CN102854527A - Fracture fluid identifying method based on longitudinal wave azimuthal AVO (Amplitude Variation with Offset) - Google Patents

Abstract

The invention relates to a fracture fluid identifying method based on longitudinal wave azimuthal AVO (Amplitude Variation with Offset). Fractures are reservoir spaces of oil gas and migration pathways of fluids, so that the fracture detection is significant on searching oil gas reservoirs. The identification of the fractures is the present research hotspot and difficult point and the identification of types of the fluids in the fractured reservoirs is doubly difficult. According to the method, the identification method of the types of the fluids in the fractures is further researched on the basis of anisotropy fracture inversion. Indicated by the forward modeling of a numerical model, the isotropy gradient and the anisotropy gradient in the world-famous Ruger equation have a certain capability of identifying the types of fracture fluids and particularly distinguishing dry fractures (filled with gas) and wet fractures (filled with oil and water). The method disclosed by the invention has the advantages of capability of being applied to actual data and identifying the types of the fluids in the fractures in areas relatively high in anisotropy degree.

Description

Fracture fluid recognition methods based on the compressional wave azimuthal AVO

Technical field

The invention belongs to petroleum exploration field, relate to the method for fracture fluid type identification in a kind of fracture reservoir comprehensive evaluation.

Background technology

The slit formation reservoir accounts for greatly 1/3rd of world's oil and gas reserves.Fracture development is all arranged in carbonatite, mud stone, sandstone, volcanics and the metamorphosed rock.The crack is the reservoir space of oil gas on the one hand, as the migration pathway of fluid, the hole reservoir space that disperses in the reservoir can be communicated with on the other hand.Therefore, the growth in prediction crack and distribution are significant for seeking oil and gas reservoir.The existence in crack makes reservoir have anisotropic character.The physical property (amplitude, speed, frequency etc.) that so-called anisotropy refers to seismic event changes with the variation of observed bearing.For the parallel fracture of homeotropic alignment, can be that HTI medium (Horizontal Transverse Isotropy namely has the Method in Transverse Isotropic Medium of horizontal symmetry axis) model is studied with its equivalence.Forefathers are to having carried out a large amount of theories and applied research (Malaysia and China's height, 2003 based on compressional wave azimuthal AVO feature (the amplitude anisotropic character of HTI medium) prediction fracture density and orientation; Ruger, 1998; Gray, 2008; Sun etc., 2011a; 2011b; Sun etc., 2012).The below provides fracture density and orientation inversion method based on the compressional wave azimuthal AVO commonly used: for little incident angle to middle angle, world-renowned Ruger longitudinal wave reflection coefficient equation is (Ruger, 1998):

Wherein

$P=\frac{1}{2}\frac{\mathrm{\ΔZ}}{\stackrel{\‾}{Z}}$

$\mathrm{Biso}=\frac{1}{2}[\frac{\mathrm{\Δ\α}}{\stackrel{\‾}{\mathrm{\α}}}-{\left(\frac{2\stackrel{\‾}{\mathrm{\β}}}{\stackrel{\‾}{\mathrm{\α}}}\right)}^2\frac{\mathrm{\ΔG}}{\stackrel{\‾}{G}}]$

$\mathrm{Bani}=\frac{1}{2}[\mathrm{\Δ}{\mathrm{\δ}}^V+2{\left(\frac{2\stackrel{\‾}{\mathrm{\β}}}{\stackrel{\‾}{\mathrm{\α}}}\right)}^2\mathrm{\Δ\γ}]$

In the formula: α, β are respectively velocity of longitudinal wave and shear wave velocity; Δ ε ^V, Δ δ ^V, Δ γ is the Thomsen parameter;

For gathering the position angle; Be fracture strike; I is incident angle; Wave impedance when Z is the compressional wave vertical incidence; G is the tangential modulus of shear wave.In (1) formula second (namely and sin ²The item that i multiplies each other) be the AVO gradient, gradient terms is divided into two parts: isotropy gradient Biso and anisotropy gradient Bani (this parameter can indicate the crack to cause anisotropic degree be fracture density).

The cosine term that comprises fracture azimuth is launched, can be converted into following form to formula (1):

Wherein

C ₁=P, C ₂=Biso+Bani/2,

The degree of covering of supposing common reflection point (CRP) point is N, C ₁, C ₂, C ₃, C ₄Be four unknown quantitys, then following formula can be reduced to:

AX＝B (3)

Wherein

Following formula is the overdetermination system of linear equations, and the crack inverse problem is exactly to find the solution the problem of unknown quantity X in the above-mentioned system of linear equations.Solve unknown vector X, can solve P, Biso, Bani reaches

P＝C ₁，Biso＝C ₂-Bani/2，

In order to carry out deeper oil-gas exploration, the fluid type in the crack identification is worth doing deep research.But than the prediction in fracture density and orientation, the identification of fracture inner fluid at present development is still immature.Bakulin etc. (2000) are in linear slide theoretical (Schoenberg, 1983) and Hudson theoretical (Hudson, 1981 of Schoenberg proposition; 1986) on the basis, the difference of Bani parameter in the situation of crack filling different fluid has been discussed, can be provided certain theoretical foundation for fracture fluid identification, that is:

(1) for dry and cracked seam (dried or filling gas):

$\mathrm{Bain}=\frac{4(-8{\mathrm{<figure-callout\; id="2"\; label="g"\; filenames="HSA00000748354800021.png"\; state="\{\{state\}\}">g</figure-callout>}}^2+12g-3)}{3(3-2g)(1-g)}\mathrm{\&zeta;}---\left(5\right)$

(2) for hygrochase seam (filling oil or water):

$\mathrm{Bain}=\frac{16g}{3-2g}\mathrm{\&zeta;}---\left(6\right)$

Wherein

Be transverse and longitudinal wave velocity ratio square; ζ is the crack volume density in the Hudson theory.

Shaw and Sen (2006) relation of compressional wave azimuthal AVO and crack compliance of having derived points out that forward compliance and the ratio of tangential compliance can be used as the indicator of fracture fluid type identification in addition.Yet the research that is identified in the present people of application in the real data for fracture fluid seldom.

Summary of the invention

The present invention proposes a kind of fracture fluid kind identification method based on the compressional wave azimuthal AVO, and the method can be used in the fracture fluid identification of real data.By method provided by the invention, can identify the fluid type of filling in the crack, particularly distinguish dry and cracked seam (dried or filling gas) and hygrochase seam (filling oil or water), describing for meticulousr fracture reservoir provides foundation.

The present invention realizes that the specific embodiments of above-mentioned purpose is as follows:

Step 1: (comprise and protect width of cloth migration processing) processed in seismic data minute orientation, extract minute orientation common reflection point (CRP) road collection;

Step 2: CRP road collection that will minute orientation carries out data and merges, and prepares for next step;

Step 3: carry out the crack inverting with algorithm of the present invention, calculate the crack isotropy gradient Biso on each time-sampling point and anisotropy gradient Bani (Biso and Bani two parameters are taken from the Ruger reflection coefficient equation that provides in the formula 1) on each CRP point;

Step 4: output isotropy gradient Biso and anisotropy gradient Bani data volume;

Step 5: isotropy gradient Biso and anisotropy gradient Bani are carried out intersection, in conjunction with the scope of just drilling information and fixed well data and sketch the contours of dry and cracked seam (dried or gassiness) and hygrochase seam (filling oil or water);

Step 6: obtain dry and cracked seam (dried or gassiness) and hygrochase seam (filling oil or water) scope in the plane by the intersection analysis.

Step 7: carry out the geological Significance analysis.

Ultimate principle based on compressional wave azimuthal AVO crack identification fluid type provided by the present invention is as follows:

The method continues the fluid type in the crack identification on the inversion method basis, crack based on the compressional wave azimuthal AVO commonly used, Anisotropic inversion result in the formula (4) to the Bani parameter get on the occasion of, for the result of applicating road inverting, in fracture fluid identification, the Bani parameter of dry and cracked seam and hygrochase seam is all done the processing that takes absolute value.Utilize formula (5) and formula (6), behind fixing crack volume density ζ, can study the Bani absolute value with the rule of the variation of background rock transverse and longitudinal wave velocity ratio.Research can get, when background rock transverse and longitudinal wave velocity than less than 0.7 the time, the anisotropy degree Bani during filling gas is higher.Take of the present invention be among the embodiment study area Xinjiang block carbonate reservoir as example, its transverse and longitudinal wave velocity is than about 0.5, be generally less than 0.7, therefore when the factors such as identical when the background rock in this zone, fracture strike and dense degree were constant, the Bani of gas-bearing fracture was large during than oil-containing and water.

Next the relative variation relation of isotropy gradient Biso parameter in the Ruger formula is discussed in the medium in the filling different fluid situation.It is as follows to derive:

$\mathrm{Biso}=\frac{1}{2}(\frac{\mathrm{\&Delta;\&alpha;}}{\stackrel{\&OverBar;}{\mathrm{\&alpha;}}}-{\left(\frac{2\stackrel{\&OverBar;}{\mathrm{\&beta;}}}{\stackrel{\&OverBar;}{\mathrm{\&alpha;}}}\right)}^2\frac{\mathrm{\&Delta;G}}{\stackrel{\&OverBar;}{G}})=\frac{{\mathrm{\&alpha;}}_2^2-{\mathrm{\&alpha;}}_1^2-8{\stackrel{\&OverBar;}{\mathrm{\&beta;}}}^2\frac{\mathrm{\&Delta;G}}{\stackrel{\&OverBar;}{G}}}{{({\mathrm{\&alpha;}}_2+{\mathrm{\&alpha;}}_1)}^2}---\left(7\right)$

For fixing model, the speed alpha 1 of top dielectric is also constant, and when the different fluid of filling, shear wave velocity can not change, namely

Can not change.Unique variation be that the crack is containing the velocity of longitudinal wave α of medium in the different fluid situation ₂, therefore can be by finding the solution Biso to α ₂Derivative analyze the Changing Pattern of Biso.Can get through differentiate:

$\frac{\&PartialD;\mathrm{Biso}}{{\&PartialD;\mathrm{\&alpha;}}_2}=\frac{2({\mathrm{\&alpha;}}_1{\mathrm{\&alpha;}}_2+{\mathrm{\&alpha;}}_1^2+8{\mathrm{\&beta;}}^2\frac{\mathrm{\&Delta;G}}{\stackrel{\&OverBar;}{G}})}{{({\mathrm{\&alpha;}}_1+{\mathrm{\&alpha;}}_2)}^3}>0---\left(8\right)$

Therefore Biso is with α ₂Increase and increase.For the same background rock, velocity of longitudinal wave α during filling gas ₂Low than filling water or when oil, so Biso is lower.Can be understood as like this, in the constant situation of the factors such as background rock speed, crack character, Biso is lower during than oil-containing and water when the gassiness of crack, and Bani is higher than the Bani value in oil-containing and the moisture situation during simultaneously in conjunction with gassiness previously discussed, can distinguish G﹠O water.

The scope of application of fracture detection is as follows among the present invention: the well (organizing the crack) that presents different directions for free from flaw and fracture strike more, a little less than the anisotropic degree, the unpredictable fluid type that goes out in the well of the fluid prediction method on the anisotropic analysis basis of being based upon; Only present the well in a certain predominant direction (single group crack) for fracture strike, when its anisotropic degree is stronger, could predict fluid type wherein.

Description of drawings

Fig. 1 is slit formation reservoir forward model synoptic diagram.

Fig. 2 is full of different fluid minute orientation Dao Ji.

Fig. 3 (a) is Bani and the Biso X plot that does not add noise, is full of the collection inverting of fluid road;

Fig. 3 (b) is Bani and the Biso X plot that adds 50% noise, is full of the collection inverting of fluid road.

Fig. 4 adds Bani and the Biso X plot that 50% noise, difference contain the collection inverting of fluid saturation road.

Fig. 5 is based on the fracture fluid recognition methods process flow diagram of compressional wave azimuthal AVO.

Fig. 6 is Xinjiang block Bani and Biso X plot.

Fig. 7 is Xinjiang this block C well inverted parameters intersection.

Fig. 8 is that this block hawk mountain group prediction fracture fluid of Xinjiang distributes.

Fig. 9 is this block hawk mountain, Xinjiang group top structure figure.

Embodiment

Below in conjunction with embodiment and the description of drawings specific embodiment of the invention.

Fig. 1～Fig. 4 illustrates the validity of this fracture fluid recognition methods with the numerical model forward simulation.Carry out forward simulation based on Xinjiang block slit formation reservoir special geologic condition in the embodiment of the invention, used model as shown in Figure 1, model is altogether two-layer, the upper strata is limestone matrix, lower floor is fracture medium.Shown in the medium parameter subordinate list 1 of background Rock Matrix parameter and filling gas, oil and water.

Table 1 crack stuff parameter

Stuff and character thereof	Background media	Gas	Oil	Water
					Velocity of longitudinal wave (m/s)	6000	350	1300	1647
Shear wave velocity (m/s)	3100	10	10	10
					Density (kg/m 3)	2670	270	880	1100

The fluid-filling saturation degree can be calculated according to the Wyllie time-average equation speed and the density parameter of equivalent fluid not simultaneously in the crack.Wyllie time-average equation following (Wyllie, 1958):

$\frac{1}{v}=\frac{\mathrm{\&phi;}}{v_1}+\frac{1-\mathrm{\&phi;}}{v_2}---\left(9\right)$

In the formula: v is the speed of equivalent fluid, v ₁Be the speed of the first inclusion, v ₂Be the speed of the second inclusion, φ is (volume) number percent that the first inclusion accounts for fluid.According to subordinate list 1 and above formula, calculate velocity of longitudinal wave and density in the different fluid component situation, shown in subordinate list 2 (annotate: o represents oil, and g represents gas, and w represents water).

The physical parameter of table 2 crack inner fluid

	Fluid components	Velocity of longitudinal wave (m/s)	Density (kg/m 3)
				1	o∶g＝10∶0	1297.0	880.0
2	o∶g＝8∶2	842.0	758.0
				3	o∶g＝6∶4	623.0	636.0
4	o∶g＝4∶6	494.0	514.0
				5	o∶g＝2∶8	410.0	392.0
6	o∶g＝0∶10	350.0	270.0
				7	g∶w＝8∶2	415.0	436.0
8	g∶w＝6∶4	511.0	602.0
				9	g∶w＝4∶6	664.0	768.0
10	g∶w＝2∶8	946.0	934.0
				11	g∶w＝0∶10	1648.0	1100.0
12	w∶o＝8∶2	1563.0	1056.0
				13	w∶o＝6∶4	1487.0	1012.0
14	w∶o＝4∶6	1418.0	968.0
				15	w∶o＝2∶8	1355.0	924.0

Fig. 2 is the theogram minute orientation Dao Ji that is full of in the different fluid situation, its objective is to observe the difference that different fluid is concentrated in the road.Its specific practice is as follows: on the used numerical model basis of Fig. 1, and the calculation of parameter Hudson elastic parameter (Hudson, 1981 that are full of gas, oil and water that provide according to subordinate list 1; 1986), utilize the Hudson elastic parameter to calculate Thomsen parameter (Ruger and Tsvankin, 1997), carry it into the Ruger formula and just drilling and obtain theogram minute orientation Dao Ji.Convenient for showing inversion result, extract respectively the constant offset distance, the position angle is 0 °～180 ° road collection, analyzes orientation amplitude variations rule.As can be seen from Figure 2, the crack be full of behind the gas the orientation amplitude variations than be full of oil and water after the orientation amplitude variations large, explanation is in the constant situation of background rock p-and s-wave velocity, density and crack character, and is large when being full of anisotropic degree ratio behind the gas and being full of oil and water.

Fig. 3 is fracture fluid intersection analysis result of the present invention, with the scope of explanation different fluid data point.Utilize the above-mentioned theogram road collection that obtains of just drilling, carry out inverting, obtain Biso and Bani parameter.Carry out respectively inverting with the road collection after not containing noise and adding 50% noise and obtain Bani and Biso parameter X plot, shown in Fig. 3 (a), (b).Light grey ellipse sketches the contours the scope of giving vent to anger among the figure, and the Dark grey ellipse sketches the contours fuel-displaced and scope water, and the oval representative of black does not contain the zone that the isotropy rock in crack and gas that the noise disturbance causes and profit are difficult to distinguish.Can find out that from Fig. 3 (a) parameter point of gas and profit can significantly be distinguished when not adding noise; Shown in Fig. 3 (b), add 50% noise after, the scope of black ellipse (zone that the gas that the noise disturbance causes and profit are difficult to distinguish) enlarges, but gas and profit can be distinguished in this model on the whole.

Fig. 4 carries out Biso and the Bani parameter X plot that inverting obtains with the different road collection that contain fluid saturation.Calculation of parameter Hudson elastic parameter (Hudson, 1981 in the different fluid saturation degree situation that provides according to subordinate list 2; 1986), utilize the Hudson elastic parameter to calculate Thomsen parameter (Ruger and Tsvankin, 1997), carry it into the Ruger formula and just drilling and obtain theogram minute orientation Dao Ji, carry out inverting and obtain Biso and Bani parameter X plot.Light grey oval indication gas saturation is greater than 60% zone, and Dark grey oval indication oil-containing or water is greater than 60% zone, and the oval indication of black does not contain the zone that the isotropy rock in crack and gas that noise causes and profit are difficult to distinguish.As can be seen from the figure, global regularity is that main gassiness parameter point drops on the below, and main oil-containing water parameter point drops on the top.

Fig. 1～Fig. 4 explanation utilizes Bani and Biso parameter intersection analytical approach to stitch (oil-containing water) to dry and cracked seam (dried or gassiness) and hygrochase and distinguishes.

Fig. 5 is that fracture fluid is identified in process flow diagram in the actual data application among the present invention:

Step 1: (comprise and protect width of cloth migration processing) processed in seismic data minute orientation, extract minute orientation common reflection point (CRP) road collection;

Step 2: CRP road collection that will minute orientation carries out data and merges, and prepares for next step;

Step 3: carry out the crack inverting with algorithm of the present invention, calculate the crack isotropy gradient Biso on each time-sampling point and anisotropy gradient Bani on each CRP point;

Step 4: output isotropy gradient Biso and anisotropy gradient Bani data volume;

Step 5: isotropy gradient Biso and anisotropy gradient Bani are carried out intersection, in conjunction with the scope of just drilling information and fixed well data and sketch the contours of dry and cracked seam (dried or gassiness) and hygrochase seam (filling oil or water);

Step 6: obtain dry and cracked seam (dried or gassiness) and hygrochase seam (filling oil or water) scope in the plane by the intersection analysis.

Step 7: carry out the geological Significance analysis.

Below on the block real data of Xinjiang, be applied as the practical application effect that example specifies the method with the method.

Fig. 6 is Xinjiang this block Bani and Biso X plot.According to aboveground Given information, delimit the scope of G﹠O water, respectively shown in light color and dark wire frame among the figure.When sketching the contours gas and profit scope, mainly consider following 2 points:

(1) for avoiding the impact of noise, chooses the larger zone of Bani value.

(2) crack contain the factor affecting such as fluid saturation to the differentiation of G﹠O water, be outstanding gassiness and the reservoir that contains profit, only sketch the contours gassiness or the higher zone of profit saturation degree.

Fig. 7 is Xinjiang this block C well inverted parameters intersection and the contrast of this well condition of production.On the formation testing result, this well day produce oil 10.37 sides, aerogenesis 54505 sides.After analyzing by intersection, the position of this well aerogenesis and produce oil water shown in the black region of Fig. 7 right side, epimere aerogenesis, hypomere produce oil and water.Because the density ratio of gas oil and water are little, general gas is positioned at oil and side waterborne when distributing in reservoir, and this well fluids predicts the outcome and has certain rationality.

Fig. 8 is that this block hawk mountain group fracture fluid of Xinjiang predicts the outcome, and wherein background color represents the fracture density of inverting.To the well of Image Logging Data is arranged, trend and the number of high seam guide in the group depth range of statistics hawk mountain, and show the FMI data linear fracture density (Number of Fractures on the unit length) of the bright statistics of rose diagram sidenote at the crack of correspondence polar plot with the form of rose diagram.The fracture density size of inverting distributes closely related with number and the fracture strike in crack.When in the certain depth scope, when fracture strike is consistent (types of fractures is defined as single group), linear fracture density is larger, and seismic event is propagated anisotropic degree stronger (such as A well, B well, C well, D well, E well) in fracture medium; If fracture strike different (types of fractures is defined as many groups) a little less than the anisotropic degree of seismic event, is used anisotropy and is carried out fracture detection DeGrain (F well, I well, G well, H well).The identical situation that the statistics fluid predicts the outcome.Many group crack wells and fissureless well anisotropic degrees weak (F well, I well, G well, H well), the unpredictable fluid type that goes out in the well of the fluid prediction method on the anisotropic analysis basis of being based upon.Only for the well in single group crack, when its anisotropic degree is stronger, could predict fluid type wherein.In the well (A well, B well, C well, D well, E well) in single group crack, the A well does not dope the fluid distribution, and except this well, other are all identical with aboveground oil test data, the identical rate 80% of well fluids prediction in single group crack.By finding that with hawk mountain group top structure figure (Fig. 9) contrast the fluid of prediction mainly concentrates on local structure high-order bit, this distribution has certain rationality.On the whole, fracture fluid predicts the outcome rationally, proves that the method has certain actual application value.

List of references

Malaysia and China's high .P ripple Data Inversion crack method and example. geophysical prospecting for oil, 2003,38 (5): 517-521.

Gray D.Fracture Detection Using 3D Seismic Azimuthal AVO.CSEG Recorder，2008，38-49.

Sun S Z，Xiao X，Wang Z et al.P-wave fracture prediction algorithm using prestack data with limited azimuthal distribution.2011a，73 ^rd EAGE annual meeting，Expanded abstract.

Sun S Z，Wang Z，Yang H et al.P-wave fracture prediction algorithm using pre-stack data with limited azimuth distribution：A case study in the TZ45 area，Tarim Basin，China.Petroleum Science，2011b，8(4)：422-432.

Sun S Z，Xiao X，Chen L et al.P-wave fracture prediction algorithm using data with limited azimuthal distribution.

The Leading Edge，2012，31(2)：198-205.

Ruger A.Variation of P-wave reflectivity with offset and azimuth in anisotropic media.Geophysics，1998，63(3)：935-947.

Wyllie M R J，Gregory A，Gardner G.An experimental investigation of factors affecting elastic wave velocities in porous media.Geophysics，1958.

Bakulin A，Grechka V，Tsvankin I.Estimation of fracture parameters from reflection seismic data-Part I：HTI model due to a single fracture set.Geophysics，2000，65(6)：1788-1802.

Schoenberg M A，1983，Reflection of elastic waves from periodically stratified media with interfacial slip：Geophysical prospecting，31：265-292.

Shaw R K，Sen M K.Use of AVOA data to estimate fluid indicator in a vertically fractured medium.Geophysics，2006，71(3)：C15-C24.

Hudson J A.Wave speeds and attenuation of elastic waves in material containing cracks.Geophysical Journal of the Royal Astronomical Society，1981，64：133-150.

Hudson J A.A higher order approximation to the wave propagation constants for a cracked solid.Geophysical Journal of the Royal Astronomical Society，1986，87：265-274.

Ruger A，Tsvankin I.Using AVO for fracture detection：Analytic basis and practical solutions.The Leading Edge，1997，1429-1434。

Claims (3)

1. an effective fracture fluid kind identification method based on the compressional wave azimuthal AVO is characterized in that, comprises the steps:

Step 1: (comprise and protect width of cloth migration processing) processed in seismic data minute orientation, extract minute orientation common reflection point (CRP) road collection;

Step 2: CRP road collection that will minute orientation carries out data and merges, and prepares for next step;

Step 3: carry out the crack inverting with algorithm of the present invention, calculate the crack isotropy gradient Biso on each time-sampling point and anisotropy gradient Bani (Biso and Bani two parameters are taken from world-renowned Ruger reflection coefficient equation) on each CRP point;

Step 4: output isotropy gradient Biso and anisotropy gradient Bani data volume;

Step 5: isotropy gradient Biso and anisotropy gradient Bani are carried out intersection, in conjunction with the scope of just drilling information and fixed well data and sketch the contours of dry and cracked seam (dried or gassiness) and hygrochase seam (filling oil or water);

Step 6: obtain dry and cracked seam (dried or gassiness) and hygrochase seam (filling oil or water) scope in the plane by the intersection analysis.

Step 7: carry out the geological Significance analysis.

2. the fracture fluid recognition methods based on the compressional wave azimuthal AVO according to claim 1, it is characterized in that, the information of just drilling in the described step 5, to obtain by numerical model: from world-renowned Ruger reflection coefficient formula, obtain crack isotropy gradient Biso and anisotropy gradient Bani in the formula by common reflection point (CRP) theogram road collection inverting, the two is carried out the intersection analysis, in conjunction with the known fracture fluid information of numerical model, obtain the scope of dry and cracked seam (dried or gassiness) and hygrochase seam (filling oil or water).

3. the fracture fluid recognition methods based on the compressional wave azimuthal AVO according to claim 1, it is characterized in that, the scope of application of fracture fluid recognition methods in actual data application is as follows: free from flaw and fracture strike present the well (organizing the crack) of different directions more, a little less than the anisotropic degree, the unpredictable fluid type that goes out in the well of the fluid prediction method on the anisotropic analysis basis of being based upon; Only present the well in a certain predominant direction (single group crack) for fracture strike, when its anisotropic degree is stronger, could predict fluid type wherein.

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