Abstract: A system for detecting or determining the nature of a subterranean reservoir. An electromagnetic field is applied using a dipole antenna transmitter and this is detected using a dipole antenna receiver. The measurements are taken with the antenna both in-line and parallel and the difference between the two sets of measurements is exploited. A characteristic difference indicates a high resistive layer, which corresponds to a hydrocarbon reservoir.

Abstract: A system for determining the nature of a subterranean reservoir 12 whose position and geometry is known from previous seismic surveys. An electromagnetic field 24, 25, 26, 27 is applied by a transmitter 18 on the seabed 14 and detected by antennea 21, 22, 23 also on the seabed 14. The nature of the detected reflected waves 25, 26, 27 is used to determine whether the reservoir 12 contains water or hydrocarbons.

Abstract: A device for detecting changes of resistivity or dielectrical properties due to changes of fluid composition in the near-well area about a well in a geological formation, comprising an electrically conductive tubing string, an electrical energy source, a signal generator, at least one transmitting antenna for emitting electromagnetic waves along the tubing string, one or more receiver antennas for receiving electromagnetic waves reflected along the tubing string, devices for receiving signals induced in the receiver antennas, signal processing means for processing the received signals, and communication devices for transmitting signals representing the electrical signals and for receiving control signals.

Abstract: A system for investigating subterranean strata. An electromagnetic field is applied using a dipole antenna transmitter and this is detected using a dipole antenna receiver. Phase information is extracted from a refracted wave response and used to identify the presence and/or nature of a subterranean reservoir.

Abstract: A system for investigating subterranean strata. An electromagnetic field is applied using a fixed dipole antenna transmitter and this is detected using a dipole antenna receiver. The receiver is moved from one location to another in dependence upon the strength of the detected signal.

Abstract: A system for detecting a subterranean reservoir or determining the nature of a subterranean reservoir 12 whose position and geometry is known from previous seismic surveys. An electromagnetic field 24, 25, 26, 27 is applied by a transmitter 18 on the seabed 14 and detected by antenna 21, 22, 23 also on the seabed 14. A refracted wave component is sought in the wave field response, to determine the nature of any reservoir present.

Abstract: A method for detecting electrical properties in a geological formation in a well which has within it a tubing string comprising the steps of mounting a transmitter antenna outside of the tubing string in a fixed position with respect to the geological formation, mounting a receiving antenna outside of the tubing string in a fixed position with respect to the geological formation, generating a first series of electromagnetic waves at a first time, receiving a first series of reflected electromagnetic waves in the receiver antenna, transforming the first series of reflected electromagnetic waves to form a first registration, generating a second series of electromagnetic waves at a second time, receiving a second series of reflected electromagnetic waves in the receiver antenna, transforming the second series of reflected electromagnetic waves to form a second registration, and comparing the registrations. Also disclosed is a device for accomplishing the method.

Abstract: The invention is a device for measuring and surveillance of resistivity in a petroleum reservoir in a geological formation with an injection-, observation- or production well comprising an electrically conductive metallic well tubing, with the new and inventive being characterized by the following features: a) an electrical energy source; b) at least one inductive transmitter antenna for electromagnetic waves, fixedly arranged in the well, outside of the well tubing's outer metallic surface; c) at least one series of sensors comprising n inductive resistivity sensors (5a, 5b, . . . , 5n) arranged for receiving the electromagnetic waves and generation of measurement signals, fixedly arranged in the well, by the petroleum reservoir and outside the well tubing's outer metallic surface; and d) a signal conductor for the measurement signals.