METHOD OF NAVAL GEOLOGICAL SURVEY BASED ONTO FOCUSING OF ELECTRIC CURRENT (VERSIONS) Russian patent published in 2006 - IPC G01V3/06 

FIELD: geophysics; sea geological prospecting.

SUBSTANCE: method uses controlled artificial electromagnet field sources. Electromagnetic filed is excited in tested medium by sending into it two similar rectangular current pulses: one when probing installation passes through profile of survey and the other one - at backward direction. Profile can be made in form of circle or straight line. Instant values of first and second differences of electric potentials are measured between current pulses during pauses all along length of transient process signals. Along whole duration of any pause, two instant values of first and second differences of electric potentials are selected, which values are disposed close to each other in time and differences of the values are measured. Result of axial difference of electric potentials along profile are provided to be equal to zero to exclude axial component of current density under point of probing and coefficient of focusing is determined. Three multiplicities of normalized electric parameters are calculated from values of the differences while taking focusing coefficient into account. Reverse task is solved on the base of differential equation of math physics by using received parameters for strength of dipole source in electrochemically polarized conducting medium. Model of medium is found which model is closest in geometrical structure and in electric parameters to tested one. Time sections of the model are built on the base of electric parameters included into the equation as electric conductivity of medium, coefficient of induced polarization and induced polarization potential difference pulse decay time constant.

EFFECT: elimination of arm effect; ability of separating electric conductivity parameters and induced polarization.

2 cl, 5 dwg