Abstract:
A weight block for a marine seismic cable comprises a heavy weight member with a soft, overlying layer. The weight block is bolted, hinged, or otherwise attached to the cable to provide desired ballast. The outer covering of the weight block is molded over the inner metal member with an injection molding machine or other standard techniques. The inner diameter of the molding on the block may have a plurality of ribs with a smaller diameter than the nominal diameter of the solid-filled or liquid filled cable.
Abstract:
The disclosure relates to a signal processing method for a towed linear antenna, notably to resolve right-left ambiguity, said antenna comprising a set of hydrophone multiplets each with nnull3 hydrophones spread over a straight section of the longitudinal axis of said antenna, wherein the roll angle of each multiplet relative to the vertical is measured, the signals of said hydrophones and said roll angles are used to synthesize pnull3 linear sub-antennas, then M azimuth channels are formed with each sub-antenna and 2 adaptive right-left channels are formed from said p sub-antennas for each direction corresponding to each azimuth channel. The invention resolves right-left ambiguity with optimal performance in detection and for long antennas.
Abstract:
A method for wrapping continuous strands of steel wire about a seismic cable including interconnected sensor sections and conductor sections where a cross sectional diameter of the sensor section is at least four times that of the conductor section. Two layers of armoring are provided with a first layer wrapped in a first angular direction opposite that of the second layer. A stranding assembly is provided which has two selective positions, one for providing a die hole for stranding the conductor section, another for providing a passage hole for allowing the sensor section to pass after wrapping with armor wire.
Abstract:
A gel-filled seismic streamer containing a hydroplane housing which isolates a hydrophone element from shear waves and mechanical forces but sensitive to pressure waves. In one embodiment, the gel-filled streamers contains a hydrophone housing with an air pocket at each end for isolating a pressure sensitive hydrophone element from mechanical noise generated by cable movement during seismic data acquisition operations. The hydrophone housing further provides a protective case to isolate a pressure-sensitive hydrophone element from shear waves. An inlet formed in the protective hydrophone housing enables pressure waves to be communicated to the pressure sensitive hydrophone element inside of the housing. In one embodiment, the pressure sensitive hydrophone element is a hollow gel-filled cylinder that expands radially outward into a second air gap formed in the housing. A protective case is also provided to isolate the hydrophone housing from shear waves. An alternative hydrophone housing for deployment inside of a streamer is also disclosed which fixably positions a positioning hydrophone or seismic hydrophone within the housing using rubber supports.
Abstract:
The present invention provides an underwater cable arrangement includes an underwater cable having one or more external devices mounted on the cable. In one form of the invention, the external devices are powered primarily or entirely by inductive coupling between a coil disposed in the cable and a coil disposed in the external device. The invention also provides a variety of external devices capable of use with an underwater cable. The invention further provides a coil support arrangement for supporting a coil within an underwater cable in a manner protecting a core of the coil from damage.
Abstract:
A support structure for piezoelectric elements in a marine seismic cable is provided. The support structure comprises upper and lower cylindrical halves, each with channels formed therein. Two axial channels are adapted to retain three piezoelectric elements each. A third axial channel, positioned between the sensor element channels, is adapted to retain a flexible circuit. Transverse channels between the sensor element channels and the circuit channels accommodate extension from the flexible circuit. The piezoelectric elements are mounted within their respective channels with a resilient pad with adhesive on both sides. The piezoelectric elements are graded so that any group of three piezoelectric elements exhibits approximately the same sensitivity as any of the other three groups of piezoelectric elements on the support structure.
Abstract:
A system for gathering and recording seismic data. The system provides cable sections having takeouts at predetermined locations for connection to a string data module and attached sensor string. Additional data strings can be connected to vary the sensor orientation and spacing at different positions within a seismic array. Data is collected by sensors attached to each sensor string and is transmitted through the corresponding string data module and to an intermediate data manager. The data is transmitted at a high delivery rate to a master recording unit. Transverse data managers can be connected in large arrays between intermediate data managers and the master recording unit to provide additional control or data processing attributes, and local recorders can provide data processing and transmission attributes before the data is transmitted to the master recording unit. The system architecture contains multiple levels of data paths each having successively higher data rates. Multiples of lower paths feed into the higher paths and multiples of these paths feed into successively higher data paths. Each level of the data path architecture can stand alone such that each level provides line transmission functions asynchronously to the other levels.
Abstract:
An integrated ocean bottom towed four-component array for seismic data acquisition consists of a four-channel electronic section for seismic data collection, a gimbaled three-component geophone and a hydrophone in a housing. The array connects with a submarine cable through a cable joint in order to acquire four components of data consisting of seismic P wave, shear wave and hydrophone in total. Through cable data transmission and processing in a central station, ocean bottom oil and gas structure information can be obtained. Because of the high SNR acquisition in the ocean bottom seismic data acquisition of the present invention, and the waterproof cable interconnections between each of the sections of the present apparatus, data acquisition of high quality can be gained to realize highly efficient and easy ocean bottom towing operations.
Abstract:
A telemetry harness for a hydrophone array which carries and positions the signal carrying elements of the array for ready assembly and reconfiguration. An elongated fabric incorporates bare optical fibers as well as optical and electrical cables and tension-resistant strength members. The fiber is characterized by markings, fiber slackness and apertures at predetermined locations that assist an assembler in determining where to cut selected bare fibers for splicing. The harness is wrapped around a layer of open cell foam that surrounds the aligned and linked sensors of an array segment with the resultant locations of the various sensors in resultant registration with the appropriate overlying fibers of the harness.
Abstract:
The present invention relates generally a method and apparatus for adjusting the buoyancy of towed seismic arrays comprising a plurality of streamers and specifically to the dynamic buoyancy control of the buoyancy of a towed array of streamers by means of applying current to electroactive polymers (EAP) incorporated within the towed array of seismic streamers. The bulk density of the streamer array is electrically altered to accomplish neutral buoyancy for a towed array of streamers within the full range of water-densities from fresh to extremely dense seawater.