Abstract: Techniques are described for measuring gravity using towed streamers. In an embodiment, a towed streamer apparatus comprises a plurality of micro electro-mechanical system (MEMS) sensors. One or more MEMS sensors of the plurality of MEMS sensors are configured to generate gravity measurement data. The one or more MEMS sensors transmit a digitized version of the gravity measurement data to a processing unit. In another embodiment, an apparatus is configured to receive gravity measurement data via an interface that is communicatively coupled to a plurality of MEMS sensors in at least one towed streamer. The apparatus may further be configured to combine the gravity measurement data received from the plurality of MEMS sensors to compute a target gravity measurement value and detect changes in gravity based on the target gravity measurement value.

Abstract: Systems and methods for marine seismic surveying of strata beneath a seafloor are disclosed, including, in certain aspects, locating an under water sensor cable with sensing apparatus on a seafloor beneath water; the cable having a first end connected to a first unmanned powered vehicle and a second end connected to a second unmanned powered vehicle; and, with the two vehicles, locating, moving, re-locating, raising, and/or maintaining tension on the cable. This abstract is provided to comply with the rules requiring an abstract which will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure and is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims, 37 C.F.R. 1.72(b).

Abstract: An electromagnetic survey sensing device includes at least two electrodes disposed at spaced apart locations. An electrical to optical converter is electrically coupled to the at least two electrodes. The converter is configured to change a property of light from a source in response to voltage imparted across the at least two electrodes. The device includes an optical fiber optically coupled to an output of the electrical to optical converter, the optical fiber in optical communication with a detector.

Abstract: A marine seismic streamer steering device comprises a body connected between two adjacent sections of the seismic streamer, at least one inlet port on the body, a plurality of outlet ports on the body, and a port control unit which controls water flow through the plurality of water outlet ports. The steering device further comprises a roll sensor which determines rotational orientation of the body and transmits the orientation to the port control unit, a lateral position sensor which determines lateral position of the body and transmits the lateral position to the port control unit, and a depth sensor which determines depth of the body and transmits the depth to the port control unit. The port control sensor then controls the water flow through the plurality of outlet ports based on the transmitted rotational orientation, lateral position, and depth of the body.

Abstract: The invention disclosed is a drive assembly for acoustic sources having sound emitting surfaces (1) adapted to be excited into vibrational motions. The invention is especially for use in seismic surveys. The drive assembly includes an electric rotational motor with at least one associated axle comprising at least an axle part (18) and a number of rods (21, 22) arranged radially in relation to the axle. The inner ends of the rods (21, 22) are influenced by the axle part (18) and the outer ends of the rods (21, 22) are adapted to excite the sound emitting surfaces (1) into vibrational motion. The inner ends of the rods (21, 22) are connected to the axle part (18) and the connection is adapted to perform both push and pull forces upon the rods. One or more spring elements (23) are provided between at least one of the rods (21, 22) and the sound emitting surfaces (1).

Abstract: Acoustic transmitter in particular for use in offshore seismic explorations, having sound-emitting surfaces (1, 2) being adapted to be subjected to vibrational movement by means of a drive unit (21) through at least one push element (22A, 22B) and two plate-like end pieces (3, 4) which are connected to the sound-emitting surfaces. The sound-emitting surfaces are formed by two curved plate members (1, 2) being of comparable width and heigth dimensions. The end pieces (3, 4) have a generally rectangular shape with a first pair of opposing side edges connected (5, 6, 7, 8) to end portions of the plate members (1, 2). Another pair of side edges on each end piece (3, 4) as well as side edges of the plate members engage two side plates (9, 10) which at either side closes the acoustic transmitter, preferably in a tightly enclosing manner.

Abstract: Flextensional acoustic source with sound-emitting surfaces (1, 2, 3, 4) adapted to be excited into vibrational movement, and for use in seismic exploration at sea. The source comprises a drive unit (21) being through the intermediary of at least one push element (22A, 22B) adapted to impose vibrational movement to the sound-emitting surfaces. Between at least one push element (22A, 22B) and the associated sound-emitting surface(s) (1, 2, 3, 4) there is provided a non-linear spring element (27, 28) the spring constant of which is controllable. Two oppositely acting push elements (22A, 22B) are arranged in axial alignment and preferably centrally in the source, and in addition thereto there are provided at least two tension elements (39, 40) with associated controllable, non-linear spring elements (35, 36, 37, 38) and being coupled to the sound-emitting surfaces (1, 2, 3, 4).

Abstract: A drive system for acoustic devices comprising drive devices, the projecting driving studs (14,15) of which are connected to pressure beams (27,28) of the acoustic device, the drive devices comprising a fixture frame (26) inside of which there are located drive units with an intermediate mechanical prestress device (22,23,24,25), the drive units comprising stator and drive cells stacked by means of guide rings (4,5) and guide discs (11), the stator cell comprising a magnetizing coil (1) with a surrounding tube (2) of soft-magnetic material fixed inside a fixture tube (3), and the drive cell comprising a cylindrical magnetic pellet (6) , discs of soft-magnetic material (7,8) and of permanent-magnetic material (9,10) making contact with said magnetic pellet.

Abstract: A drive package for acoustic transmitters includes a frame (6) of magnetic material with windows for accommodating driving members (20) and prestress devices (22) . Two windows with driving members and an intermediate window with a prestress device form a column which, by way of pressure studs (24) in the driving members and holes (14) in the frame, clamp pressure rods (4) located inside the transmitter against the shell (1) of the transmitter. The drive package may include several columns.

Abstract: A driving member for a diaphragm in acoustic devices includes a body with opposite recesses into which driving rods are inserted. One end of the driving rods is attached to pressure rods which directly influence the diaphragm and the other end of the driving rods makes contact with the bottom of the recesses.