ИСТИНА

This invention is directed toward an electromagnetic surveying method based on detection of induced polarization effect and evaluation of its characteristics for mapping marine hydrocarbon targets. The method includes the steps of vertical deployment in a body of water of at least one electric wire which forms an electromagnetic transmitter which emits electromagnetic energy arranged to excite an electromagnetic field in the body of water and underlying medium, the same wire being used as a receiver for measurements of the vertical component of the electric field: (b) providing survey data as the spatial distribution of the vertical component of the elec¬tric field and the medium response in the form of apparent resistivity versus time in the body of water, (c) performing a space time analysis of the vertical component of the electric field and response with the purpose of detecting induced polarization effect and determine its intensity and relaxation times: and (d) mapping the anomalous zones described by the characteristics perspective of the induced polarization for the exploration of an underground hydrocarbon reservoir. There is also described equipment for use when practising the method.