College of Geo-exploration Science �� Technology��Jilin University��Changchun 130026��China

We studied the feasibility of frequency domain submarine electromagnetic method in the exploration of oil and gas�� In order to distinguish the spatial reservoir filled with hydrocarbon��we established three-dimensional seabed models with a horizontal electric-dipole source�� With numeric forward simulation of models by vector finite element method��it shows that: the MCSEM can well identify hydrocarbon layers; while it is difficult to recognize reservoir in the shallow water which was concluded by the normalized amplitudes of deep water and shallow water; and with higher frequency��the identifiying ability will be better within experiment frequencies�� The results prove that the identification of hydrocarbon layers by the MCSEM was established on the basis of the theoretical guided wave��