Integral Forward Modeling Of Inhomogeneous Medium And Analysis Of Wavefield Characteristics

Wave field characteristics of non-homogeneous medium in seismic exploration has become a hot topic. Research on the scattered wave field has important significance on solving complex problems of non-homogeneous media. Based on the predecessors research results of the wave field in inhomogeneous media, discuss advantages and disadvantages of forward modeling in inhomogeneous media. We also give several forms of integral solutions of wave equation, discuss their conditions and restrictions. Given Huygens - Fresnel principle in the application of Kirchhoff integral. Green function method for solving wave equation, widely used as a more integral way wave equation, discussed in detail in the text, and verify the effect of its use, given the boundary surface and boundary conditions. Model through a few simple tests can be drawn, wave equation integral solutions forward modeling in the study of non-uniform characteristics of the wave field should have its unique advantages: it is able to take into account the different media in the role of the wave field position, the calculated wave field closer to the theoretical value.Research on the wave field in inhomogeneous media, this paper is accomplished through the actual data. In the paper, using the information of the Luzong arer, constructed several different geological model of magnetic iron ore. Through the analysis of the wave field characteristics in the forward modeling result, we obtained some conclusions about the scattering wave field in inhomogeneous media:First,non-homogeneous media play a important role in scattering wave field, to study non-uniform medium, scattering theory and scattering must have some benefit on understanding the wave field. Second, the distribution of underground metal mine in the non-homogeneous medium model is of a typical representative of non-homogeneous medium.We use Luzong metal mine to complete the forward modeling .Third, through the analysis of scattering wave field characteristics, draw some conclusions: the composition and the shape of the non-uniform media can influence wave field in inhomogeneous media, this is because the composition of non-uniform medium affect its physical properties, the velocity, density, etc., which determine the non-homogeneous medium with the surrounding medium wave impedance difference, then can affect the strength of the scatter wave field generated and distributed. The pattern is not uniform medium because it can affect the scattering of wave propagation path and the distribution of scattered waves, which affect the whole scattered wave field. However, these in this paper is a simple overview. Further study of specific correspondence should be searching.Fourth, the non-homogeneous media, construction also affect the scattered wave field of important factors. Massive ore body in isolation, steep dip, the fault of these geological structures such as dykes better response in the seismic record of the scattering profile can be reflected clearly. However, when these structures became more complex, and a variety of structures exist, the scattered wave field becomes very complex, non-uniform medium wave field in this record out on the difficult to distinguish.Through the study on random medium model and the wave field characteristics , we draw some conclusions on the complex heterogeneous medium and its wave field characteristics. Conclusions on the random medium are:First, elliptical Gaussian autocorrelation function describing the random medium with a single scale smooth features, and exponential and Von Karman-type autocorrelation function descripte the random media with multiple scales, self-similar characteristics, it seems more suitable to simulate the actual non-uniform medium;Second, the correlation length x and z descripte the scale in horizontal direction and depth direction of the random medium;Third, the standard deviation controls the disturbance speed range of the random medium .Conclusions on the scattering wave field characteristics of random media are:First,wave field in random medium is not a traditional reflection wave field, but a scattered wave field ,which need the scattering wave field theory to explain;Second, the size of the autocorrelation length of the random media medium impact the wave field, the bigger autocorrelation length, the more nearly uniform medium wave field. We also found that in the forward modeling, absorbing boundary conditions more conducive to random media, because the effects on the scattered wave field of the absorption boundary are smaller;Third, the source frequency in the random medium forward modeling play a very important role, to get the ideal random media scattering wave field, you must select the appropriate source frequency;Fourth, influence of random media in layered media is not only in the right random medium layer, but also the entire wave field, especially in the medium which under it .Overall, these findings for our study of complex heterogeneous medium and scattering wave field has important significance.In the process of research projects and papers completing also encountered many problems:First, observing system design is unreasonable, because non-uniform body shape affect the scattered wave field, observing system design directly influenced the acceptance of scattered wave field, the traditional system has been observed seismic wave field recorded in the explanation may be heterogeneous geologic body to explain the wrong phenomenon.Second,there is not a perfect mathod to modeling the non-homogeneous medium, all existing methods are mostly based on the homogeneous medium (or layered homogeneous medium).It's a limitation in study on non-homogeneous media,for the precision is not enough.Third, systematic research on the complex scattering field have not yet done, many studies are applicable for a particular situation, rather than the complex non-homogeneous medium .Use of the previous method is even possible misinterpretation.Fourth, no seismic simulation software for the non-uniform media. This greatly reduces the efficiency of seismic data acquisition and analysis.