METHOD OF SEA GEO-ELECTRO-SURVEY WITH ELECTRICAL FOCUSING (VERSIONS) Russian patent published in 2009 - IPC G01V3/06 

FIELD: mining.

SUBSTANCE: in three suggested versions of method electromagnetic field is exited in thickness of surveyed medium by sending into it rectangular pulses of current with intervals. Geometric probing is performed within the current pulse, and probing in transitive processes is performed within a pause. Also instantaneous values of the first and the second differences of electric potentials on the sea bottom are measured. Under the first version of the method three parallel profiles are laid. The medium profile is a measuring one; it passes through the probing point fixed on the sea bottom. Two other profiles are designed for transit of horizontal dipole source in a near bottom zone. The second axial and orthogonal differences of electric potentials are measured as well as differences of an axial, orthogonal and one any of four possible segmented between the two nearest exterior measuring electrodes differences of electric potentials are measured. There is provided the condition of equality to zero of resulting difference of electric potentials: axial, orthogonal and one of any segmented for exclusion of a horizontal component of current density in the point of probing. Two sets of normalisable interpretive electric parameters are calculated from values of the above said differences, considering these two sets are not influenced by side effect of three dimensions geologic non-uniformities located beyond the point of probing. Using obtained parameters an inverse problem is solved on the base of differential equation of mathematical physics for electrical field intensity of dipole source in electrochemical polarising conductive medium. Time-base sections are graphed on electro-conductivity of the medium, on coefficient of caused polarisation and on the constant of the period of fall of caused polarisation potential difference.

EFFECT: complete excluding horizontal constituent of current density in point of probing, excluding effects of side non-uniformities.

4 cl, 8 dwg