Abstract
Spatial sampling, finite bandwidth, and overlying-strata shielding are three key issues to affect the spatial resolution of seismic imaging for deep targets. Some factors have a great impact on the horizontal resolution, whereas others influence the vertical resolution. How to quantify these effects remains controversial for complex media. Most previous studies on seismic acquisition geometries focus on the horizontal resolution for layered media but neglecting to measure the vertical resolution especially in complex media. Conventional criteria for vertical resolution are based on the theory of geometric seismology with the assumption of a simple medium. As a practical alternative for resolution estimation in complex media, numerical methods with wavefield extrapolation for focal-beam analysis can provide comprehensive insight into the combined effect of acquisition geometries, bandlimited frequencies, and complex media on the horizontal and vertical spatial resolutions of acquisition geometries. We incorporate some classic criteria into the focal-beam numerical analysis to measure the spatial resolutions. Four parameters are used to quantify the performance of acquisition geometries. The horizontal (vertical) resolution is defined as the main-lobe width of a focal beam along the horizontal (vertical) direction, whereas the square root of the peak-to-total ratio of energies is referred to as the horizontal (vertical) sharpness. These parameters describe the horizontal and vertical spatial resolution and sharpness to image the target. Numerical examples with typical acquisition geometries demonstrate the performance of numerical resolution analyses in complex media.
Highlights
Spatial sampling characterization of seismic acquisition geometries is a rapidly growing area of research because of its impact on seismic imaging
Computation of the resolution matrix δx B consists of the following steps, (1) Select a target point at located at depth zm. (2) Simulate forward propagation from the target point to the surface located at depth z0 to obtain the wavefield wk (z0, zm) and apply the acquisition geometry to select traces corresponding to source and receiver matrices D (z0) and S (z0)
We can improve the accuracy of focal-beam analyses by reducing the depth-step size for wavefield extrapolation and computing more single-frequency beams for interpolation but at the cost of computational efficiency
Summary
Spatial sampling characterization of seismic acquisition geometries is a rapidly growing area of research because of its impact on seismic imaging. Numerical methods with wavefield extrapolation for focal-beam analysis are modified to investigate the combined effect of acquisition geometries, band-limited frequencies, and complex media on both the horizontal and vertical resolutions. (2) Simulate forward propagation from the target point to the surface located at depth z0 to obtain the wavefield wk (z0, zm) and apply the acquisition geometry to select traces corresponding to source and receiver matrices D (z0) and S (z0). The VS is computed as the square root of the ratio of the peak energy to the total energy of the vertical profile These characteristic parameters quantify the horizontal and vertical resolutions and their sharpness of an acquisition geometry for seismic imaging at the target. For the computational stability of HS and VS values, the meshing spacing should meet the needs of HR and VR calculation as previously mentioned, and the meshing range around the target should be large enough to ensure the wavefield amplitude reduced enough toward the border, less than 0.1% of the maximum amplitude
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
