Improved Imaging in the Dutch Sector of the North Sea by Global CIP Tomography with Geological Constraints
M. Yanez, O. Zdraveva, M. Woodward, N. Hutchinson, M. Jarvis and P. Whitfield
Event name: 77th EAGE Conference and Exhibition 2015
Session: Seismic Imaging - Case Histories II
Publication date: 01 June 2015
Info: Extended abstract, PDF ( 4.69Mb )
Price: € 20
Due to the presence of high velocity contrast boundaries in the geological section, the standard practice for model building and updating in the North Sea has been to use models with explicit surfaces and perform tomography layer by layer (layer stripping). Often called hybrid tomography, this method is both time-consuming and prone to velocity errors becoming sealed into the shallow layers as the process moves deeper. More recently multilayer tomography schemes have been proposed as an alternative, but they still require significant interpretation effort and boundaries for reflective geological units to be explicitly present in the model. In this paper, we present a case study from the Dutch sector of the North Sea using a global common image point (CIP) tomography with geologic constraints to enable faster convergence over all model space with a reduced number of iterations and reduced human intervention. In this approach, all geological layers beneath the water bottom are treated as a single zone being updated during tomography. We contrast our results with a hybrid tomography approach and show that the new method produces a geologically consistent model, which better explains the seismic and well data and yields to final images with improved focusing and interpretability.