CN104005760B - Based on the crack detection method of azimuthal anisotropy elastic impedance - Google Patents

Abstract

The present invention is based on the crack detection method of azimuthal anisotropy elastic impedance. Taking the elastic impedance equation of Connolly and Ruger equation as basis, calculation of elastic impedance in anisotropic media and fracture parameters are derived, the dominance relation formula of fracture spacing and fracture orientation. Set up a set of crack inverting flow process based on elastic impedance, and anisotropic parameters information has been added in the Log-constrained of inverting. The method is carried out to numerical model test, and inversion result and theoretical value are roughly the same, and the fracture spacing of inverting demonstrates stronger noise immunity. Advantage of the present invention is to utilize calculation of elastic impedance in anisotropic media to ask for fracture spacing and fracture orientation simultaneously, has good effect in real data, has stronger practicality.

Description

Based on the crack detection method of azimuthal anisotropy elastic impedance

Technical field

The invention belongs to petroleum exploration field, relate in fracture reservoir overall merit and utilize elastic impedance orientation each The method that heterotropic feature detects effective fracture.

Background technology

Slit formation reservoir accounts for greatly 1/3rd of world's oil and gas reserves. As hydrocarbon migration channel with preserve sky Between, fracture detection is significant for finding oil-bearing reservoir. The research in crack is also current era storage The important step that layer is evaluated and predicted. And elastic impedance in seismic wave the reservoir in crack have orientation respectively to The feature of the opposite sex, therefore can utilize this character fracture detection. Within 1999, Connolly proposes elasticity resistance first Anti-concept, the approximate reflectance factor that he utilizes Aki&Richards to propose has been derived under isotropic medium Elastic impedance formula (Connolly, 1999), this formula has contacted log and petrophysical parameter Come, improved reservoir prediction precision. But extensively there is anisotropy in underground medium, a little less than Thomsen thinks The impact of anisotropy factor cannot be ignored, and therefore, many scholars carry out on the basis of this formula The research of the elastic impedance based in direction anisotropy medium situation, as Martins takes the lead in broad sense In Thomsen type anisotropic parameters system, proposed calculation of elastic impedance in anisotropic media concept (Martins, 2002), and by numerical model the impedance of anisotropic medium Elastic has been described with incidence angle and azimuthal Change, and the relation of the longitudinal wave reflection coefficient in Connolly formula and elastic impedance is extended to HTI medium In, obtain the compressional wave elastic impedance formula relevant with orientation, emphasize azimuthal anisotropy in elastic impedance Importance. Chen Tiansheng (2006) etc. are for too complicated the lacking of Martins calculation of elastic impedance in anisotropic media parameter Put the compressional wave elastic impedance formula of the HTI medium of again having derived. Yuan Shujin etc. (2006) propose from Shuey Set out based on P wave reflection coefficient approximate expression under VTI medium, derived weak anisotropy elastic impedance equation. Longitudinal wave reflection coefficient approximate expression under the VTI medium that Li Aishan etc. (2008) propose based on Ruger, also derives An elastic impedance equation in VTI medium, has carried out standardization to equation, has eliminated equation dimension with angle The deficiency changing and change, and by numerical simulation, carried out and from elastic impedance data volume, extracted rock thing The method research of property parameter. Introduce the general pass between longitudinal wave reflection coefficient and elastic impedance under HTI medium below Be formula:

Reflectance factor approximate equation (Ruger, 1998) in the HTI medium that given first is proposed by Ruger,

When incidence angle i hour:

$R(i,\mathrm{\φ})=\frac{1}{2}\frac{\mathrm{\ΔZ}}{Z}+\frac{1}{2}\{\frac{\mathrm{\Δ\α}}{\mathrm{\α}}-{\left(\frac{2\mathrm{\β}}{\mathrm{\α}}\right)}^2\frac{\mathrm{\ΔG}}{\mathrm{\α}}+[{\mathrm{\Δ\δ}}^V+2{\left(\frac{2\mathrm{\β}}{\mathrm{\α}}\right)}^2\mathrm{\Δ\γ}\left]\cos \mathrm{\Φ}\right\}{\sin }^{2}i---\left(1\right)$

Wherein α, β are P-wave And S speed, σ^(V), γ is Thomsen parameter, Φ=ф-ф_S, ф is Azimuth, ф_SFor the fracture orientation that inverting obtains, i is incidence angle. Wave impedance when compressional wave vertical incidence Z=ρα；α=(α₁+α₂)/2，ΔZ=Z₂-Z₁, tangential modulus G=ρ β²，β=(β₂-β₁)/2，ΔG=G₂-G₁。

Here can regard the longitudinal wave reflection coefficient in HTI medium as isotropism reflection R,^iso(i) with each Anisotropy reflection R^ani(i, φ) sum, that is,

R(i,φ)=R^iso(i)+R^ani(i,φ)(2)

Under the isotropic medium that Connolly proposes, elastic wave impedance (EI) formula is:

EI(i)=α^(1+sin2i)β^-8K2sin2iρ^1-4K2sin2i(3)

Wherein, ρ is density; K=beta/alpha is transverse and longitudinal wave velocity ratio, gets the mean value of adjacent layer.

By the relational expression between isotropism longitudinal wave reflection coefficient and elastic wave impedance, and Martins derivation The relational expression of longitudinal wave reflection coefficient and elastic impedance under HIT medium:

$R^{\mathrm{iso}}\left(i\right)=\frac{1}{2}\frac{\mathrm{\ΔEI}\left(i\right)}{\mathrm{EI}\left(i\right)}=\frac{1}{2}\mathrm{\Δ}1n\left(\mathrm{EI}\left(i\right)\right),R(i,\mathrm{\φ})=\frac{1}{2}\frac{\mathrm{\ΔEI}(i,\mathrm{\φ})}{\mathrm{EI}(i,\mathrm{\φ})}=\frac{1}{2}\mathrm{\Δ}1n\left(\mathrm{EI}(i,\mathrm{\φ})\right)---\left(4\right)$

Can set up following relational expression:

△lnEI(i,φ)=△lnEI(i)+2R^ani(i,φ)(5)

Thus, can be by the data of isotropic elasticity impedance EI (i) and calculation of elastic impedance in anisotropic media EI (i, φ) Body, asks for anisotropic emission coefficients R^ani(i, φ), and then try to achieve anisotropic parameters. General algorithm can be with Thomsen type anisotropic parameters system, for solving target, can cause equation comparatively complicated like this, and parameter is more, In numerical model, can obtain certain effect, but be difficult in actual applications accurately solve. The more important thing is, In actual production, we generally utilize fracture spacing and trend etc. intuitively anisotropic parameters as prediction The foundation in crack, and above-mentioned algorithm is not set up this type of dominant expression of fracture parameters and elastic impedance intuitively Formula, is therefore unfavorable for actual FRACTURE PREDICTION work.

Summary of the invention

Reflectance factor in the HTI medium that the elastic impedance that the present invention derives in conjunction with Connolly and Ruger propose Approximate equation, has set up the dominant table between elastic impedance and fracture parameters (fracture spacing and fracture orientation) Reach formula. Utilize prestack road, orientation collection, in conjunction with well logging, rock physics and conventional AVOZ inversion result are as constraint Condition, carries out the inverting of azimuthal anisotropy elastic impedance. In conjunction with isotropic elasticity impedance, finally ask again Solution obtains density and the fracture orientation information in crack. The method has improved the reality of elastic impedance in fracture detection Border using value.

It is as follows that the present invention realizes the concrete scheme of above-mentioned purpose:

Based on the crack detection method of azimuthal anisotropy elastic impedance, it is characterized in that, comprise the steps: Step 1: to seismic data point orientation processing (comprise and protect width migration processing), extract a point orientation and reflect altogether Point CRP(CommonReflectionPoint) road collection;

Step 2: obtain fracture parameters, fracture spacing B from conventional AVOZ inversion result^aniAnd fracture azimuth ф_S, in conjunction with well logging and rock physics information, use fracture parameters and calculation of elastic impedance in anisotropic media EI's (i, φ) is dominant Relational expression, simulates the calculation of elastic impedance in anisotropic media Log-constrained curve under different azimuth road collection;

Step 3: implement the Sparse Pulse Inversion of well constraint in Jason software, trying to achieve road, each point of orientation set pair should Calculation of elastic impedance in anisotropic media EI (i, φ), ф for gather azimuth;

Step 4: divide incidence angle processing to seismic data, comprise and protect width migration processing, obtain incidence angle part folded Add collection;

Step 5: utilize different incidence angles stack road collection, in Jason software, implement the Sparse Pulse Inversion of well constraint, Ask for isotropic elastic impedance EI (i), i is incidence angle;

Step 6: calculate the ratio of calculation of elastic impedance in anisotropic media EI (i, φ) and isotropic elasticity impedance EI (i), use inverting Algorithm is asked for fracture spacing B^aniAnd fracture azimuth ф_S；

Step 7: prediction fracture reservoir development belt.

The beneficial effect that the present invention compares prior art generation is:

Crack is the reservoir space of oil gas, is again the migration pathway of fluid, and fracture detection is to finding oil gas storage Layer is significant. The identification in crack is current study hotspot and difficult point.

1, the present invention proposes a kind of in HTI medium the fracture parameters based on azimuthal anisotropy elastic impedance Inversion method. Taking the elastic impedance equation of Connolly and Ruger equation as basis, derived respectively to The dominance relation formula of opposite sex elastic impedance and fracture parameters (fracture spacing and fracture orientation).

2, the present invention has set up a set of crack inverting flow process based on orientation elastic impedance, and will be by conventional AVOZ The anisotropic parameters information that inverting obtains adds in the Log-constrained of inverting. The method is carried out to numerical model Test, inversion result and theoretical value are roughly the same, and the fracture spacing of inverting demonstrates stronger noise immunity. ? In real data test, inversion result and FMI imaging logging data coincidence are higher.

3, advantage of the present invention is to utilize calculation of elastic impedance in anisotropic media to ask for fracture spacing and crack side simultaneously Position, and in real data, have good effect, there is stronger practicality.

Brief description of the drawings

Fig. 1 is the fracture parameters inverting flow chart based on azimuthal anisotropy elastic impedance;

Fig. 2 (a) is the comprehensive collection schematic diagram of single CRP point in numerical model data;

Fig. 2 (b) is HTI dielectric model schematic diagram in numerical model data;

Fig. 3 is the fracture spacing B that does not add noise inverting in numerical model^aniAnd fracture azimuth ф_SWith theoretical value Comparison diagram;

Fig. 4 (a-f) is that in numerical model, signal to noise ratio is respectively 10,8, the crack of inverting in 5,3,2,1 o'clock Density B^aniWith theoretical value comparison diagram;

Fig. 5 is that in numerical model, signal to noise ratio is respectively 10,8, the fracture azimuth of inverting in 5,3,2,1 o'clock ф_SWith theoretical value comparison diagram;

Fig. 6 is Xinjiang block different azimuth calculation of elastic impedance in anisotropic media Log-constrained curve map;

Fig. 7 is calculation of elastic impedance in anisotropic media inversion result figure under this block different azimuth of Xinjiang;

Fig. 8 is fracture spacing orientation and the well data comparison diagram that this block of Xinjiang is crossed well A inverting;

Fig. 9 is fracture spacing orientation and the well data comparison diagram that this block of Xinjiang is crossed well B inverting;

Figure 10 is the superimposed plane of fracture spacing and orientation and the well of a room group inverting of this block of Xinjiang C, D, the partial enlarged drawing at E place.

Detailed description of the invention

Below in conjunction with embodiment and accompanying drawing, the present invention will be further described.

Fig. 1 is the flow chart of the fracture parameters inversion method based on azimuthal anisotropy elastic impedance in the present invention: Step 1: to seismic data point orientation processing (comprise and protect width migration processing), extract a point orientation and reflect altogether Point CRP(CommonReflectionPoint) road collection;

Step 2: obtain fracture parameters (fracture spacing B from conventional AVOZ inversion result^aniAnd fracture azimuth ф_S), in conjunction with well logging and rock physics information, the fracture parameters of deriving with the present invention and anisotropic elasticity resistance The dominance relation formula of anti-EI (i, φ), simulates the calculation of elastic impedance in anisotropic media Log-constrained song under different azimuth road collection Line;

Step 3: implement the Sparse Pulse Inversion of well constraint in Jason software, trying to achieve road, each point of orientation set pair should Calculation of elastic impedance in anisotropic media EI (i, φ), ф for gather azimuth;

Step 4: to seismic data point incidence angle processing (comprise and protect width migration processing), obtain angle (incident Angle) partial stack road collection;

Step 5: utilize different incidence angles stack road collection, in Jason software, implement the Sparse Pulse Inversion of well constraint, Ask for isotropic elastic impedance EI (i), i is incidence angle;

Step 6: calculate the ratio of calculation of elastic impedance in anisotropic media EI (i, φ) and isotropic elasticity impedance EI (i), with this Bright inversion algorithm is asked for fracture spacing B^aniAnd fracture azimuth ф_S；

Step 7: prediction fracture reservoir development belt.

Calculation of elastic impedance in anisotropic media Log-constrained curve in described step 2, proposes based on Ruger Reflectance factor approximate equation in HTI medium and the elastic impedance equation of Connolly, foundation respectively to different Property elastic impedance and fracture parameters, fracture spacing B^aniAnd fracture azimuth ф_SBetween Explicit functions intend Close out. Wherein, p-and s-wave velocity, density is obtained by log data, and fracture parameters is by conventional AVOZ inverting Result obtains.

The described fracture parameters inversion method based on azimuthal anisotropy elastic impedance, be combine utilize each to Same sex elastic impedance and calculation of elastic impedance in anisotropic media are asked for fracture spacing B simultaneously^aniAnd fracture azimuth ф_S。

The described fracture parameters inversion method based on azimuthal anisotropy elastic impedance, at actual data application In the scope of application as follows: the incident angle in angle-incidence angle partial stack data is little, is generally less than 30 Degree; The fracture spacing of surveying in the present invention, refers to the strength of anisotropy that effective fracture causes. Effectively so-called Crack referred to open and filling the crack of fluid, be effective reservoir space of oil, gas, water. Anisotropy Intensity is the coefficient result in many group cracks: in the time that effective fracture within the scope of certain depth moves towards roughly the same, Anisotropic degree is high; Otherwise if in certain depth bounds, the trend in crack presents different sides To, the anisotropic character of seismic wave can be weakened, even can demonstrate isotropic feature, and this is with regard to nothing Method obtains the information of subterranean fracture by inverting.

The general principle based on azimuthal anisotropy elastic impedance fracture detection method providing in the present invention as Under: in the relational expression of isotropism, calculation of elastic impedance in anisotropic media and anisotropic emission coefficient, i.e. formula (5) On basis, improve.

Fracture spacing formula by defining in Ruger equation:

$B^{\mathrm{ani}}=\frac{1}{2}[{\mathrm{\Δ\δ}}^V+2{\left(2K\right)}^2\mathrm{\Δ\γ}]---\left(6\right)$

Substitution anisotropic emission coefficients R^aniIn (i, φ), formula (5) can be rewritten into:

△lnEI(i,φ)=△lnEI(i)+2B^anicos²(φ-φ_s)sin²i(7)

And then obtain isotropism, calculation of elastic impedance in anisotropic media and fracture spacing B^ani, fracture azimuth ф_S's Dominance relation formula

EI(i,φ)/EI(i)=exp(2B^anicos²(φ-φ_s)sin²i)(8)

The present invention asks for fracture spacing B^aniAnd fracture azimuth ф_STime according to following equation group:

$\left\{\begin{array}{c}1n(\mathrm{EI}(i,\mathrm{\φ})/\mathrm{EI}\left(i\right))=C_1{\cos }^2\mathrm{\φ}{\sin }^{2}i+2C_2\sin \mathrm{\φ}\cos \mathrm{\φ}{\sin }^{2}i+C_3{\sin }^2\mathrm{\φ}{\sin }^{2}i\\ C_1=B^{\mathrm{ani}}{\cos }^2{\mathrm{\φ}}_s\\ C_2{B}^{\mathrm{ani}}{\sin }^2{\mathrm{\φ}}_s\\ C_3{B}^{\mathrm{ani}}{\sin }^2{\mathrm{\φ}}_s\end{array}\right.---\left(9\right)$

Solve above formula overdetermination system of linear equations, obtain C₁，C₂，C₃, have:

B^ani=C₁+C₃，φ_s=arctan(2C₃/C₂)(10)

In the present invention, the scope of application of fracture detection is as follows: the incident angle in incidence angle partial stack data is little (being generally less than 30 degree); The fracture spacing of surveying in the present invention, refers to that the anisotropy that effective fracture causes is strong Degree. So-called effective fracture referred to open and filling the crack of fluid, be oil, gas, water effectively preserve sky Between. In the time that effective fracture moves towards roughly the same, show stronger anisotropic character, use this algorithm passable Effectively survey; In the time that effective fracture moves towards different, show weak anisotropic character, this algorithm can not have Effect is surveyed.

Fig. 2 is numerical model design data, and wherein (a) is the comprehensive acquisition system of single CRP point, regulation Directions X is 0 degree, and angle increases clockwise, is total to azimuth is divided into altogether 6 orientation by one of 30 degree Angle Dao Ji. (b) be double-deck single Interface Crack model, upper strata A is homogeneous isotropic medium layer, the B of lower floor For HTI fracture medium layer. The context parameter of each layer of medium and layer thickness are as table 1.

The background velocity of table 1 medium and layer thickness

(note: speed unit: meter per second; Density unit: kilograms per cubic meter; Thickness unit: rice)

Design one and comprise the survey line that 41 CRP are ordered. The from the 1st to the 41st CRP point, characterizes each to different Three coefficients of property are given as successively: ε^V=-0.2，γ^V=0，n=0～0.39，δ^V=n². Utilize Ruger public affairs Formula can be calculated the fracture spacing on each CRP, and the azimuth of designing this list group crack is 90 degree.

Fig. 3 is the fracture spacing B that does not add noise inverting in numerical model^aniAnd fracture azimuth ф_SWith theoretical value Contrast, fracture spacing changes line as shown in blue solid lines in figure with No. CRP. Can find out from CRP1～CRP41, Fracture spacing is conic section to be increased. And red dispersion point is inverting value. When data noiselessness, the crack of inverting Density fits like a glove with CRP change curve with the fracture spacing of just drilling from CRP1～CRP41, has confirmed to make an uproar in nothing In sound situation, the accuracy of this inversion algorithm and reliability.

In Fig. 4, a-f is for having added after certain noise, and signal to noise ratio is respectively 10,8, and 5,3,2,1 o'clock anti- The fracture spacing of drilling and theoretical value contrast. Under different state of signal-to-noise, the noise immunity of fracture spacing is stronger, anti- Drill result all near theoretical curve, along with the increase of signal to noise ratio, the inversion result degree of accuracy improves gradually, when Signal to noise ratio is 10 o'clock, and inverting value and theoretical value are substantially identical.

Fig. 5 is that in numerical model, signal to noise ratio is respectively 10,8, the fracture orientation of inverting in 5,3,2,1 o'clock with Theoretical value contrast, compares and fracture spacing, the noise immunity of fracture orientation a little less than, in the time that signal to noise ratio is less than 5, More than 50% CRP point tolerance is all larger; Be greater than at 5 o'clock, CRP point and the theoretical value goodness of fit are higher, only have few Part singular value point. Therefore, when data signal to noise ratio is higher, the fracture orientation of inverting just more accurately and reliably, and No matter fracture spacing is at anti-noise ability, or in the inverting degree of accuracy, is all more better than fracture orientation.

Fig. 2～Fig. 5 illustrates in numerical model, the fracture detection method based on azimuthal anisotropy elastic impedance Can effectively ask for fracture spacing and fracture orientation, and the fracture spacing of inverting demonstrates stronger noise immunity.

The reality that is applied as example and illustrates the method in the block real data of Xinjiang with this algorithm below

Border effect.

Fig. 6 is calculation of elastic impedance in anisotropic media Log-constrained curve under different azimuth. 4 curves that show in figure Corresponding orientation is respectively 23 degree, 53 degree, 83 degree, 113 degree. This is to be incorporated into firing angle, azimuth information, The fracture spacing and the bearing data that are obtained by conventional AVOZ inverting, and well logging in velocity of longitudinal wave, shear wave Speed, density, the dominance relation formula of the fracture parameters of deriving according to the present invention and calculation of elastic impedance in anisotropic media, Calculation of elastic impedance in anisotropic media Log-constrained curve under the different azimuth road collection simulating. When incidence angle or orientation When angle is different, elastic impedance value can produce the difference in magnitude, and therefore, we introduce Whitcombe couple The normalized thought of Connolly elastic equation (Whitcombe, etal., 2002), by different elastic impedances Be grouped under same dimension. What in figure, show is standardization result afterwards, and the approximate trend of curve is identical, but At target zone section, at the bottom of pushing up a room group from a room group, curve difference is comparatively obvious, changes more Acutely, this is to cause because this section exists stronger anisotropic character. Therefore, than tradition side Method, this elastic impedance matching mode has better retained the feature of Reservoir anisotropy, has better followed Algorithm principle, makes to calculate more accurately credible.

Fig. 7 is calculation of elastic impedance in anisotropic media inversion result under this block different azimuth of Xinjiang. Under different azimuth Elastic impedance has shown obvious difference, has embodied the effect of anisotropy Log-constrained.

Fig. 8 is fracture spacing orientation and the contrast of well data that this block of Xinjiang is crossed well A inverting. Conventional logging money Material shows, at group layer position place, a room, fracture porosity is higher, and imaging logging data show that this position is grown and split Seam type carbonate rock, and be single group crack. Contrast inversion result can be found out, the crack of this layer of position place's inverting It is abnormal that density is high value, matches with log data; In the crack polar plot of inverting, direction of arrow representative is split Seam trend, length and bin shade represent density height, the fracture orientation of inverting that hence one can see that is 3 Degree; Meanwhile, the rose diagram of imaging logging statistics has shown the trend in target location crack, red direction of principal axis generation Table fracture strike, length represents fracture spacing height. Contrast knownly, the fracture orientation of inverting and FMI show Fracture strike consistent.

Fig. 9 is fracture spacing orientation and the contrast of well data that this block of Xinjiang is crossed well B inverting. B well is in target Group place, a room of reservoir fracture porosity is lower, and imaging logging shows free from flaw; In inversion result, crack is close Degree is a little less than target location shows, and similar to background value, without abnormal show, and crack polar plot also shows This place, without anisotropic character, all matches with log data.

Figure 10 is the superimposed plane of fracture spacing and orientation and the well of a room group inverting of this block of Xinjiang C, D, the partial enlarged drawing at E place. Single group crack is all grown at three mouthfuls of well location places in figure, and the fracture spacing of inverting also Demonstrate relatively high value. In the fracture orientation of inverting, well H601-4, H601-14, H601-5 and reality Move towards substantially identical. Known by above-mentioned analysis, based on azimuthal anisotropy elastic impedance crack inversion method Can ask for comparatively accurately fracture spacing and orientation, there is stronger practicality.

Claims (5)

1. the crack detection method based on azimuthal anisotropy elastic impedance, is characterized in that, described method bag Draw together following steps:

Step 1: divide orientation processing to seismic data, comprise and protect width migration processing, extract a point orientation common reflection point CRP road collection;

Step 2: obtain fracture parameters in conjunction with well logging and rock physics information from conventional AVOZ inversion result, use The dominance relation formula of fracture parameters and calculation of elastic impedance in anisotropic media EI (i, φ), simulates each under different azimuth road collection Anisotropy elastic impedance Log-constrained curve, described fracture parameters is fracture spacing B^aniAnd fracture azimuth ф_S； Step 3: implement the Sparse Pulse Inversion of well constraint in Jason software, trying to achieve road, each point of orientation set pair should Calculation of elastic impedance in anisotropic media EI (i, φ), ф for gather azimuth;

Step 4: divide incidence angle processing to seismic data, comprise and protect width migration processing, obtain incidence angle part folded Add collection, the incident angle in incidence angle partial stack data is less than 30 degree;

Step 5: utilize different incidence angles stack road collection, in Jason software, implement the Sparse Pulse Inversion of well constraint, Ask for isotropic elastic impedance EI (i), i is incidence angle;

Step 6: calculate the ratio of calculation of elastic impedance in anisotropic media EI (i, φ) and isotropic elasticity impedance EI (i), use inverting Algorithm is asked for fracture spacing B^aniAnd fracture azimuth ф_S；

Step 7: prediction fracture reservoir development belt;

The dominance relation formula with fracture parameters and calculation of elastic impedance in anisotropic media EI (i, φ) described in step 2 is:

EI(i,φ)/EI(i)＝exp(2B^anicos²(φ-φ_s)sin²i)(1)。

2. the crack detection method based on azimuthal anisotropy elastic impedance according to claim 1, its Be characterised in that, the calculation of elastic impedance in anisotropic media Log-constrained curve in described step 2, is based on Ruger Reflectance factor approximate equation in the HTI medium proposing and the elastic impedance equation of Connolly, foundation Explicit functions between calculation of elastic impedance in anisotropic media and fracture parameters simulates; Wherein, velocity of wave in length and breadth Degree, density is obtained by log data, and fracture parameters is obtained by conventional AVOZ inversion result.

3. the crack detection method based on azimuthal anisotropy elastic impedance according to claim 1, It is characterized in that, the inversion algorithm relational expression described in step 6 is:

EI(i,φ)/EI(i)＝exp(2B^anicos²(φ-φ_s)sin²i)(1)

Ask for fracture spacing B^aniAnd fracture azimuth ф_STime according to following equation group:

$\left\{\begin{array}{c}\ln \left(EI\right(i,\mathrm{\φ})/EI\left(i\right))=C_1{\cos }^2{\mathrm{\φsin}}^{2}i+2C_2{\mathrm{sin\φcos\φsin}}^{2}i+C_3{\sin }^2{\mathrm{\φsin}}^{2}i\\ C_1=B^{ani}{\cos }^2{\mathrm{\φ}}_s\\ C_2=B^{ani}sin2{\mathrm{\φ}}_s\\ C_3=B^{ani}{\sin }^2{\mathrm{\φ}}_s\end{array}\right.---\left(2\right)$

4. the crack detection method based on azimuthal anisotropy elastic impedance according to claim 1, its Be characterised in that, described method is to combine to utilize isotropic elasticity impedance and calculation of elastic impedance in anisotropic media simultaneously Ask for fracture spacing B^aniAnd fracture azimuth ф_S。

5. the crack detection method based on azimuthal anisotropy elastic impedance according to claim 1, its Be characterised in that, the scope of application of described method in actual data application is as follows: the fracture spacing of surveying, Refer to the strength of anisotropy that effective fracture causes; Effective fracture referred to open and filling the crack of fluid, It is effective reservoir space of oil, gas, water; Strength of anisotropy is the coefficient result in many group cracks: when When within the scope of certain depth, effective fracture moves towards roughly the same, anisotropic degree is high; Otherwise, if necessarily Depth bounds in, the trend in crack presents different directions, the anisotropic character of seismic wave can be cut A little less than, even can demonstrate isotropic feature, cannot obtain by inverting the information of subterranean fracture.