A Study On The Primary Energy Of Scattered Wave Imaging

Due to the enhancement of the degree of complexity and sophistication aboutthe solution of geological problems, the conventional reflection seismic explorationtechnology can’t be well applied in the exploration, include the piedmont fault zone、the basin margin fracture zone and the concealed metal ore, and it is difficult to obtainaccurate imaging effect; Therefore, the scattering wave seismic methods is proposedwith the complex exploration of the tectonic or lithology complex oil and gasexploration and the buried metal mine. It is a exploration method that is based on theseismic wave scattering theory, and uses more generalized scattering wave to describecomplex seismic wave field from variety of scale non-uniform geological. Thescattered wave imaging is a migration method that dependent on the seismicscattering wave theory, and belongs to pre-stack time migration, which provides aunique research idea for seismic imaging and velocity analysis.On the basis of previous work, I particularly understand the seismic scatteredwave field theory and find out the essential difference of between the scattered wavefield and the reflected wave field, have a clear about the kinematic characteristics ofthe scattered wave, that the traveltime-offset surface form scattered wave is a Choepspyramid; according to the principle of equivalent offset, forming the commonscattering point (CSP) gathers is the committed step of scattered wave imaging,which’s essence is the process of re-choose seismic trace information in accordancewith the size of the equivalent offset. this gather have greater offset coverage andhigher signal to noise ratio, and improve the accuracy of velocity analysis, which isthe foundation for the improvement in imaging.The basic purpose of this paper is that confirm the possibility of using the mainenergy information of scattered wave to improve the scattering imaging, based on thetheory of the main energy of seismic scattered wave, which is the value of the paper.The scatterers and the background media meet different scale relations, which resultin the different types of scattered mechanisms; When the compressional wave isincident on the geological body, I systematically analysis of the pattern of forward scattering and backscattering; in the premise of some assumptions and ignore somefactors, I find the discipline between the direction of scattered wave main energy andinclination of the geological, then do the weighted imaging according to theprinciples that the weight coefficient of the main energy direction is one, the weightedcoefficient of others direction gradually reduce in accordance with scatteringattenuation pattern,which highlight the affection of main energy to imaging, andachieve the calculation of main energy weight coefficient and forming the commonscattering gathers by programming. Processing the model data and filed data, what’sresult have a comparison with the effect of the previous unweighted imaging whichimprove the signal to noise ratio, and effectively suppress the multiple reflections andspatial aliasing, meanwhile the scattered wave events become more hyperbolic,highlighted the main energy information, and weaken the non-primary energyinformation. the stacked section enhance the continuity of the subsurface geologicbody, and improve the imaging effect. This method can effectively deal with lowsignal to noise ratio and irregular seismic data and can improve the imaging ofsmall-scale geological body, especially used in shallow data. Finally I summarize theadvantages and disadvantages of this method, and give my expectation of it.