ELECTROMAGNETIC SOUNDING METHOD USING A TRANSIENT FIELD SPATIAL DERIVATION ON SEVERAL SEPARATIONS

摘要

The invention relates to electromagnetic prospecting and is used for surface and marine electromagnetic sounding by means of controllable electromagnetic field sources and is applied in a package oil and gas prospecting works for searching and outlining oil and gas fields. The inventive method is based on the selection of a response from earth materials which are secondary modified by hydrocarbons migration. Said invention makes it possible to ensure a set of processing technologies enabling to layer-by-layer determine an electrical resistivity and process characteristics of a medium induced polarisation: a polarizability coefficient, a time constant and a relaxation spectrum width. The inventive method consists in carrying out a measurement by several receiving lines, wherein the position of two feeding lines of a sounding plant is substantially symmetrical with respect to the receiving lines which are located within a 30° sector from the feeding line extension, in recording a transient signal by land axial-dipole sounding devices or by marine sounding devices associated with a continuous signal recording during a ship travel and in calculating the population of interpretable parameters P 1 DÕ, ”U H , P s using recorded potential difference curves (”U(i), ” 2 U(i)) which are preliminary processed, contracted in the form of time gates and differentiated.