METHOD FOR MARINE GEOELECTRICAL EXPLORATION WITH ELECTRICAL CURRENT FOCUSING Russian patent published in 2010 - IPC G01V3/06 G01V3/15 

FIELD: physics.

SUBSTANCE: invention relates to marine geoelectrical exploration using controlled artificial sources of electromagnetic field. Using a dipole source, an electromagnetic field is generated inside the analysed medium by sending rectangular electric pulses with intervals in between into the medium. Geometrical probing is done along the profile during the current pulse, and probing on transient processes is done during the interval. Measurements are taken using measuring apparatus mounted on the seafloor, consisting of five electrodes: a central electrode with four others around it on corners of a square, two opposite sides of which are parallel to the axis of the profile. During the current flow period and intervals between current pulses, the second electric potential difference between external electrodes and the central electrode, as well as the first electric potential differences between three pairs of external electrodes is measured. When the dipole source passes through different points, there is provision for equipotentiality of a closed line passing through four external electrodes of the measuring apparatus thereby eliminating the horizontal component of current density in each probing point inside this line. Values of the measured electric potential differences are used to calculate three sets of standard interpreted electrical parametres which are not subject to lateral effect of three-dimensional geological non-uniformities located outside the probing point. Using the derived parametres, the model of the medium is found and time sections of this model is constructed on electroconductivity of elements of the medium, induced polarisation coefficient and decay time constant of induced polarisation potential differences.

EFFECT: elimination of distorting lateral effect on probing results, which allows for deep sea delineation of hydrocarbon accumulation with high contrast.

4 cl, 6 dwg