Wave Field Response Characteristics And Application Of Shallow Reflection Seismic Exploration

The exploration of fault structure is an important part of urban geological survey.By using the method of reflection seismic exploration,the location of the fault structure can be explored and its characteristics are evaluated.Due to the limitation of the method,there are many influencing factors in shallow seismic exploration,and its exploration resolution for geological anomalies such as fault structure is relatively low.Therefore,it is of great practical application value to carry out the research of this method.Based on theoretical analysis,numerical simulation and exploratory experiments,the response characteristics of the reflected waves in shallow environment are studied,and the applicability of the method is discussed.Based on the finite difference method of two-dimensional viscoelastic wave equation and the basic theory of reflection wave,the physical property difference,seismic geophysical characteristics and shallow seismic exploration method of shallow strata are analyzed and studied.The construction simulation of various elements of the shallow geological conditions of fault fault theory two-dimensional geological model,using Ricker wavelet for vibroseis and perfectly matched layer absorbing boundary conditions,the numerical simulation of finite difference for high precision two-dimensional viscoelastic wave equation for fault activity,buried depth,dip angle and the width of the fault zone fault elements.Through the comparison of single shot record,time section and instantaneous attribute profile simulation results,starting from the wave amplitude,frequency,phase,reveal the wave field response characteristics,analyze the influencing factors and characteristics.The test results show that the seismic reflection and diffraction wave instantaneous phase section of the fault zone is more sensitive to the detection effect is better than the time section;the instantaneous amplitude and instantaneous frequency section profile can be effective in the fault depth,dip angle and width of fracture zone for qualitative and semi quantitative detection.In the actual engineering detection test,the instantaneous attribute section can be combined to verify the identification and tracking of the fault structure in the time section.Quanshan fault of Shungeng Mountaint detection experiments further show that,in the stack section on the basis of the multi attributes section of underground fault structure can enhance the recognition effect.The thesis finally points out the method of shallow seismic exploration under complex geological conditions,defects and suggestions of further research,especially the frequency attribute is added to the coherent noise after two-dimensional viscoelastic finite difference numerical simulation and seismic data,summarizes the fault after adding coherent noise wave field response characteristics and output of high resolution frequency attributessection to provide theory the basis for the subsequent engineering practice.