Abstract:
Methods and apparatus for cable termination and sensor integration at a sensor station within an ocean bottom seismic (OBS) cable array are disclosed. The sensor stations include a housing for various sensor components. Additionally, the sensor stations can accommodate an excess length of any data transmission members which may not be cut at the sensor station while enabling connection of one or more cut data transmission members with the sensor components. The sensor stations further manage any strength elements of the cable array.
Abstract:
An electronic-carrying module (640), for example for use with a seismic data acquisition cable (400), is disclosed. The preferred electronic-carrying module (640) includes, first, an electronics carrier (106) having access means (107) for providing an easy-to-reach access to wrap-around circuitry fitted inside a curved space (104a) within the electronics carrier (106). Second, a pair of rigid end-fittings (102) spaced apart axially by the electronics carrier (106) for connecting to a section of the seismic data acquisition cable (400). And third, an axial hole (100) formed in the electronics carrier (106) and the rigid end-fittings (102) defining the curved space (104a) between the axial hole (100), the access means (107) and the rigid end-fittings (102).
Abstract:
A seismic sensor cable is disclosed. The cable includes an outer jacket disposed on an exterior of the cable. The outer jacket excludes fluid from entering an interior of the cable. A reinforcing layer disposed within the outer jacket, which includes at least one electrical conductor disposed therein. An inner jacket is disposed within the reinforcing layer, and at least one electrical conductor disposed within an interior of the inner jacket. Some embodiments include at least one seismic sensor electrically coupled to the at least one electrical conductor disposed in the reinforcing layer In some embodiments a housing is disposed over the electrical coupling of the sensor to the conductor. The housing is molded from a polyurethane composition adapted to form a substantially interface-free bond with the cable jacket when the polyurethane cures.
Abstract:
An array of fiber optic hydrophones or geophones is formed by winding of optical fiber around a continuous, yet flexible cylindrical core. The cylindrical core contains an elastomer filled with a specified percentage of voided plastic microspheres. The elastomer provides the necessary radial support of the optical fiber, and with the included voided microspheres, provides sufficient radial compliance under acoustic pressure for proper operation of the hydrophone. The cylindrical core can be made in very long sections allowing a plurality of fiber optic hydrophones to be wound onto it using a single optical fiber, with individual hydrophone elements separated by integral reflectors such as Fiber Bragg Gratings (FBSs). The center of the core may include a strength member and a central hollow tube for the passing of additional optical fibers. The aforementioned hydrophone array is then packaged within a protective outer coating or coatings as required for the specified application.
Abstract:
The present invention relates to a cable section assembly for marine applications having a core structure, such as a buoyant cable antenna interim manufacturing step subassembly, and a protective casing formed from a heat shrinkable tubing which together with the interim subassembly forms a complete assembly. For buoyant cable assembly applications the interim subassembly is at least partially formed of polyurethane material having glass microballoons distributed therein, with such material in any event occupying an outer layer portion of the subassembly. The cable section assembly of the present invention is formed by providing a length of heat shrinkable flexible tubing, inflating or expanding the heat shrinkable tubing to its approximate full diameter, inserting the core structure into the length of tubing, and shrinking the tubing around the core structure.
Abstract:
The invention relates to low-frequency underwater detection systems comprising a towed linear antenna (12, 13).It consists in producing the transducers of the transmission antenna (12) in the form of flextensional arrays of cylindrical type (20) and in forming directional transmission channels covering all of space.It makes it possible to lighten the assembly and to facilitate implementation at sea, which becomes able to be automated.
Abstract:
An acoustic emitter for coupling in series in a marine seismic streamer is provided with an annular housing and an annular piezoelectric emitting element positioned coaxially within the housing. This form of construction permits the electrical or electro-optical transmission line which normally runs along the axis of the streamer to pass through the center of the emitting element, while also permitting the emitter to be spooled with the streamer.
Abstract:
A preferred seismic survey system includes a cable having a sensor unit. The sensor unit includes sensors for detecting acoustical energy (e.g., shear and/or pressure waves) and is disposed in a decoupling device that substantially acoustically uncouples the sensor unit from the cable. One preferred decoupling device includes relatively flexible tension members that isolate the sensor unit from acoustical-energy related movement of the cable. A fastening member, which is optionally formed of vibration absorbing material, affixes the sensor unit to the flexible member. Optionally, a spacer adjusts the resonant frequency of the tension member and a resilient tube encloses the decoupling device. One preferred seismic survey method includes connecting the sensor unit to a cable with a decoupling device that substantially acoustically uncouples the sensor unit from the cable; and positioning a sensor unit on a seabed such that the sensor unit is acoustically coupled to the seabed.
Abstract:
In one aspect the invention comprises a system and a method for marine geophysical exploration, which includes a first cable connected to a vessel and a plurality of streamer cables connected to the first cable. The first cable includes all towing strength members and all electrical power and data transmission conductors for the connected streamer cables.
Abstract:
An structure and method for constructing a non-oil-filled towed array providing a single cable entry point for each channel regardless of the number of hydrophones used to make up a hydrophone group or array. The method and apparatus enables uniform buoyancy of the hydrophone array and the primary cable around which the hydrophone array is wound. Uniform buoyancy is achieved through the selective addition of hollow micro-spheres into a Reaction Injection Molded (RIM) polyurethane material used to mold the hydrophones. For example, additional buoyancy may be desired adjacent heavier cable sections where connectors and telemetry modules are located. The preferred method and apparatus enables precise adjustment of hydrophone cable buoyancy by providing precise adjustment of the concentration of hollow glass microspheres in areas where more or less buoyancy is desired. Use of the preferred Reaction Injection Molding (RIM) method and apparatus of the present invention, results in significant reductions in cost and time in the construction of solid towed arrays. The RIM material enables use of a softer, lower durometer matrix in which the micro-spheres reside resulting in a hydrophone cable that is more flexible than prior known construction methods. For example, the prior known methods provide a minimum bending radius of 6 feet, whereas the method and apparatus of the present invention provide a minimum bending radius of 18 inches, which enables wrapping of the preferred hydrophone cable around a primary towing cable.