Tomographic velocity model building of the near surface with velocity-inversion interfaces: A test using the Yilmaz model

作者：Liu Hui^*; Zhou Hua wei; Liu Wenge; Li Peiming; Zou Zhihui

来源：Geophysics, 2010, 75(6): U39-U47.

DOI：10.1190/1.3502665

• Environmental studies
• Model parameterization
• Multiscale schemes
• Near surface velocity model
• Oil and gas exploration
• Tomographic velocity
• Travel time tomography
• Velocity inversion

First-arrival traveltime tomography is a popular approach to building the near-surface velocity models for oil and gas exploration, mining, geoengineering, and environmental studies. However, the presence of velocity-inversion interfaces (VIIs), across which the overlying velocity is higher than the underlying velocity, might corrupt the tomographic solutions. This is because most first-arrival raypaths will not traverse along any VII, such as the top of a low-velocity zone. We have examined the impact of VIIs on first-arrival tomographic velocity model building of the near surface using a synthetic near-surface velocity model. This examination confirms the severe impact of VIIs on first-arrival tomography. When the source-to-receiver offset is greater than the lateral extent of the VIIs, good near-surface velocity models can still be established using a multiscale deformable-layer tomography (DLT), which uses a layer-based model parameterization and a multiscale scheme as regularization. Compared with the results from a commercial grid-based tomography, the DLT delivers much better near-surface statics solutions and less error in the images of deep reflectors.

• 出版日期2010-12