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 system for marine electromagnetic surveying of hydrocarbon reservoirs is proposed. The system proposed is characterized by high sensitivity to targets containing hydrocarbons and an ability to work in shallow and deep waters. The system includes a transmitter setting up current pulses in water (2) through a submerged, vertical or horizontal transmitter cable (7a, 7b, 8) and a registration subsystem (9) connected to electrodes (11) on vertical or horizontal receiver cables (10a, 10b). The transmitter generates a special sequence of sharply terminated pulses of the electric current, the electric field being measured in the water in the pauses between these pulses. The straight line through the receiver electrodes lies in the same vertical plane as the terminations of the transmitter cable (7a, 7b).

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 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