Imaging sea-bed sediment layers from echo data, which are collected by a system composed of a seismic profiler and a hydrophone streamer towed behind the profiler, is a way to reconstruct the structure of sedimeat lay...Imaging sea-bed sediment layers from echo data, which are collected by a system composed of a seismic profiler and a hydrophone streamer towed behind the profiler, is a way to reconstruct the structure of sedimeat layers with acoustic wav equation. The equation which describes the wave propagation is used for backward extrapolation of echo data observed at sea surface. When the medium is homogeneous or horizontally layered, time imaging approach is valid. However, in the case where a considerable lateral variation in velocity exists, the image section processed with the time approach does not represent the real structure, because of distortions caused by thin-lens effect similar as in optics. In this case, depth imaging approach must be used for both the time-shift correction of refraction terms and the convergence of diffractions simultaneously as wavefields are downward continued. As a result, the good image can be derived to determine the structure of sea-bed sediment layers.展开更多
Multiple prediction and subtraction techniques based on wavefield extrapolation are effective for suppressing multiple related to water layers. In the conventional wavefield extrapolation method,the multiples of the s...Multiple prediction and subtraction techniques based on wavefield extrapolation are effective for suppressing multiple related to water layers. In the conventional wavefield extrapolation method,the multiples of the seismic data are predicted from the known total wave field by the Green function convoluted with each point of the bottom. However,only the energy near the stationary phase point has an effect on the summation result when the convolutional gathers are added. The research proposed a stationary phase point extraction method based on high-resolution radon transform. In the radon domain,the energy near the stationary phase point is directly added along the convolutional gathers curve,which is a valid solution to the problem of the unstable phase of the events of multiple. The Curvelet matching subtraction technique is used to remove the multiple,which improved the accuracy of the multiple predicted by the wavefield extrapolation and the artifacts appearing around the events of multiple are well eliminated. The validity and feasibility of the proposed method are verified by the theoretical and practical data example.展开更多
文摘Imaging sea-bed sediment layers from echo data, which are collected by a system composed of a seismic profiler and a hydrophone streamer towed behind the profiler, is a way to reconstruct the structure of sedimeat layers with acoustic wav equation. The equation which describes the wave propagation is used for backward extrapolation of echo data observed at sea surface. When the medium is homogeneous or horizontally layered, time imaging approach is valid. However, in the case where a considerable lateral variation in velocity exists, the image section processed with the time approach does not represent the real structure, because of distortions caused by thin-lens effect similar as in optics. In this case, depth imaging approach must be used for both the time-shift correction of refraction terms and the convergence of diffractions simultaneously as wavefields are downward continued. As a result, the good image can be derived to determine the structure of sea-bed sediment layers.
基金Supported by the National Science and Technology Major Project(No.2016ZX05026-002-003)the National Natural Science Foundation of China(No.41374108)
文摘Multiple prediction and subtraction techniques based on wavefield extrapolation are effective for suppressing multiple related to water layers. In the conventional wavefield extrapolation method,the multiples of the seismic data are predicted from the known total wave field by the Green function convoluted with each point of the bottom. However,only the energy near the stationary phase point has an effect on the summation result when the convolutional gathers are added. The research proposed a stationary phase point extraction method based on high-resolution radon transform. In the radon domain,the energy near the stationary phase point is directly added along the convolutional gathers curve,which is a valid solution to the problem of the unstable phase of the events of multiple. The Curvelet matching subtraction technique is used to remove the multiple,which improved the accuracy of the multiple predicted by the wavefield extrapolation and the artifacts appearing around the events of multiple are well eliminated. The validity and feasibility of the proposed method are verified by the theoretical and practical data example.
