SYNTHETIC VERTICAL ELECTROMAGNETIC SOURCE

摘要

A method for surveying a subsurface using electromagnetic signals, comprises: using at least one dipole to transmit into the subsurface a series of signals that includes pairs of opposing electromagnetic signals, using at least one receiver to receive from the subsurface a set of signals resulting from passage of the transmitted signals through the subsurface, locating within the set of received signals at least one pair of received signals having opposite field directions, and processing said pair of opposing received signals so as to obtain information about the subsurface. The transmitting dipole can be an alternating dipole towed above the seafloor and may be towed along non-parallel lines or along orthogonal grid lines. A plurality of pairs of received signals having a common center point may be processed and phase shifting and/or amplitude modulation can be used to steer said information. A listening period can be included between transmitted signals.