In order to improve the efficiency of 3D near-surface velocity model building, we develop a layer-stripping method using seismic first-arrival times. The velocity model within a Common Mid-Point （CMP） gather is assu...In order to improve the efficiency of 3D near-surface velocity model building, we develop a layer-stripping method using seismic first-arrival times. The velocity model within a Common Mid-Point （CMP） gather is assumed to be stratified into thin layers, and the velocity of each layer var- ies linearly with depth. The thickness and velocity of the top layer are estimated using minimum-offset first-arrival data in a CMP gather. Then the top layer is stripped and the second layer becomes a new top layer. After removing the effect of the top layer from the former first-arrival data, the new first-arrival data are obtained and then used to estimate the parameters of the second layer. In this manner, the velocity model, being regarded as that at a CMP location, is built layer-by-layer from the top to the bottom. A 3D near-surface velocity model is then formed using the velocity models at all CMP locations. The tests on synthetic and observed seismic data show that the layer-stripping method can be used to build good near-surface velocity models for static correction, and its computation speed is approximately hundred times faster than that of grid tomography.展开更多
Full waveform inversion（FWI） directly minimizes errors between synthetic and observed data.For the surface acquisition geometry,reflections generated from deep reflectors are sensitive to overburden structure,so it ...Full waveform inversion（FWI） directly minimizes errors between synthetic and observed data.For the surface acquisition geometry,reflections generated from deep reflectors are sensitive to overburden structure,so it is reasonable to update the macro velocity model in a top-to-bottom manner.For models dominated by horizontally layered structures,combination of offset/time weighting and constant update depth control（CUDC） is sufficient for layer-stripping FWI.CUDC requires ray tracing to determine reflection traveltimes at a constant depth.As model complexity increases,the multi-path effects will have to be considered.We developed a new layer-stripping FWI method utilizing damped seismic reflection data,which does not need CUDC and ray tracing.Numerical examples show that effective update depth（EUD） can be controlled by damping constants even in complex regions and the inversion result is more accurate than conventional methods.展开更多
A layer-stripping method is presented for simultaneous inversion of compressional velocity and shear velocity in layered medium from single precritical-incident-angle data of P-P and P-SV plane wave seismogram. A fini...A layer-stripping method is presented for simultaneous inversion of compressional velocity and shear velocity in layered medium from single precritical-incident-angle data of P-P and P-SV plane wave seismogram. A finite bandwidth algorithm is provided and results obviously better than previous research work are obtained by the numerical experiments for band-limited seismogram and synthetic data including noise.展开更多
基金supported by the National Natural Science Foundation of China(Nos.41230318,41074077)the Specialized Research Fund for the Doctoral Program of Higher Education(No.20130132110023)the Fundamental Research Funds for the Central Universities of China(No.201413004)
文摘In order to improve the efficiency of 3D near-surface velocity model building, we develop a layer-stripping method using seismic first-arrival times. The velocity model within a Common Mid-Point （CMP） gather is assumed to be stratified into thin layers, and the velocity of each layer var- ies linearly with depth. The thickness and velocity of the top layer are estimated using minimum-offset first-arrival data in a CMP gather. Then the top layer is stripped and the second layer becomes a new top layer. After removing the effect of the top layer from the former first-arrival data, the new first-arrival data are obtained and then used to estimate the parameters of the second layer. In this manner, the velocity model, being regarded as that at a CMP location, is built layer-by-layer from the top to the bottom. A 3D near-surface velocity model is then formed using the velocity models at all CMP locations. The tests on synthetic and observed seismic data show that the layer-stripping method can be used to build good near-surface velocity models for static correction, and its computation speed is approximately hundred times faster than that of grid tomography.
基金supported by the National Natural Science Foundation of China (No. 40774062)
文摘Full waveform inversion（FWI） directly minimizes errors between synthetic and observed data.For the surface acquisition geometry,reflections generated from deep reflectors are sensitive to overburden structure,so it is reasonable to update the macro velocity model in a top-to-bottom manner.For models dominated by horizontally layered structures,combination of offset/time weighting and constant update depth control（CUDC） is sufficient for layer-stripping FWI.CUDC requires ray tracing to determine reflection traveltimes at a constant depth.As model complexity increases,the multi-path effects will have to be considered.We developed a new layer-stripping FWI method utilizing damped seismic reflection data,which does not need CUDC and ray tracing.Numerical examples show that effective update depth（EUD） can be controlled by damping constants even in complex regions and the inversion result is more accurate than conventional methods.
基金Project supported by the National Natural Science Foundation of China and General Corp. for Oil and Gas and Daqing Oilfield.
文摘A layer-stripping method is presented for simultaneous inversion of compressional velocity and shear velocity in layered medium from single precritical-incident-angle data of P-P and P-SV plane wave seismogram. A finite bandwidth algorithm is provided and results obviously better than previous research work are obtained by the numerical experiments for band-limited seismogram and synthetic data including noise.
