Near-surface seismic imaging using first arrival time inversion with pre-stack depth migration

This paper presents a hybrid acquisition strategy for imaging near surface stratigraphy. Shallow seismic depth imaging studies typically involve data processing followed by velocity estimation and migration. Most researchers apply the commonly used conventional processing (stacking velocity analysis) for velocity model building that in turn is used in migration. However, we find that when it comes to shallow imaging, the conventional processing lacks accuracy in velocity model estimation, which consequently leads to poor quality in depth image. To improve the velocity model reliability, we followed an unconventional procedure: first arrival inversion combined with prestack Kirchhoff depth migration. We demonstrate the imaging application for an ultra shallow (<15m) geological target, which is a set of paleo-channels in the Bull Creek, Beaver County, Oklahoma. To demonstrate the concept two coincident profiles were acquired - one targeted towards inversion and the other towards migration. Besides migrating data with the inversion model, we also migrate the data with velocity model developed though conventional processing. We compare the results to illustrate that significant improvements can be made in imaging of the shallow subsurface by using velocity models created by traveltime inversion.