Hydrocarbon saturation is an important parameter for evaluating a prospect. While resistivity is sensitive to high saturations, seismic velocities do not differ significantly between high and low saturation (e.g. fizz gas). This is one of the largest uncertainties when running AVO studies on seismic data.
Resistivity in a reservoir, however, is strongly dependant on saturation. Furthermore, the strength of a resistive CSEM anomaly is a function of the volume of hydrocarbons creating it.
Therefore, CSEM data in many cases will not image a resistive anomaly due to non-commercial accumulations of hydrocarbons.
CSEM data will in this way be an important tool in the assessment of a prospect.