CN111551990A - Method and system for calculating seismic wave reflection coefficient of HTI (HTI) coal seam - Google Patents

Method and system for calculating seismic wave reflection coefficient of HTI (HTI) coal seam Download PDF

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CN111551990A
CN111551990A CN202010265242.9A CN202010265242A CN111551990A CN 111551990 A CN111551990 A CN 111551990A CN 202010265242 A CN202010265242 A CN 202010265242A CN 111551990 A CN111551990 A CN 111551990A
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CN111551990B (en
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李勤
王玮
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Xian University of Science and Technology
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Abstract

The invention discloses a method and a system for calculating seismic wave reflection coefficients of an HTI coal seam, and particularly calculates the seismic wave reflection coefficients based on a formula (1). The method can ensure the influence weight of the fracture parameters on the reflection coefficient and reserve the high-order term of a calculation formula, thereby improving the calculation precision of the seismic wave reflection coefficient and having obvious resolution on the fracture type and the fracture density of the coal bed.

Description

Method and system for calculating seismic wave reflection coefficient of HTI (HTI) coal seam
Technical Field
The invention belongs to the technical field of geological exploration, and particularly relates to a method and a system for calculating seismic wave reflection coefficients of an HTI coal bed.
Background
The horizontal cracks of the coal bed are nearly closed under the action of top plate compaction, multiple vertical cracks develop, the coal bed is equivalent to an HTI medium, the influence of crack density on the reflection coefficient of the coal bed is researched, a theoretical basis can be provided for crack prediction, and the method has important significance for coal field exploration.
The AVO (amplitude returns) theory is originated from Zeoppritz equation, and means that the amplitude of reflected wave changes along with the offset, the concrete form of the crack is identified in the coal seam, the AVO technology is an effective method, along with the development of the AVO theory, R ü ger utilizes Thomsen anisotropic parameters and crack parameters to derive R ü ger reflection coefficient formula, Ivan
Figure BDA0002441024640000011
The weak anisotropic medium reflection coefficient formula based on the wa (peak anistropy) parameter is also derived. The two formulas have advantages, but are mainly applicable to oil-gas seismic exploration, the main difference between a coal bed and an oil layer is that the wave impedance difference between the coal bed and surrounding rock is large, the wave impedance difference of the oil layer is small, an angle approximate formula commonly adopted in an AVO approximate formula is not established any more, and the approximate formula and an accurate solution error are large. Therefore, a formula with higher order term retention of anisotropy parameters, capability of describing the large offset situation more accurately and higher precision needs to be derived.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a method and a system for calculating the seismic wave reflection coefficient of an HTI type coal seam, and solve the problem that the existing AVO technology is not sufficient in accuracy when used for coal seam exploration.
In order to solve the technical problems, the invention adopts the following technical scheme:
a method for calculating seismic wave reflection coefficient of HTI coal seam includes calculating seismic wave reflection coefficient by the following formula
Figure BDA0002441024640000021
Figure BDA0002441024640000022
wherein ,
Figure BDA0002441024640000023
Figure BDA0002441024640000024
Figure BDA0002441024640000025
Figure BDA0002441024640000026
Figure BDA0002441024640000027
Figure BDA0002441024640000028
Figure BDA0002441024640000029
in the above formula, θ represents the incident angle of the PP wave;
Figure BDA0002441024640000031
represents the incident angle of the PP wave;
Figure BDA0002441024640000032
representing the velocity mean of longitudinal waves of overlying mudstone and underlying coal seam,
Figure BDA0002441024640000033
VP1representing the longitudinal wave velocity, V, of the overburdenP2Representing the longitudinal wave velocity of the underlying coal seam;
ΔVPrepresenting the difference, Δ V, in longitudinal wave velocity between overlying mudstone and underlying coal seamP＝VP1-VP2；
Figure BDA0002441024640000034
Representing the mean of the transverse wave velocities of the overlying mudstone and the underlying coal seam,
Figure BDA0002441024640000035
VS1representing the transverse wave velocity, V, of overlying mudstoneS2Representing the shear wave velocity of the underlying coal seam;
Figure BDA0002441024640000036
represents the mean of the vertical longitudinal wave impedances of the overlying mudstone and the underlying coal seam,
Figure BDA0002441024640000037
ρ1representing the density, ρ, of overlying mudstone2Represents the density of the underlying coal seam;
Δ Z represents the difference in vertical longitudinal wave impedance between overlying mudstone and underlying coal seam, where Δ Z is ρ1VP1-ρ2VP2；
Figure BDA0002441024640000038
Means of shear modulus of shear waves of overlying mudstones and underlying coal seams,
Figure BDA0002441024640000039
Δ G represents the difference in shear modulus of the shear waves of the overlying mudstone and the underlying coal seam;
Figure BDA00024410246400000310
lambda and mu represent Lame constants of a lower-lying coal bed without cracks;
(v)representing the degree of longitudinal wave anisotropy of the underlying coal bed;
(v)the degree of anisotropy change of longitudinal waves of the underlying coal seam between the transverse direction and the vertical direction is represented;
e represents the fracture density of the coal bed;
U11and U33Is two constants determined by the fracture state of the coal seam, and for dry fractures,
Figure BDA00024410246400000311
for saturated water fracture, U11＝0，
Figure BDA00024410246400000312
xWhich is indicative of a first parameter of the image,zwhich is indicative of a second parameter of the first,xdenotes a third parameter, γxDenotes a fourth parameter, γyA fifth parameter is indicated.
Specifically, the longitudinal wave velocity VP1、VP2Velocity V of sum transverse waveS1、VS2Is calculated by the following formula to obtain,
Figure BDA0002441024640000041
Figure BDA0002441024640000042
Figure BDA0002441024640000043
the invention also discloses a calculation system for the seismic wave reflection coefficient of the HTI type coal bed, which comprises
A parameter acquisition module for acquiring the longitudinal wave velocity V of the PP wave in the upper shale layerP1Longitudinal wave velocity V of PP wave in lower coal seamP2Transverse wave velocity V of PP wave in upper layer mudstoneS1Transverse wave velocity V of PP wave in lower coal seamS2Density rho of upper layer mud rock stratum1Density rho of the lower coal seam2Fracture density e of the lower coal seam and Lame constants lambda and mu of the background coal seam;
a calculation module for calculating the reflection coefficient of the seismic wave according to the following formula
Figure BDA0002441024640000044
Figure BDA0002441024640000045
Wherein the content of the first and second substances,
Figure BDA0002441024640000046
Figure BDA0002441024640000047
Figure BDA0002441024640000048
Figure BDA0002441024640000051
Figure BDA0002441024640000052
Figure BDA0002441024640000053
Figure BDA0002441024640000054
in the above formula, θ represents the incident angle of the PP wave;
Figure BDA0002441024640000055
represents the incident angle of the PP wave;
Figure BDA0002441024640000056
representing the velocity mean of longitudinal waves of overlying mudstone and underlying coal seam,
Figure BDA0002441024640000057
VP1representing the longitudinal wave velocity, V, of the overburdenP2Representing the longitudinal wave velocity of the underlying coal seam;
ΔVPrepresenting the difference, Δ V, in longitudinal wave velocity between overlying mudstone and underlying coal seamP＝VP1-VP2；
Figure BDA0002441024640000058
Representing the mean of the transverse wave velocities of the overlying mudstone and the underlying coal seam,
Figure BDA0002441024640000059
VS1representing the transverse wave velocity, V, of overlying mudstoneS2Representing the shear wave velocity of the underlying coal seam;
Figure BDA00024410246400000510
represents the mean of the vertical longitudinal wave impedances of the overlying mudstone and the underlying coal seam,
Figure BDA00024410246400000511
ρ1representing the density, ρ, of overlying mudstone2Represents the density of the underlying coal seam;
Δ Z represents the difference in vertical longitudinal wave impedance between overlying mudstone and underlying coal seam, where Δ Z is ρ1VP1-ρ2VP2；
Figure BDA00024410246400000512
Means of shear modulus of shear waves of overlying mudstones and underlying coal seams,
Figure BDA00024410246400000513
Δ G represents the difference in shear modulus of the shear waves of the overlying mudstone and the underlying coal seam;
Figure BDA00024410246400000514
lambda and mu represent Lame constants of a lower-lying coal bed without cracks;
(v)representing the degree of longitudinal wave anisotropy of the underlying coal bed;
(v)the degree of anisotropy change of longitudinal waves of the underlying coal seam between the transverse direction and the vertical direction is represented;
e represents the fracture density of the coal bed;
U11and U33Is two constants determined by the fracture state of the coal seam, and for dry fractures,
Figure BDA0002441024640000061
for saturated water fracture, U11＝0，
Figure BDA0002441024640000062
xWhich is indicative of a first parameter of the image,zwhich is indicative of a second parameter of the first,xdenotes a third parameter, γxDenotes a fourth parameter, γyA fifth parameter is indicated.
Specifically, in the parameter obtaining module, the longitudinal wave velocity VP1、VP2Velocity V of sum transverse waveS1、VS2Is calculated by the following formula to obtain,
Figure BDA0002441024640000063
Figure BDA0002441024640000064
Figure BDA0002441024640000065
compared with the prior art, the invention has the beneficial effects that:
the method can ensure the influence weight of the fracture parameters on the reflection coefficient and reserve the high-order term of a calculation formula, thereby improving the calculation precision of the seismic wave reflection coefficient and having obvious resolution on the fracture type and the fracture density of the coal bed.
Drawings
FIG. 1 is an azimuth angle
Figure BDA0002441024640000067
R ü ger formula and Ivan at 90 DEG
Figure BDA0002441024640000066
And calculating a result by using a formula.
FIG. 2 is an azimuth angle
Figure BDA0002441024640000068
The R ü ger formula is the calculation result of the formula of the method of the invention when the temperature is 0 ℃.
FIG. 3 is a spatial surface diagram of a reflection coefficient calculated by a saturated water fracture coal seam model by using the formula of the invention.
FIG. 4 is a spatial surface plot of the reflection coefficient calculated by the model of the coal seam containing the dry fractures using the formula of the present invention.
The details of the present invention are explained in further detail below with reference to the drawings and the detailed description.
Detailed Description
The invention relates to a method for calculating seismic wave reflection coefficient of HTI type coal bed, which calculates the seismic wave reflection coefficient by the following formula
Figure BDA0002441024640000071
Figure BDA0002441024640000072
Wherein the content of the first and second substances,
Figure BDA0002441024640000073
Figure BDA0002441024640000074
Figure BDA0002441024640000075
Figure BDA0002441024640000076
Figure BDA0002441024640000081
Figure BDA0002441024640000082
Figure BDA0002441024640000083
in the above formula, θ represents the incident angle of the PP wave;
Figure BDA0002441024640000084
represents the incident angle of the PP wave;
Figure BDA0002441024640000085
representing the velocity mean of longitudinal waves of overlying mudstone and underlying coal seam,
Figure BDA0002441024640000086
VP1representing the longitudinal wave velocity, V, of the overburdenP2Representing the longitudinal wave velocity of the underlying coal seam;
ΔVPrepresenting the difference, Δ V, in longitudinal wave velocity between overlying mudstone and underlying coal seamP＝VP1-VP2；
Figure BDA0002441024640000087
Representing the mean of the transverse wave velocities of the overlying mudstone and the underlying coal seam,
Figure BDA0002441024640000088
VS1representing the transverse wave velocity, V, of overlying mudstoneS2Representing the shear wave velocity of the underlying coal seam;
Figure BDA0002441024640000089
represents the mean of the vertical longitudinal wave impedances of the overlying mudstone and the underlying coal seam,
Figure BDA00024410246400000810
ρ1representing the density, ρ, of overlying mudstone2Represents the density of the underlying coal seam;
Δ Z represents overlying mudstone and underburdenDifference of vertical longitudinal wave impedance of coal seam, Δ Z ═ ρ1VP1-ρ2VP2；
Figure BDA00024410246400000811
Means of shear modulus of shear waves of overlying mudstones and underlying coal seams,
Figure BDA00024410246400000812
Δ G represents the difference in shear modulus of the shear waves of the overlying mudstone and the underlying coal seam;
Figure BDA00024410246400000813
lambda and mu represent Lame constants of a lower-lying coal bed without cracks;
(v)one of Thomsen anisotropy parameters of the underlying coal seam represents the degree of longitudinal wave anisotropy of the underlying coal seam;
(v)the second Thomsen anisotropic parameter of the underlying coal bed represents the degree of anisotropy change of the longitudinal wave between the transverse direction and the vertical direction;
e represents the fracture density of the coal bed;
U11and U33Is two constants determined by the fracture state of the coal seam, and for dry fractures,
Figure BDA0002441024640000091
for saturated water fracture, U11＝0，
Figure BDA0002441024640000092
xWhich is indicative of a first parameter of the image,zwhich is indicative of a second parameter of the first,xdenotes a third parameter, γxDenotes a fourth parameter, γyRepresents the fifth parameter, the five parameters are WA parameters and have no dimension, and the calculation of the five parameters shows the relationship between Thomsen anisotropy parameters and WA parameters.
The WA parameter is controlled by the Thomsen parameter, so that the fracture density of the Thomsen parameter is keptInfluence the weight, and reserve Ivan
Figure BDA0002441024640000094
The high-order term of the formula is suitable for calculating the reflection coefficient in the coal bed with small fracture density.
The invention also discloses a computing system of the seismic wave reflection coefficient of the HTI type coal seam, which comprises a parameter acquisition module and a computing module, wherein:
the parameter acquisition module is used for acquiring the longitudinal wave velocity V of the PP wave in the upper shale layerP1Longitudinal wave velocity V of PP wave in lower coal seamP2Transverse wave velocity V of PP wave in upper layer mudstoneS1Transverse wave velocity V of PP wave in lower coal seamS2Density rho of upper layer mud rock stratum1Density rho of the lower coal seam2The fracture density e of the lower coal seam and the Lame constants lambda and mu of the coal seam without fractures;
the calculation module is used for calculating the seismic wave reflection coefficient through the formulas (1) to (8)
Figure BDA0002441024640000095
In the parameter acquisition module, the longitudinal wave velocity VP1、VP2Velocity V of sum transverse waveS1、VS2Can be obtained by a detection method; the following formula can also be specifically adopted for calculation:
Figure BDA0002441024640000093
Figure BDA0002441024640000101
Figure BDA0002441024640000102
the invention preferably uses the formula for calculation, and can save the detection expense.
The following provides a simulation experiment of the invention, and the effect of the method of the invention is verified.
Simulation experiment:
according to the characteristics of the coal bed, a two-layer model is established, wherein the upper layer is isotropic mudstone, the upper layer does not contain cracks, and the lower layer is an HTI type crack-containing coal bed with different crack densities and different crack fillers. According to the existing measured data, the longitudinal wave velocity V of the roof mudstone is measured during modelingP1Is 3170m/s, transverse wave velocity VS1At 1585m/s, density ρ1Is 2.36kg/m3. For a saturated water crack type coal seam, when the crack density e is 0.05-0.25, the longitudinal wave velocity V of the coal seamP2Are 2468m/s and transverse wave velocity VS2Are all 1471m/s, density rho2Is 1.33kg/m3(ii) a The Lame constant lambda of the coal bed is 2.34, and the mu is 2.875; for a dry fractured coal bed, when the fracture density e is 0.05, the longitudinal wave velocity V of the coal bedP22454m/s and transverse wave velocity VS2Is 1471m/s, density rho2Is 1.33kg/m3(ii) a When the fracture density e is 0.15, the longitudinal wave velocity V of the coal bedP22420m/s, transverse wave velocity VS2Is 1471m/s, density rho2Is 1.33kg/m3(ii) a When the fracture density e is 0.25, the longitudinal wave velocity V of the coal bedP22406m/s, transverse wave velocity VS2Is 1471m/s, density rho2Is 1.33kg/m3(ii) a The Lame constant lambda of the coal seam is 2.34, and the mu is 2.875. The incident angle theta is 0-60 DEG, the azimuth angle
Figure BDA0002441024640000105
Is 0 to 180 degrees.
The existing R ü ger formula and Ivan are used in the simulation experiment
Figure BDA0002441024640000103
The formula is compared with the reflection coefficient calculated by the calculation formula in the method of the present invention, as shown in FIG. 1, the existing R ü ger formula and the existing Ivan
Figure BDA0002441024640000104
The reflection coefficient contrast of the formula in an isotropic medium can be seen as R ü ger formula, Ivan
Figure BDA0002441024640000111
The formulas are completely overlapped in an isotropic medium, and the anisotropic terms only influencing the calculation accuracy are described.
FIG. 2 is a comparison of the reflection coefficient calculated by the R ü ger formula when the fracture density e is 0.05 and the approximate solution and the accurate solution of the reflection coefficient calculated by the formula of the present invention in the HTI coal seam model, and it can be found that the formula of the present invention is closer to the accurate solution, and the calculation accuracy is improved.
In order to study the calculation accuracy of the reflection coefficient of the HTI coal seam in the method of the invention at different fracture densities, the formula in the method of the invention is programmed and tried on an MATLAB software platform to obtain a reflection coefficient space curved surface diagram of an HTI coal seam model at different fracture densities, as shown in FIGS. 3 and 4. It can be seen from the figure that: the reflection coefficient of the model is symmetrical about the azimuth 90 degrees within the range of the azimuth angle of 0-180 degrees, and the maximum value appears at the azimuth 90 degrees, so that the symmetry axis of the crack in the coal seam can be inferred to be at the azimuth of 0 degrees, and the effectiveness of the reflection coefficient calculation formula is verified; when the azimuth angle is far away from the 90-degree azimuth, the reflection coefficient has obvious descending trend along with the increase of the incident angle when the azimuth angle is close to 0 degrees or 180 degrees, the anisotropic characteristic is enhanced, and the anisotropy of the coal bed model is verified to be mainly caused by the development azimuth and the development density of the fracture. In fig. 3, the absolute value of the reflection coefficient of the saturated water fracture model increases with the increase of the fracture density, and the larger the fracture density is, the larger the fluctuation range of the reflection coefficient curved surface is. In fig. 4, the decreasing amplitude of the reflection coefficient space curved surface of the dry fracture model is increased when the incident angle is larger, and the minimum value is far smaller than that of the saturated water fracture model. Comparing fig. 3 and fig. 4, it can be seen that the amplitude of the reflection coefficient space curved surface of the saturated water fracture model is smaller than that of the dry fracture model. The results of fig. 3 and 4 are combined to show that the reflection coefficient calculation formula of the method has obvious resolution on the coal seam fracture type and fracture density.
It should be noted that the present invention is not limited to the following embodiments, and all equivalent changes based on the technical solutions of the present application fall into the protection scope of the present invention.
The respective specific technical features described in the above-described embodiments may be combined in any suitable manner without contradiction as long as they do not depart from the gist of the present invention, and should also be regarded as being disclosed in the present invention.

Claims (4)

1. A method for calculating seismic wave reflection coefficient of HTI type coal bed is characterized in that the seismic wave reflection coefficient is calculated by the following formula
Figure FDA0002441024630000011
Figure FDA0002441024630000012
Wherein the content of the first and second substances,
Figure FDA0002441024630000013
Figure FDA0002441024630000014
Figure FDA0002441024630000015
Figure FDA0002441024630000016
Figure FDA0002441024630000017
Figure FDA0002441024630000018
Figure FDA0002441024630000019
in the above formula, θ represents the incident angle of the PP wave;
Figure FDA0002441024630000021
represents the incident angle of the PP wave;
Figure FDA0002441024630000022
representing the velocity mean of longitudinal waves of overlying mudstone and underlying coal seam,
Figure FDA0002441024630000023
VP1representing the longitudinal wave velocity, V, of the overburdenP2Representing the longitudinal wave velocity of the underlying coal seam;
ΔVPrepresenting the difference, Δ V, in longitudinal wave velocity between overlying mudstone and underlying coal seamP＝VP1-VP2；
Figure FDA0002441024630000024
Representing the mean of the transverse wave velocities of the overlying mudstone and the underlying coal seam,
Figure FDA0002441024630000025
VS1representing the transverse wave velocity, V, of overlying mudstoneS2Representing the shear wave velocity of the underlying coal seam;
Figure FDA0002441024630000026
represents the mean of the vertical longitudinal wave impedances of the overlying mudstone and the underlying coal seam,
Figure FDA0002441024630000027
ρ1representing the density, ρ, of overlying mudstone2Represents the density of the underlying coal seam;
Δ Z represents the difference in vertical longitudinal wave impedance between overlying mudstone and underlying coal seam, where Δ Z is ρ1VP1-ρ2VP2；
Figure FDA0002441024630000028
Means of shear modulus of shear waves of overlying mudstones and underlying coal seams,
Figure FDA0002441024630000029
Δ G represents the difference in shear modulus of the shear waves of the overlying mudstone and the underlying coal seam;
Figure FDA00024410246300000210
lambda and mu represent Lame constants of a lower-lying coal bed without cracks;
(v)representing the degree of longitudinal wave anisotropy of the underlying coal bed;
(v)the degree of anisotropy change of longitudinal waves of the underlying coal seam between the transverse direction and the vertical direction is represented;
e represents the fracture density of the coal bed;
U11and U33Is two constants determined by the fracture state of the coal seam, and for dry fractures,
Figure FDA00024410246300000211
for saturated water fracture, U11＝0，
Figure FDA00024410246300000212
xWhich is indicative of a first parameter of the image,zwhich is indicative of a second parameter of the first,xdenotes a third parameter, γxDenotes a fourth parameter, γyA fifth parameter is indicated.
2. The method for calculating the seismic reflection coefficient of an HTI coal seam according to claim 1, wherein the velocity V of the longitudinal wavesP1、VP2Velocity V of sum transverse waveS1、VS2Is calculated by the following formula to obtain,
Figure FDA0002441024630000031
Figure FDA0002441024630000032
Figure FDA0002441024630000033
3. a computing system for seismic wave reflection coefficient of HTI type coal bed is characterized by comprising
A parameter acquisition module for acquiring the longitudinal wave velocity V of the PP wave in the upper shale layerP1Longitudinal wave velocity V of PP wave in lower coal seamP2Transverse wave velocity V of PP wave in upper layer mudstoneS1Transverse wave velocity V of PP wave in lower coal seamS2Density rho of upper layer mud rock stratum1Density rho of the lower coal seam2Fracture density e of the lower coal seam and Lame constants lambda and mu of the background coal seam;
a calculation module for calculating the reflection coefficient of the seismic wave according to the following formula
Figure FDA0002441024630000034
Figure FDA0002441024630000035
Wherein the content of the first and second substances,
Figure FDA0002441024630000036
Figure FDA0002441024630000037
Figure FDA0002441024630000038
Figure FDA0002441024630000041
Figure FDA0002441024630000042
Figure FDA0002441024630000043
Figure FDA0002441024630000044
in the above formula, θ represents the incident angle of the PP wave;
Figure FDA0002441024630000045
represents the incident angle of the PP wave;
Figure FDA0002441024630000046
representing the velocity mean of longitudinal waves of overlying mudstone and underlying coal seam,
Figure FDA0002441024630000047
VP1representing the longitudinal wave velocity, V, of the overburdenP2Representing the longitudinal wave velocity of the underlying coal seam;
ΔVPrepresenting the difference, Δ V, in longitudinal wave velocity between overlying mudstone and underlying coal seamP＝VP1-VP2；
Figure FDA0002441024630000048
Representing the mean of the transverse wave velocities of the overlying mudstone and the underlying coal seam,
Figure FDA0002441024630000049
VS1transverse wave representing overlying mudstoneSpeed, VS2Representing the shear wave velocity of the underlying coal seam;
Figure FDA00024410246300000410
represents the mean of the vertical longitudinal wave impedances of the overlying mudstone and the underlying coal seam,
Figure FDA00024410246300000411
ρ1representing the density, ρ, of overlying mudstone2Represents the density of the underlying coal seam;
Δ Z represents the difference in vertical longitudinal wave impedance between overlying mudstone and underlying coal seam, where Δ Z is ρ1VP1-ρ2VP2；
Figure FDA00024410246300000412
Means of shear modulus of shear waves of overlying mudstones and underlying coal seams,
Figure FDA00024410246300000413
Δ G represents the difference in shear modulus of the shear waves of the overlying mudstone and the underlying coal seam;
Figure FDA00024410246300000414
lambda and mu represent Lame constants of a lower-lying coal bed without cracks;
(v)representing the degree of longitudinal wave anisotropy of the underlying coal bed;
(v)the degree of anisotropy change of longitudinal waves of the underlying coal seam between the transverse direction and the vertical direction is represented;
e represents the fracture density of the coal bed;
U11and U33Is two constants determined by the fracture state of the coal seam, and for dry fractures,
Figure FDA0002441024630000051
for saturated water fracture, U11＝0，
Figure FDA0002441024630000052
xWhich is indicative of a first parameter of the image,zwhich is indicative of a second parameter of the first,xdenotes a third parameter, γxDenotes a fourth parameter, γyA fifth parameter is indicated.
4. The HTI-type coal seam seismic reflection coefficient calculation system as defined in claim 3, wherein in said parameter acquisition module, the velocity V of longitudinal wavesP1、VP2Velocity V of sum transverse waveS1、VS2Is calculated by the following formula to obtain,
Figure FDA0002441024630000053
Figure FDA0002441024630000054
Figure FDA0002441024630000055
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Citations (10)

* Cited by examiner, † Cited by third party
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