Patent ID: 8239181

Claim:
A method for transforming controlled source electromagnetic (“CSEM”) survey data acquired from a subsurface region to a resistivity model of the subsurface region indicating hydrocarbon presence or absence, comprising: (a) constructing an initial discrete resistivity model of the subsurface region and determining one or more regions in said initial discrete resistivity model, below source or receiver locations, wherein electromagnetic data have relatively low or fluctuating sensitivity to resistivity changes in such one or more regions, called anomalous sensitivity regions; (b) performing inversion of the survey data to generate an update to the initial resistivity model; (c) modifying the model update to selectively mitigate sensitivity effects in the anomalous sensitivity region or regions of the model without affecting other regions of the model, wherein said selectively mitigate sensitivity effects is designed to reduce influence on the anomalous sensitivity region or regions of the model due to survey data associated with the nearest receiver or source; and (d) applying the modified update to transform the initial model to an updated model having suppressed measurement system artifacts; (e) using the updated resistivity model to predict whether the subsurface region contains an accumulation of hydrocarbons.