Integrated Seismic Feasibility Workflow:Elastic Modeling Approach In A Complex Near Surface Area

摘要

The objective of this study is to assess the most appropriate seismic acquisition parameters and processing workflow in a complex near surface area characterized by presence of extreme topography,boulder- strewn canyons and shallow fracture systems.Proper simulation of this harsh topographic and geological environment,through an elastic modeling approach,is implemented into an integrated feasibility study to identify the main effects in the seismic response. The consequent evaluation and analysis reproduce the main issues related to processing,useful to identify reliable acquisition template and processing key-steps able to support better imaging for explorative targets in the area.The scope of elastic modeling is to simulate the effect on seismic of a system of aligned fractures,areal scatterers and canyons,located in the near surface of the future survey area.Anisotropic elastic modeling was accomplished through a finite difference(FD)code,generating the possible seismic response in terms of vertical and horizontal components(P-wave and PS-wave seismic data).The parameters and the geophysical model,input to the modeling exercise,were defined on the basis of in-place data measurements and observations(logs,outcrops,vintage seismic,etc.). Synthetic seismic was then carefully analyzed in order to infer considerations about the geophysical problem generated by such an environment,with particular attention to surface wave generation,scattered and mode converted energy,anisotropic behavior.Denoise tests were implemented in order to identify the most effective acquisition parameters and a possible future processing strategy.The integration of the achieved results demonstrated that seismic data and the quality signal are strongly affected by the presence of canyons,in terms of diffractions and scattering;the fracture system amplifies the noise in the data, increasing the scattering effect. An appropriate acquisition template is then proposed to reduce the noise level in the recorded data. Processing steps are also recommended to face the geophysical issues in such surface and near-surface complexities.