Abstract: There is described apparatus for orienting at least one electromagnetic field sensor, a related receiver unit and method of use. The apparatus has an orientation detector having an output which is dependent upon an orientation of the electromagnetic field sensor, an actuator and a controller which is arranged in communication with the orientation detector and the actuator, the controller being configured to be operable to generate at least one instruction for operating the actuator for moving the electromagnetic field sensor into a predefined orientation, in dependence upon the output from the orientation detector.

Abstract: A vertical receiver antenna device includes first and second receiving, electrode units interconnected by a receiver antenna cable and connected to means for the electromagnetic surveying of electrically resistive targets potentially containing hydrocarbons. The receiver antenna is arranged in a tubular, non-magnetic antenna housing arranged vertically in subsea uncompacted material, and one of the first and second receiving electrode units being connected in a electrically conductive manner to the underlying structure, and the other one of the first and second receiving electrode units being arranged in a portion of the antenna housing distantly from the first one of first and second receiving electrode units.

Abstract: A device for disposing an antenna dipole arranged to be submerged in a water mass is described. A first electrode is placed, in an operative position, approximately vertically above and at a distance from a second electrode. A mast is pivotally secured, at a portion distant from, in the operative position, a lower end portion, to a stand. The first electrode is arranged near, in or on an upper end portion of the mast. The second electrode is arranged near, in or on the lower end portion of the mast. The mast and/or stand includes means which are arranged to keep the mast in a prescribed position. The mast and stand are formed substantially of non-magnetic materials.

Abstract: A method is proposed for a marine electromagnetic survey based on the TM mode, for the purpose of prospecting for and detecting subsurface hydrocarbon reservoirs. The method includes an electromagnetic field source (1113) that, in a submerged, essentially vertical transmitter antenna, generates and injects electric current pulses (81,82) with a sharply defined termination. An electromagnetic field generated by these pulses (81,82) is measured by at least one receiver (1109) provided with an essentially vertical receiver antenna (1111) submerged in water, during the interval when the current in the transmitter antenna (1108) of the electromagnetic field source (1113) is switched off. The distance between the electromagnetic field source (1113) and the at least one receiver (1109) is smaller than the depth of the target object. An apparatus is also described, for implementation of the method.

Abstract: A sensor (S) for marine measurements of an electric field, the sensor (S) including at least two electrodes (3, 4); signal transmission means (5) for transmitting measured signals from the sensor (S) to a signal processing (6); at least two closed containers (1, 2) which are formed of a non-conductive material and are filled with an electrolyte (E); at least two flexible hoses (7, 8) formed of an electrically non-conductive material; there being attached in a fluid-communicating manner to each of the containers at least one first hose end (7a, 8a), and a second hose end (7b, 8b) being open and attached to means (9a, 9b) for exact positioning of the second hose end (7b, 8b); the hoses (7, 8) being arranged to be filled with a medium (W) of the same type as that, in which the sensor (S) is arranged to be immersed in an operative condition; and two containers (1, 2) forming a pair of containers, the two containers (1, 2), relatively, being placed close to each other under approximately identical thermal, pressur

Abstract: A sensor (S) for marine measurements of an electric field, the sensor (S) including at least two electrodes (3, 4); signal transmission means (5) for transmitting measured signals from the sensor (S) to a signal processing (6); at least two closed containers (1, 2) which are formed o a non-conductive material and are filled with an electrolyte (E); at least two flexible hoses (7, 8) formed of an electrically non-conductive material; there being attached in a fluid-communicating manner to each of the containers at least one first hose end (7a, 8a), and a second hose end (7b, 8b) being open and attached to means (9a, 9b) for exact positioning of the second hose end (7b, 8b); the hoses (7, 8) being arranged to be filled with a medium (W) of the same type as that, in which the sensor (S) is arranged to be immersed in an operative condition; and two containers (1, 2) forming a pair of containers, the two containers (1, 2), relatively, being placed close to each other under approximately identical thermal, pressure