METHOD AND APPARATUS FOR HYDROCARBON DETECTION VIA EDDY CURRENTS INDUCED BY LARGE AMPLITUDE, LONG PERIOD, SQUARE WAVES

摘要

Method and apparatus for hydrocarbon detection via eddy currents induced by large amplitude. long period, square waves includes a transmitter (16) connected to transmission lines (12) which, in turn are connected to grounded electrodes (20) When energized the transmitter emits large amplitude, long period square waves of current which induce secondary eddy currents in the subsurface measurable at the surface with a magnetometer or an induction coil. The magnetic field changes are received and recorded as time-varying voltages at each sounding site by a receiver (26) and movable data receiving station (28). Information on resistivity variations of the subsurface formations is deduced from the amplitude and shape of the measured magnetic field signals plotted as a function of time and depth after applying appropriate mathematical equations.