Electromagnetic sounding method using a transient field spatial derivation on several separations

Abstract

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. The 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 positionof two feeding lines of a sounding plant is substantially symmetrical with respect to the receiving lines which are located within a 30 DEG sector from the feeding line extensions, 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 interpretableparameters P1, deltaDphi, UH, Ps using recorded potential difference curves(deltaU(i) is less than 2, and 2 is more than deltaU(i))which are preliminary processed, contracted in the form of time gates and differentiated.

Description

Technical field

[0001] The invention belongs to the category of electrical exploration. This method uses a controllable electromagnetic field source, which is used in the comprehensive exploration work of exploring and delineating oil and gas deposits according to the secondary change response of the rock under the action of hydrocarbon migration. It can be used for both ground exploration and ocean exploration. The use of the invention can ensure that a series of technical methods are adopted for the layered measurement of unit resistance and the measurement of indicators of the polarization excitation process of the medium, such as the polarization coefficient, time constant, and spectral relaxation width. Background technique

[0002] The currently known geoelectric exploration methods, whether based on artificial electromagnetic fields or natural electromagnetic fields, are to measure the layer-by-layer distribution of unit resistance, that is, resistivity method. These meth...

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