The Characters Analysis About The Multiply Scatter Of Seismic Wave

The multiply scatter of the seismic wave plays an important role , which impresses the signal to noise ratio, during the geophysical signal processi-ng, it is caused by source and the characters of which is determined by the geometrical configuration of sub-scatter. The phenomena of multiply scat-tering can not be eliminated undoubtedly. The structure of our earth has been proved to be anisotropic extremely; in that case, the suppressing of the scattering effect is inevitable during the data processing. However, the plan is too hard to be executed, because of the less knowledge about the base scattering wave characters and the sub-earth, furthermore, the green the theories and technologies. Furthermore, there are a lot of problems will be formed during the conventional data processing, especially the NMO, stack, migration, which from the complicated structure-area. This paper is worked from these problems, and the reasons about them have been got by analyzing many velocity models which be calculated through finite differ- ence technology.At the beginning, we summing up the history of research and the resul-ts about the multiply scatter from others, and then an equation which can be used to describing the diffuse process on scatter-body be deduced, it is worked from the once scattering equation which approximated from the Kirchhoff integral. The gradual changing during the narrow sense scatter and the diffraction wave therefore be determined by the academic express-ing through a special break model. Furthermore, many models be calcula-teed through the high order finite-difference method, some rules and char-acters about the multiply scattering be summed by the numbers.The scattering process is intricate very much; the difference during re- sults from the different schemes will be tremendous, and it can be under-stood as a random processing sometimes even. It is unreadable but the base of our technology, a new arithmetic named as the adaptiveα? Tm mean filter which always been applied in the field of image processing been introduced for the first time for the filtering of scatter wave with Linear Move-out technology, and the idea be proved effective through forward modeling and the data be collected from a place in Jilin province, the wave be filtered completely and the scatter noise be suppressed effect-tively, at the same time, the signal be kept as best as we can. However, some shortages of the filter be showed by other data of metal mine from TONGLING region.We got some results from this paper, which will be listed by following:(1)The first Fresnel radio is very important, because it's the dividing value between the narrow scatter and diffraction. Any form of wave can be summarized as scatter, which is accord with the Hygen's Principle, for example, the scheme of reflection can be considered as scatter wave with powerful disciplinarian, and so on. However, the phenomena of diffraction will be weaken step by step, even disappear in the seismic recording when the transverse length of the scatter less than the first Fresnel radio, after th-at, the scatter wave is powerful which expressed as the form of resonance.(2)Generally speaking, both the energy and the frequency of the scatter will be weakening as the transverse length of the scatter larger. The char-acters be found that, when the scatter-body which is less than half of the wave length, the first order scatter will much stronger than multiply form, so does the frequency, however, the weaken action is obviously as the len-gth of model larger; the second orders scatter can be observed with the en-ergy and frequency however lower than the elementary value of the first order, but the highest; the third order scatter come to its top point when the parameter equal the wave length, all of them weaken as the length larger until the diffraction become the leading part and reflection later, in that ca- se, the characters of the multiply scatter are too hard to be analyzed, since its weak energy and the situation of both the diffraction and the scatter be mixed together but without an effective idea which can do a good job to divide them away.(3) The energy of the scatter is related to the angle of incidence. The power will be strongest when the transmitted direction of the incident wave is vertical to the scatter surface, at the same time, the reflected part hold the information of surface, a little of course. However, as the angle increasing, both the scatter and the reflection changing greatly with the former weaken gradually and the latter stronger, little information of the surface will be hold anymore. The scheme will be kept until the angle eq-ual to 90degree; no scatter phenomena can be recorded. More over, it is a fact which should be noticed that, both the reflection and the scatter will changed greatly than other parameter when the angle of incidence from 30 to 40, so, it should be the optimize value in exploration.(4) The conventional velocity analysis by reflecting method can be tru-sted when the geometric scale of scatter-body shorter than half wave leng-th or larger than the first Fresnel radio, however, the result will too disord-er to be utilized at all by other parameters. Finally, the technology such as NMO, stack, migration and so on can not show us a comfortable result du-ring the data processing especially in the place with complex structure su-ch as metal mine, because of the phenomena which expressed by either multiply velocity values or large variance range, if it's the latter case, the velocity can not be confirmed. The characters of the multiply scatter are too hard to be analyzed when the scale of scatter-body is larger than the first Fresnel radio, since its weak energy and the situation of both the diff-raction and the scatter be mixed together but without an effective idea wh-ich can do a good job to divide them away.(5)Both the character and energy of multiply scatter is determined by horizontal scale and the angle of incidence, litter effect will be done if the vertical scale of the scatter-body be changed, and the difference is unob-vious in frequency domain. Therefore, the problem of multiply scatter can be approximated by one direction, and the process will be simplified greatly.(6)The seismic data, which signal in it can be acknowledged, can be divided perfectly if the LMO correct and the adaptiveα-Tmmean filter be applied. The signal to noise ratio is improved, information about edge be kept, furthermore, the scatter and other kinds of noise be suppressed greatly. Even though, the application of the filter will be restricted when the signal in data is not obvious enough, wrong result and the Gibson aff-ection will be produced at the same time.It is a key technology in dealing with the problem of heterogeneous str-ucture exploration with scattering methods, and one of the most important challenges to be dealt with in the fields of metal mine exploration, or ener-gy resources exploration in the areas with complex lithologic characters. The results of this paper not only give out some reasons which can be used to explain the problems during the complex data processing by conventio-nal technology, but also beneficial to the academic research, at last, the arithmetic from other field can be applied in real data with an excellent effect.