Predicting horizontal resistivity trends: An example from the Barents Sea

Abstract

Exploring the major controlling factors on resistivity depth trends in sedimentary basins is an interesting subject from both scientific and commercial perspectives. We propose a rock-physics based workflow for predicting the horizontal resistivity depth trends through integration of the Waxman-Smits model and in-situ subsurface conditions such as temperature and salinity. The workflow consists of two steps: First, we exploit the lithological variations among major stratigraphic group units by utilizing log data from wells within a given basin. Then, in this same resolution, we apply a forward modeling to predict the 1-D horizontal resistivity depth profile at any appointed location in the basin. In this abstract, we will demonstrate our workflow using well data from the Norwegian Barents Sea, and present the predictability through comparison against a real horizontal resistivity log measurement. By far, we have tested the workflow using well logs across the Norwegian Continental Shelf (NCS) - the North Sea, Norwegian Sea and the Barents Sea. Our predictions capture the overall resistivity depth trends successfully in all selected wells within each individual basin. We also expect the workflow to have the same performance in basins outside of NCS. The predicted resistivity depth profiles can be used as a priori models in controlled source electromagnetic (CSEM) data inversion schemes, or to provide ‘what if’ scenarios as part of the reservoir property analysis and risk assessment in an exploration phase.