Patent ID: 7430474

Claim:
A method of performing surveying of a subterranean structure, comprising: determining electromagnetic (EM) wavefields traveling in opposite directions; defining a relationship among the EM wavefields, wherein the EM wavefields include a first set of EM wavefields in a first state in which a sea surface is present, and a second set of EM wavefields in a second, different state in which the sea surface is not present, wherein the first set of EM wavefields comprises EM wavefields traveling in opposite directions, and wherein the second set of EM wavefields comprises EM wavefields traveling in opposite directions; receiving measurements in response to: (1) EM wavefields produced by an EM transmitter at plural different orientations; or (2) EM wavefields produced by different types of EM transmitters; and according to the measurements, solving for at least one EM wavefield in the relationship to perform removal of sea surface-related effects.