Fremgangsmåte og apparat for detektering av underjordiske formasjoners egenskaper

摘要

A method of investigating subterranean reservoirs comprises the steps of deploying an electromagnetic dipole transmitter and receiver 15,16 in the vicinity of the surface of the earth (e.g. on seabed 13), applying an electromagnetic field, preferably at a frequency of around 1Hz, using the transmitter and detecting the response of the underlying formations using the receiver. Phase information is extracted from the received signals and used to identify the presence, boundaries and/or nature of a subterranean reservoir 17.