For all the benefits of seismic, ambiguities still exist - particularly in regard to AVO responses caused by fluid or lithological variations with a potentially negative impact on well placement. There is often a risk that a well may encounter a paleo fluid contact or the reservoir has variable quality. Both cases will be reflected in the CSEM results, as the CSEM data response is directly dependent on the hydrocarbon saturation.
A combination of CSEM and seismic reduces ambiguity, which leads to optimized well placement.
Example of dry wells drilled outside CSEM anomalies. Obviously, there are other locations which would be more likely to result in a discovery, similar to the discovery well.