Research On Protection And Extension Methods For Seismic Low Frequencies

Due to the limitation of the source and receiver in the process of acquisition,and the diffusion and attenuation of wave field while seismic wave travels in the ground,seismic data lack of low-frequency components in field acquisition.During the suppression of surface wave can also lead to lack more low-frequency components.However,the lack of low frequency information will effect the resolution,the quality of the deep structure imaging,the precision and stability of inversion and hydrocarbon detectio,so the low frequencies of the seismic data is very important.This article in view of the low frequency characteristics,and carry on the exploration study on protection and extension methods for seismic low frequencies.Firstly,the seismic wavelet,single-channel seismic records,the typical geological model and multiple tectonic inversion are discussed,and seismic frequency information missing features are summarized.Put forward in the acquisition and processing,pay attention to the protection of the low-frequency information,extension low frequencies of seismic that missing low frequency information,rich low frequency information,provide the seismic data include effective low-frequency information for inversion and interpretation,so as to improve the precision of reservoir prediction.Secondly,we analysis the influence of low frequency information in key seismic processing,and the damage of low frequency information in suppressing surface wave.For conventional surface wave suppression methods damage effective low-frequency information,and study the adaptive surface wave suppression method based on radial trace transform and SVD.Its principle is introduced,and its algorithm is decomposed.Finally through the validation of theoretical model and application of actual seismic data,proved that this method is good in the suppression of surface wave,most of the low frequency information of data does not produce any loss at the same time.Its technical advantages compared with other methods appear more prominent.And aiming at the effects of stack to spectrum of data,this paper puts forward the method of low frequency stability method based on CIP gathers,achieved a certain effect in the application on real data.Thirdly,for lack of the low frequency information in seismic data after seismic acquisition and processing,we introduce two method including low frequency expansion method based on the autoregressive(AR)model spectrum extrapolation and low frequency expansion method based on compressed sensing theory.Through the theoretical model and real data examples show that the method is also able to effectively expand the low frequency information.Finally,the above mentioned methods are encapsulated,developed the corresponding low frequency seismic data protection and develop software.Through theoretical model test the feasibility of the software,and finally apply it to the actual seismic data.