsurface reflective boundary can't be asked this three parameters simultaneously, utilizing surface-seismic data, log data to carry out asking for of formation anisotropy parameter jointly after deliberation just becomes the work with operability, and concrete steps are:

A, according to surface seismic CMP road set information, at little geophone offset (x/z＜1) data, utilize traditional NMO velocity analysis means to calculate acline NMO speed v _Nmo(0) sets up the conventional depth model.

B, according to surface seismic CMP road set information, utilize big geophone offset (x/z＞1) data, calculate the η value of time domain.

C, at first utilize log data or VSP data to pick up stratum vertical velocity v _P0, and calculate anisotropic parameters δ, the v here in conjunction with the NMO velograph of asking for previously _Nmo(0) can obtain by short horizontal reflection face stack velocity of arranging is approximate.

If d has refraction earthquake or cross-well seismic data to try to achieve the horizontal transmission speed v _h, can also utilize between compressional wave vertical velocity and the horizontal velocity relation calculate ε, if can't obtain compressional wave velocity of propagation in the horizontal direction, can utilize formula to calculate the ε parameter model according to η value, δ value that former steps are obtained so.So just can set up anisotropy depth shift model.

According to surface seismic CMP road set information, utilize big geophone offset (x/z＞1) data as shown in Figure 2, calculate the η value model of time domain.

Utilize electrobed data and isotropy migrated section according to formula:

Ask for the δ model, as shown in Figure 3.

Utilize formula

Ask for depth shift anisotropy ε value model, as shown in Figure 4.

Shown in the left figure of Fig. 5, be the result who adopts nearly shot point road to carry out velocity analysis, the road collection of promptly short NMO velocity skew of arranging, as can be seen on the Chang Gui normal moveout correction section, the big geophone offset of shallow-layer place lineups upwarp, anisotropy occurred,, then wasted the information that large offseting distance carries if adopt the cutting method in the conventional processing.Shown in the right figure of Fig. 5, for having adopted after the anisotropy velocity analysis method, solved the anisotropy of large offseting distance, effectively utilized large offseting distance information, from skew road collection as can be seen, the big geophone offset of shallow-layer place lineups upwarp phenomenon and have obtained good solution.

As shown in Figure 6, obtaining the consistance enhancing aspect the lineups continuity, integral energy is also strengthened, and effect is better than the former.This shows, adopt analysis of anisotropic non-double curve moveout velocity and modelling, can obviously improve imaging effect, obtain geological effect preferably.

Claims (3)

1. the method set up of an anisotropy rate pattern is characterized in that concrete steps are:

A, according to surface seismic CMP road set information, at little geophone offset (x/z＜1) data, utilize traditional NMO velocity analysis means to calculate acline NMO speed v _Nmo(0) sets up the conventional depth model;

B, according to surface seismic CMP road set information, utilize big geophone offset (x/z＞1) data, calculate the η value of time domain;

C, at first utilize log data or VSP data to pick up stratum vertical velocity v _P0, and calculate anisotropic parameters δ, the v here in conjunction with the NMO velograph of asking for previously _Nmo(0) can obtain by short horizontal reflection face stack velocity of arranging is approximate;

D, utilization refraction earthquake or cross-well seismic data are tried to achieve the horizontal transmission speed v _h, utilize between compressional wave vertical velocity and the horizontal velocity relation calculate ε.

2. the method that a kind of anisotropy rate pattern according to claim 1 is set up is characterized in that in the steps d, utilizes formula to calculate the ε parameter model according to η value, δ value that former steps are obtained.

3. the method that a kind of anisotropy rate pattern according to claim 1 is set up is characterized in that the formula that calculates is:

$v_{p0}=\sqrt{c_{33}/\mathrm{\ρ}}$ $\mathrm{\ϵ}=\frac{c_{11}-c_{33}}{2c_{33}}$ $\mathrm{\δ}=\frac{{(c_{13}+c_{44})}^2-{(c_{33}-c_{44})}^2}{{2c}_{33}(c_{33}-c_{44})}$

Wherein ρ is a Media density, v _P0Be the vertical speed of qP ripple in the Method in Transverse Isotropic Medium, ε, δ and be two dimensionless anisotropy factors of expression VTI medium anisotropy intensity;

$v_{\mathrm{nmo}}\left(\mathrm{\φ}\right)=\frac{v\left(\mathrm{\φ}\right)}{\cos \mathrm{\φ}}\frac{\sqrt{1+\frac{1}{v\left(\mathrm{\φ}\right)}\frac{d^{2}v}{{\mathrm{d\θ}}^2}{|}_{\mathrm{\θ}=\mathrm{\φ}}}}{1-\frac{\tan \mathrm{\φ}}{v\left(\mathrm{\φ}\right)}\frac{\mathrm{dv}}{\mathrm{d\θ}}{|}_{\mathrm{\θ}=\mathrm{\φ}}}.$

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