Advances in quantitative model-assisted seismic interpretation

Håvar Gjøystdal, Åsmund Drottning, Isabelle Lecomte, and Mike Branston* of NORSAR Innovation, introduce a modelling concept that aims to provide users with the tools to make a quantitative interpretation of their seismic data. Today’s seismic interpretation and attribute analysis is performed at many levels in the E&P cycle – from structural horizon picking in early exploration, to advanced 4D reservoir studies during petroleum production. In many cases the interpretation process is simply a systematic collection of seismic attributes (e.g. horizon/attribute tracking) without any direct relation to a particular model behind. In more advanced interpretation, it can be very fruitful to relate the interpretation to a well-defined geo-model representation. We have developed a new software tool (SeisRoX) based on the idea that such a geo-model should always exist. In this context, the geo-model is defined as a spatial representation of geophysical and geological properties in a certain volume of the subsurface, containing sufficient information to allow a simulation of the seismic response of that model which includes external constraints, such as survey geometry and source signature. The seismic response will usually have different meanings depending on its intended use. It could, for example, be calculated traveltimes or simulations of seismic data in prestack or poststack domains. Seismic response is a simulated migrated seismic cube, or seismic attributes deduced from such a cube as this is the usual working domain for most interpreters.