In-line and broadside marine electromagnetic surveying

摘要

Methods for geophysical surveying include disposing an electromagnetic source and first and second receiver electrodes in water; actuating the source; and detecting a responsive electromagnetic field by measuring a potential difference between the first and second receiver electrodes, wherein: the electromagnetic source defines a source dipole axis; the first and second receiver electrodes define a receiver dipole axis; and the source dipole axis is not substantially parallel to the receiver dipole axis. Systems for geophysical surveying include a first source electrode on a first source cable; a second source electrode on a different second source cable, the first and second source electrodes forming an electromagnetic source and defining a source dipole axis; a first receiver electrode on a first receiver cable; a second receiver electrode on a different second receiver cable, the first and second receiver electrodes defining a receiver dipole axis not substantially parallel to the source dipole axis.