Leveraging anisotropic workflows in changing times: Two case studies from the eastern Gulf of Mexico

Abstract

In the pursuit of ever improved imaging in the Gulf of Mexico a number of trends in velocity model-building workflows appear to be emerging. A first trend has been the shift towards increasingly more complex anisotropic as part of prestack depth migration (PSDM) workflows. A good example is the move from vertical transverse isotropy (VTI) imaging to tilted transverse isotropy (TTI) imaging in complex areas. Another trend, particularly in production settings, is the growing requirement for delivery of seismic images that tie all available well data together with an understanding of the uncertainty associated with that image. A final trend is the realization that additional drilling regulations are likely to require a much more thorough understanding of the shallow section. A flexible model-building workflow is therefore needed that can be tailored depending on project objectives and the availability of additional data. Such a workflow would allow for a proactive approach in anticipation of additional regulations, while maximizing the value that can be derived from the velocity model. In this paper we present two case studies from the eastern Gulf of Mexico with different degrees of geological complexity and project objectives. We illustrate the use of a flexible and adaptable workflow for anisotropic model building and suggest the trends that such a workflow may capture in the future.

Improved subsalt imaging and salt interpretation by RTM scenario testing and image partitioning

“…With more advanced algorithms comes the requirement for earth models with even greater resolution and accuracy. TTI anisotropic model building workflows using well constrained tomography to build the supra-salt velocity model were described by Zdraveva et al (2011), andO'Briain et al (2011) and play an important role in correctly positioning the top salt reflector. Fullwaveform inversion (FWI) can also be added to further refine the model (Vigh et al 2011).…”