Method for obtaining anisotropic seismic wave responses of coal seam
An anisotropic, seismic wave technology, applied in the field of seismic exploration, can solve the problems of error, weak anisotropy, and insignificant response characteristics of anisotropic coal seams
Active Publication Date: 2018-06-29
XIAN UNIV OF SCI & TECH
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Problems solved by technology
Correctly predicting whether the coal seam contains water or gas is very important for the safe mining of coal mines. Many scholars have conducted research on crack fillings in HTI-type coal seams. The identification methods mainly focus on the AVO response of seismic waves. Some experts also conduct research on crack fillings and seismic wave responses. , such as Bakulin (2000), but these studies have made a large degree of approximation when dealing with the anisotropic parameter formula, and this approximation is based on the assumption that the anisotropy is weak. Anisotropic HTI-type coal seams are not applicable, and large errors will occur, resulting in insignificant response characteristics of anisotropic coal seams
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[0029] According to the characteristics of the coal seam, an HTI type coal seam model is established, the thickness of the coal seam is 7m, the longitudinal and shear wave velocities of the coal seam are 1900m / s and 1090m / s respectively, and the coal seam density is 1.7g / cm 3 , the fracture density is 0.11, and the two cases of fractures containing saturated water and gas are discussed separately. When the fractures contain saturated water, the value of δ is -0.01499, and ε is 0. When the fractures contain gas, δ The value of ε is -0.31433, the value of ε is -0.29333, and the seismic wave response diagram is obtained, such as figure 1 , figure 2 All are shown in polar coordinates. figure 1 When the fracture contains gas, the obtained seismic wave response diagram, figure 2 is the seismic wave response diagram obtained when the fracture contains saturated water; where, figure 1 (a) in (a) is the relationship between P-wave phase velocity and phase angle obtained when the f...
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The invention discloses a method for obtaining anisotropic seismic wave responses of a coal seam. The method is used for obtaining the relationship between phase velocity and phase angle of longitudinal waves, the relationship between group velocity and group angle of the longitudinal waves, the relationship between phase velocity and phase angle of transverse waves and the relationship between group velocity and group angle of the transverse waves under different conditions that cracks contain gas or saturated water; the method is also used for obtaining different seismic wave responses underdifferent conditions that cracks in an HTI (transverse isotropy with a horizontal axis of symmetry) coal seam contain gas and saturated water; preparations can be made for subsequent anisotropic parameters and crack prediction.
Description
technical field [0001] The invention belongs to the technical field of seismic exploration and relates to a method for obtaining seismic wave responses of anisotropic coal seams. Background technique [0002] Fissures are usually well developed in the coal seam, and the existence of fissures in the medium will inevitably lead to anisotropy in the propagation of seismic waves. At the same time, because the thickness of the coal seam is relatively small compared with the seismic wavelet, and the shape of the fracture is complex, how to determine the subsurface through anisotropy analysis? The development of fissures is a difficult problem. [0003] There is a common crack in the coal seam, which is the approximate vertical crack, and the approximate vertical crack can usually be described by the HTI (Transverse isotropy with a horizontal axis of symmetry) medium, so the coal seam with vertical cracks can be approximately regarded as the HTI type coal seam . Correctly predict...
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IPC IPC(8): G01V1/30
CPCG01V1/306G01V2210/624
Inventor 李勤赵斌马随波
Owner XIAN UNIV OF SCI & TECH