Study On Seismic Scattering Wave Imagination

Along with urgently awaits to be solved the complication degree of geological question and to solve the question fine degree further enhancement, the malpractice and the question that the multifold reflected wave exploration technical has exposed are getting more and more. Although it can enhance the signal-to-noise ratio of seismic data well, in the complex structure situation, particularly the fault zone of mountain front, the crushed zone of basin edge, exploration question of magmatic intrusion as well as the survey question of nonuniformity prominent region in near surface, it is difficulty to obtain the precise imaging result. The reason is that the theory of the tradition reflected exploration technical has defined it is impossible to overstep the ability that withdraws geological feature accurately and geological information completely. Moreover, the traditional methods only apply the sole type seismic wave field (for example reflected wave, surface wave, refracted wave and so on) to carry on imaging, the imaging effect and the ability of geology information extracting is limited certainly, particularly the effect is worse in geological situation complex region. Actually the seismic wave which carries the geological information is very rich. And the sole type seismic wave (for example reflected wave) only manifests one part or one hand of the geological attributes information, has defined the ability of extracting geology information well. This article has developed the seismic scattered wave imaging method and technical research systematically, namely applying the seismic scattering wave field which is more widespread significance for seismic wave field to carry on imaging.In the existing seismic scattering wave theory foundation, in view of the characteristic of seismic scattering wave propagating, this paper has established the point scattering seismic geological model, based on this, consummated the seismic scattering wave geometry kinematics, summarized the seismic scattering wave time-distance curve rule, and has carried on analyzing and contrasting the time-distance curve characteristic and rule for scattering wave with traditional reflected wave, at the same time, proposed the concept of apparent reflected wave.With the wave field numerical simulation of the typical geological model, this paper analyzed the seismic scattering wave propagation characteristic thoroughly. The research has indicated that the seismic reflected wave in the traditional significance is not reflected wave in fact, but is the final outcome which the seismic scattering wave interfered mutually. The seismic scattering wave is the basic feature which the isolated geological body appeared. As a result of the interference effect, the continuous medium already blurred the partial seismic scattering wave basic propagation attribute, particularly in the elastic contact surface situation with horizontal and continues. In addition with the influence of background noise, the scattering wave nature has not been discovered easily. But, when contact surface not neat and nonuniform prominent, the propagation nature and the rule of the seismic scattering wave are highlighted, especially unusual geological phenomenon, such as thin out point, fault and so on. There will be the extraordinary wave with traditional significance in seismic record (for example diffracted wave, fault section wave and so on), and the seismic scattering wave propagation rule and the nature has been manifested at this time.Through analyzing scattering wave time-distance rule, this paper obtained that the relation of the scattering wave time-distance curve characteristic only relating with the upgoing wave, and the rule following hyperbolic curve characteristic. But the downgoing wave only relates with the length of the travel time. As for the converted wave, the propagation velocities of downgoing and upgoing wave are each other isolated, certainly the time-distance curve rule also following hyperbolic curve characteristic. This provides one new mentality and theory to support for seismic converted wave processing and information acquisition.Based on the propagation rule of seismic scattering wave, this paper studied on seismic scattering wave imaging velocity analysis method and technical, and analyzed the similarities and differences thoroughly as well as superiority-inferiority of the technical with the tradition velocity analysis technical and the technical of basing on equivalent off-setting seismic scattering wave velocity analysis. When data acquiring, under the premise of tradition fold number fixed, the scattering velocity analysis technical not only made the focusing ability of effective scattering wave energy to be stronger, but also could enhance the signal-to-noise ratio effectively, simultaneously used on the information with the traditional extraordinary wave of diffracted wave and fault section wave etc to carry on velocity analysis. Because the technical used on the seismic information which fully all gathered, simultaneous the times of stacking number is able to enhance greatly. Therefore, compared with the tradition velocity analysis technical, the technical could gain the imaging velocity precisely, especially to the seismic data of constructed complex region and low signal-to-noise ratio area, which could avoid the malpractice of the extraordinary wave false energy group affected in the traditional technical effectively, simultaneously may reduce influence of multiple wave.In the foundation of seismic scattering wave velocity analysis technical, this paper studied on the seismic scattering wave imaging method and technical in time domain. With the point scattering geological model, the technical does not need gathers collection, but bases on the scattering wave time-distance curve hyperbolic rule, adopts single point optimization imaging. Comparing with the traditional horizontal stacking imaging technical under the premise of tradition fold number fixed, the stacking number of the imaging technical is enhance greatly. Moreover, because gained the precise imaging velocity, simultaneously used on the information with the traditional extraordinary wave of diffracted wave and fault section wave etc carry on imaging, therefore, the technical not only enhanced the signal-to-noise ratio effectively, but also could increase the imaging precision greatly; At the same time, because the imaging position and the region may act according to the actual situation to define, so long as the region of the gathering data covered may carry on the imaging. Therefore compared with the traditional imaging technical, the imaging technical can extend imaging region. And the gained geological information is richer.In the foundation of the velocity analysis and imaging technical, compiled the related software, and established several sets of typical geological models (horizontal level model, fault model, thin interbed model, angle plane of unconformity model, hollow model) to carry on imaging processing and analysis with the effect, this paper has made a good progress.In view of the actual data, this paper has established standard seismic scattering wave processing flow, analyzed this technical congenital superiority from the processing craft, and carry on contrasting and analyzing with traditional standard imaging processing flow (post-stack imaging, pre-stack imaging, based on equivalent offset seismic scattering wave imaging and so on), which obtained the precise of the gained velocity becoming immediate influence to the imaging quality. The gained velocity precision of the technical in this article is high, moreover processing flow direct-viewing perspicuity and simple.Based on this, urgently awaits the actual geological question which from the reality is solved to embark, in view of the near surface engineering and environment survey, the urban active fault survey, the coal field and oil gas seismic exploration and the development question, this paper has processed several sets of actual data (including single component, multi-components), and carry on contrasting and analyzing with the result of the tradition velocity analysis and post-stack migration technical, has obtained a very rich understanding.