The Acoustic Numerical Simulation For Anisotropic Media

Seismic numerical simulation is to study the propagation law of the seismic wave in the underground media and compute the records of every receiver point, when assuming the given physical parameters and the medium structure. The property of anisotropy is widely existed in the actual formation,In modern times, for the sake of searching the concealed oil and gas area more accurate, it is very necessary, taking the anisotropy of the underground media into consideration, to make the complex structure of underground clear under the circumstance of the increasing difficulty in the resource exploration. It cost more time and calculated amount in the simulation process because of the varied elastic anisotropic parameters when using conduct elastic simulation on the anisotropic media. Actually, the deficiency of computation will become more obvious with more parameters need to be solved on the seismic subsequent processing procedure.In order to simulate the propagation characteristic of the seismic wave on anisotropic medium with more efficiency, we do the research on the method of acoustic anisotropic approximation. The theory of acoustic anisotropic approximation is setting the velocity of S-wave into zero in elastic modeling, which greatly simplifies the elastic wave equation with the elimination of these calculated parameters. Accordingly, we can get the same simulation effect compared with the elastic simulation on anisotropic media in practical application on account of reserving the P-wave section, which can reflect the formation information on acoustic anisotropic wave equation. Therefore, under the condition of ensuring the simulation accuracy, it can increase the computational efficiency with reducing the calculated amount in a great deal.The acoustic approximation is an effective method in the process of the numerical simulation and the migration imaging in the anisotropic media. Adopting the acoustic approximation is preferable approach in simplifying the procedure of the elastic wave modeling in the TI (Transverse Isotropy) media. Applying the acoustic anisotropic simulation will be a more advisable choice in the practical use due to the great amount of calculation and time-consuming computation of the traditional elastic anisotropic simulation in the following intervention and migration imaging process, which will have a better applicability on the modeling of the complicated formation.hi this paper we start from the parameters relationship of anisotropy to derive an anisotropic wave equation with second order in time and forth order in space through acoustic approximation of VTI media. Then, we adopt absorption attenuation boundary to handle the reflection boundary and solve the dispersion by using high order difference operator in space. We can compare the similarities and differences among acoustic isotropic, elastic anisotropic and acoustic anisotropic simulation by numerical examples on single, horizontal layered and vertical layered media. Then, acoustic wave equation for TTI media, suitable for any inclination, can be obtained from the formula derivation and the introduction of rotation matrix, which is better applicable to the Tilted strata model in the actually use. Finally, the effectiveness and the feasibility of the acoustic approximation can be tested by the numerical example of the comparison of the simulation results and the synthetic seismogram between the acoustic and the elastic anisotropic media.