Abstract:
A hydrophone streamer that includes several arrays of optical fiber pressure sensors. Each array consists of at least three sensors symmetrically disposed around the inside of the streamer skin to form a vertically-disposed array. Each sensor modulates a coherent light beam in accordance with the instantaneous ambient water pressure. The output signals of the sensors include an AC component due to seismic waves and a DC component due to hydrostatic pressure difference between the sensors of an array. Means are provided to resolve the AC and DC components to determine the arrival direction of the received seismic waves.
Abstract:
A construction and method of producing an elongated underwater acoustic array includes a plurality of interconnected hydrophones and circuit modules protected by a plastic foam cushioning sheath, covered with a tough, essentially acoustically transparent hose-like jacket and containing a plurality of aramid fiber ropes as strength members to carry the tensile loads on the array. An elongated tube-like fabric retaining member is interposed between the sheath and the exterior hose jacket which is longitudinally stitched to provide a plurality of spaced parallel tubes, each of which is of just sufficient diameter to contain one of said strength members. The strength members are terminated at a connector at each end of the array, and a spacer member is placed near each connector to spread the strength member ropes to the desired diameter. The spacer members and the adjacent ends of the retaining members are each cemented to the strength member ropes.
Abstract:
An acoustic line array which includes a co-axial cable having a center coctor surrounded by a flexible material of low-electrical conductivity. The flexible material is surrounded by a conducting material protected by an external shield. The cable has characteristic impedance which is sensitive to pressure variations in the medium due to a traveling acoustic pressure wave from an acoustic source. Variations in the impedance of the array are used to detect the acoustic source. Alternatively, the line array makes use of discrete sensors placed at suitable intervals along the array. This type of acoustic array eliminates the use of a plurality of wires carrying the electrical signals from the transducer to the storage equipment and elaborate multiplexing techniques.
Abstract:
A marine seismic streamer section for a towed underwater streamer containing a buoyancy regulating fill liquid and the usual hydrophones, strain cables, signal wires and the like housed in a generally cylindrical tubular jacket sealed at its ends against loss of fill liquid and containing a depth sensor for producing electrical signals indicative of the depth of the streamer. The sensor is in a rigid housing whose interior is connected by a tube to a valved calibrating chamber having a valve member normally communicating the interior of the depth sensor housing to the fill liquid pressure conditions in the jacket. The chamber has an external access port normally closed by a plug, and the valve member is movable by a probe inserted through the port when the plug is removed and a source of gauged pressure connected to the access port to subject the interior of the depth sensor housing to the gauged pressure source.
Abstract:
A transducer including a central core extending along one axis and having a length along the axis defined as xl, where x is at least two and l is any given length. Surrounding the central core are a plurality of n wires, where n is an even integer of four or more. Each of said wires is wound around different portions of the core to form x numbers of coils of a length of l/n. These coils are a distance of l apart, center to center. Appropriate packaging of this transducer permits burial. The ends of the transducer may be connected to electronic analyzing equipment for processing of signals generated by objects approaching the transducer.
Abstract:
A land surface seismic prospecting cable which can be towed on the surface of the earth along seismic survey lines. The cable is used to transport, position, protect, house, or attach sensors used for making geophysical and environmental measurements. The cable apparatus may comprise a plurality of segments each interconnected by an electrical connector and each segment having a plurality of sensors associated therewith. The outputs of the signals from the sensors are carried by way of a multiconductor wire cable within the seismic cable to a seismic recorder. After an acoustic disturbance is produced and the seismic information is recorded, the towed land cable or land streamer is towed intact to the next shooting site which saves a great deal of time and allows greater areas to be covered in a predetermined time period.
Abstract:
A neutrally buoyant seismic hydrophone streamer is constructed by extruding a syntactic foam material comprising an elastomeric material and gas filled microspheres onto a central stress member to form an elongated streamer member. The streamer may then be covered with a suitable water and oil resistant, abrasion resistant covering and be provided with exteriorly affixed hydrophones, or hydrophones can be affixed to the foam core and an outer protective sheath can be extruded or otherwise provided around the streamer and the hydrophones to provide a uniform diameter streamer assembly. Extrusion is effected utilizing a suitable elastoplastic material which can be extruded at pressures below about 300 psi to avoid bursting the gas filled spheres of the syntactic foam.
Abstract:
A hermaphrodite connector for seismic cables having an interrupted threaded collar for fastening the two halves of the connector, one part of the interrupted thread being female and one part being male. The connector also includes means preventing any misalignment while engaging the two halves by incorporating full 360* pin protection in each connector half.
Abstract:
A multi-section marine seismic streamer construction wherein each streamer section has identical couplers at opposite ends. The couplers have a partly separable cylindrical end portion interfitted in the streamer outer jacket and clamped about a strain cable anchor head and an end portion of a trunk cable running through the section. The couplers also have semicylindrical portions to mate with like portions of campanion couplers along a diametric plane of the streamer, with male and female electrical plugs in plug cavities in the mating portions coupled together, and mounting bolts perpendicular to the diametric plane securing the mating portions together.
Abstract:
In accordance with an illustrative embodiment of the present invention, a marine streamer cable of layered solid construction includes a cable core with a stress member and electrical conductors extending eccentrically within a tubular flotation body. Seismic transducer assemblies are provided at spaced points along the cable with each assembly including a rigid case construction that houses a disc-type hydrophone to the side of the core and within the circumferential outline of the flotation body.