oa Dealing with complexity of the interpretation of marine controlled source EM surveys.

Subsurface resistivity mapping based on Controlled Source Electromagnetic (CSEM) measurements are attractive for Shell because they offer the possibility to distinguish between hydrocarbon and brine bearing reservoirs where conventional seismic methods are sometimes inconclusive. Indeed, the resistivity of a reservoir rock is directly related to the amount and type of fluid filling the pores while its acoustic properties are rather insensitive to it. CSEM can therefore be a valuable tool to compliment seismic data for prospect evaluation. In Shell, we have applied the CSEM method on a worldwide scale since 2003 to both de-risking and portfolio polarization in a marine settings.