Characteristics Analysis Of Seismic Data In Beach Shallow Sea Area And Research Of Noise Suppression

The surface structure of beach shallow sea area is complex, so the noise in the seismic data which collected at this area is very diverse and distributes widely. Due to the big differences in sources and detectors, the dynamic attributions of the seismic data collected in the same exploratory area are different. At first, We analyzed the differences in energy, frequency, phase and the wavelet of the seismic data of this area,guiding the follow-up matching works. Also, for building a foundation for noise suppression, we had analyzed the generation, propagation, and the characteristic of the noise of the seismic data collected at beach shallow sea area :â‘ the characteristics of multiple: the velocity of multiple is lower than effective signal's at the same time in the seismic data. Internal multiples appear periodically.â‘¡the characteristics of surface wave: the frequency and apparent velocity of surface wave is low; surface wave is a type of coherent noise; the energy of surface wave is very strong, but it will attenuate along with the passage of time and the increase of offset.â‘¢the characteristics of 50Hz industrial interference: its value of frequency is 50 Hz, not changed; its energy is strong; it distributes widely and irregularly, It exists in the stable receiver which nearby the high-tension wire.Aim at the characteristics of interference wave of seismic data in beach and shallow sea, we has provided a series of specific methods and techniques which could overcome the impact of these disturbances and instruct the following matching works.â‘ Multiple suppression technique of seismic data in beach shallow sea area: Conventional multiple suppressing method of seismic data is mainly the parabolic Radon transform. Affected by many factors, this kind of conventional method of suppressing is not ideal, and will destroy the relative relations of amplitude. Through the processing of a model gather and actual data, proved that the "two-step" linear Radon Transform in this paper can suppress multiples effectively, but has the minor damage to the significant wave. According to the conventional processing technique can not retain AVO phenomenon when it removes multiples, the Deletion Fitting method was developed by LiQingzhong. The processing of a model gather and actual data confirms this method can remove multiples and random noise efficiently but retain AVO phenomenon. We can choose the suitable multiple suppression method according to the need in beach shallow sea area seismic data processing.â‘¡Surface wave suppression technique of seismic data in beach shallow sea area: The staple surface wave attenuation methods is F_K domain filtering and F_X Coherent Noise Suppression based on apparent velocity and frequency, the ZAP method based on amplitude difference between signal and noise. For separating the signal and the surface wave, the first two methods transform the seismic data to F_K domain or F_X domain. The principle of ZAP is decompose the amplitude of seismic data to four different domains, finding out the abnormal value of the amplitude and remove it in each four domains. Through the contrast effect on the three methods for suppressing surface wave, concluded that after suppressing surface wave using Fxcns, compared with two other methods of surface wave suppression, the seismic data show a wider frequency band, a stronger energy and the higher signal-noise ratio, this method is an ideal surface wave suppression method in the area.â‘¢50Hz industrial disturbance suppression technique of seismic data in beach shallow sea area:In accordance with the characteristic of the broad distribution in actual seismic data processing and hard to elimination of the 50Hz industrial disturbance, a method for suppressing effectively 50Hz industry disturbance-separation in geophone domain is developed. This method is based on the characteristic that the energy of signal is weak but the energy of 50Hz industrial disturbance is very strong in deep seismic data. For increasing the signal-noise ratio for further data processing, we predict the 50Hz industrial disturbance using deep seismic data, remove it from seismic data. The processing results of actual data have proved that the technology of suppressing the 50Hz industrial interference in geophone domain is more efficient and better, and improved the signal-to-noise ratio of seismic data greatly; according to the actual seismic data, this technology can suppress the 50Hz industrial disturbance in the control window for maximize to protect the effective signal.We have processed the beach shallow sea area seismic data applying the noise suppression techniques introduced in this paper, it improved the signal-to-noise ratio of seismic data greatly. This working builds a foundation for follow-up high precision migration and interpretation...