Research On Directional Excitation Method For Seismic Exploration Of Complex Structures

The underground structure and the near-surface condition are complicated,resulting in weak effective signals and serious noise.Therefore,the signal-to-noise ratio is low in complex areas,the imaging quality is poor,and the construction explaining is difficult.Due to the complexity of the wave field,data processing is difficult,and the effective wave damage is serious when denoising,so the signal-to-noise ratio should be improved from the source of data collected.A large number of field tests have shown that combined excitation is an effective means to improve the quality of data collected in complex areas.The reason is that the combination can increase the energy of the downstream and gather the energy in a narrow range and suppressing the noise.Conventional combinations consider how to design parameters to improve the focus of the combination,and the directionality of the combination is often neglected.Considering the directionality of seismic waves traveling underground,designing a combination scheme with specific directivity is more advantageous to project energy to the area of weak reflection.Based on the research of predecessors and scholars,this paper mainly studies the following contents:1)Combining the actual data in the field,through the numerical simulation of acoustic wave equation,the seismic wave energy propagation law in complex tectonic regions is studied by numerical simulation of acoustic wave equations,and the source excitation wave field region is divided;2)The main factors affecting the phase-controlled source combination effect are studied in detail;3)the source is excited at the underground target position,and the upward illumination technology of the shot is used to study the propagation law of the seismic wave energy at the position,so as to determine the favorable excitation region.The main beam direction of the directional combined source is calculated by the Poynting vector;4)Combining the directional combined source excitation technique,the objective function for optimizing the combined parameters is designed,and the combined parameters are optimized.The seismic wave is excited by the directional combination,the projection of the energy of the target position is improved,the signal-to-noise ratio of the seismic data is improved,and the method is applied to the actual geological model,and good results are obtained,and the feasibility is verified.