Research On Excitation Technology Based On Near-surface Model

Aiming at the problem of low signal-to-noise ratio of seismic exploration data under complex surface conditions,we study the propagation characteristics of seismic waves in near-surface by wave equation forward modeling technique,and explore seismic excitation technology in complex area through seismic source sombining theory,which strive to make new progress in seismic data collection in complex areas.As the main source of seismic exploration on land,the explosive source is the key factor to determine the quality of field seismic data.Due to the complexity of the near-surface structure,the dramatic changes in lithology,the existence of abnormal superficial structures and other factors,a single source of excitation energy generated by the radiation can not be uniform when collecte seismic data in a complex area,but by the impact of near-surface factors have a serious attenuation,resulting in a significant decline in the energy to the target layer,the signal to noise ratio of seismic data also decreased.Therefore,the conventional single well excitation has been unable to meet the needs of complex areas of high precision seismic exploration.In order to improve the signal-to-noise ratio of seismic data in complex areas,this paper has done the following research work on the basis of predecessors' research:1)Based on the geologic data of the field,we establish the near surface model of the complex area and study the energy distribution law of the source region under the near surface model by the forward modeling of the acoustic wave equation,and then we divide the source wave field;2)we analysis the influence of near-surface factors such as inclination,thickness,lithology and abnormal structure on the excitation energy of the source quantitatily;3)This paper makes a detailed study on the main factors that stimulate the combination of phased array source;4)Combining with conventional combined source excitation technology and phased array source excitation technology,this paper propose an optimization algorithm of excitation parameters based on near-surface model,and aiming at the different complex near surface model,the optimal design of the excitation depth,the excitation dose,the element interval,the number of the source and the delay time are optimized and the optimal combination excitation parameter.The directional propagation of the excitation energy of the source is realized theoretically,the energy of the source and the signal-to-noise ratio of the local data is improved.And through the actual field of information to verify,which achieved good application results.