A method for electrical survey of hydrocarbons deposits under seabed depths up to 1500 m and equipment therefor are provided. The equipment includes a vessel, a generator, an excitation field block, connected with a vertical dipole with coax electrodes, a data registration/processing block, bottom systems with. The lower dipole electrode is situated at maximally 100 m from the seabed, the upper electrode at maximally 200 m from the surface. The operation of the generator and bottom systems is synchronized the dipole is submersed into the sea, and fed with alternating-sign rectangular current pulses, whose on-off time ratio and duration are programmably determined. The bottom systems register reflected signals and electromagnetic field components, when the dipole's current is on and off. Analysis of the signals accounts modifications of primary and secondary fields, transient field changes for determination of the environment resistivity and strata polarization characteristics thereby improving the hydrocarbons deposits prognosis.