Improving Gather Picking for Tomography in Complex Velocity Models, a Case Study on Shale Diapirs

We present a case study demonstrating that in a complex geological setting travel time tomography can produce high resolution velocity fields without resorting to the use of simplified blocky velocity models to represent the complex velocity field where there is poor seismic imaging. We developed a strategy to enhance the travel time picking which allows the reliable use of small spatial smoothing in the tomographic inversion and produces a stable complex velocity field which significantly improves the deeper imaging. The study area overlies the Vema Dome (offshore Norway) containing irregular structured shale diapirs in the shallow section. These diapirs are possibly cored by diatomaceous oozes deposited during the Paleocene and Miocene periods which results in rapid large velocity changes.