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Reverse Time Migration Of VSP Seismic Data

Posted on:2016-08-01Degree:MasterType:Thesis
Country:ChinaCandidate:X B GuoFull Text:PDF
GTID:2180330461981339Subject:Earth Exploration and Information Technology
Abstract/Summary:PDF Full Text Request
Conventional VSP imaging methods only using upgoing wave and take it as one reflection wave, downgoing wave has not been fully taken advantage of. However,downgoing wave is important for the imaging of structure that have high and steep dip Angle.Meanwhile, upgoing wave also limit the scope of imaging due to limited lighting. By contrast,VSP reverse time migration can imaging different kinds of wave(one reflection wave,multiple wave, prismatic wave, et al.) in theory and no dip angle limits. Therefore, the aboundant wavefield information of VSP data is very suitable for reverse time migration and will make up for the inadequacy of traditional methods.This paper first briefly introduces some modes of VSP observation, illustrates the characteristics of VSP data and clarify the important value of VSP data for complex structural exploration. Secondly, we study different seismic wavefield numerical simulation approaches and give the brief description of different methods, like conventional grid, variable grid,frequency domain modeling and two-step explicit marching. Each of them has its advantages that can improve accuracy or efficiency. In terms of storage, we adopt a kind of storage strategy that can greatly reduce the storage and not affect the accuracy. In terms of denoising,we compare the effect of different low frequency noise suppression methods. In computing,we realize the GPU accelerating computation of algorithm, and test three-dimensional model by using more GPU cards in the process of parallel computation, the computational efficiency has significantly improved. Then we analyze the various factors that affect the effect of the reverse-time migration to achieve better result. Through the complicated model test, we verify the actual effect of the algorithm. And take the algorithm integrated in the Qt platform to form portable VSP migration interface. Finally, we study the full waveform inversion algorithm to provide guarantee for the reverse-time migration velocity modeling.
Keywords/Search Tags:VSP data, reverse time migration, GPU accelerating computation, storage
PDF Full Text Request
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