Abstract:
A system and method for generating acoustic source energy in marine seismic operations. A plurality of acoustic energy sources are integrated within seismic streamers to facilitate deployment, power distribution and signal communication. The acoustic energy sources can comprise slotted cylinders activatable with piezoelectric elements. By providing an array of lightweight, energy efficient acoustic energy sources throughout a seismic receiver array, both zero-offset and far-offset reflection data can be recorded. The acoustic energy discharge can be swept over a time interval, or steered in a selected pattern throughout the array, to significantly reduce the impulse energy released into the water. The reflected signals can be compressed back into an impulse for subsequent data processing. Bi-static reflections can be generated simultaneously with the zero-offset source-receiver locations to improve the vertical and horizontal resolution of data.
Abstract:
A marine seismic fiber optic acoustic sensor system having internal mirrors with a low reflectivity written into the fiber to form a series of continuous, linear sensors incorporated in a single fiber, each sensor bounded by a pair of internal mirrors. A pulsed laser provides optical signals to the fiber at a pulse width less than twice the travel time to assure that there will be no phase or frequency modulation of signals returned from the sensors and reflected optical energy is returned through the same fiber to an optical coupler where it is input to a compensating interferometer to produce interference signals which are then time division multiplexed to produce signals corresponding to acoustic signals received by each mirror bound sensor. Calibration to remove local temperature effects is provided by using a desensitized reference fiber with internal mirrors identical to the sensitized fiber, by a piezoelectric stretcher built into the fiber or any other conventional calibration technique.
Abstract:
A structure and method for constructing a non-oil-filled towed array providing a single cable entry point for each channel irregardless of the number of hydrophones used to make up a hydrophone group or array is described. 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 addition of hollow micro-spheres into a Reaction Injection Molded (RIM) polyurethane material used to mold the hydrophones. Additional buoyancy may be desired adjacent heavier cable sections where connectors and telemetry modules are located. An embodiment enables precise adjustment of hydrophone cable buoyancy by providing precise adjustment of the concentration of hollow glass micro-spheres in areas where more or less buoyancy is desired.
Abstract:
A support structure of hydrophones for a towed array sonar system includes elastic members arranged in each sensor package and adapted to support a hydrophone received in the sensor package while attenuating vibrations transmitted to the sensor package. External vibrations, such as vibrations generated due to the running of a towing vessel or vibrations induced due to motions of a towing cable, which are irrespective of acoustic waves reflected by a target moving underwater, are attenuated by the hydrophone support structure during the transmission thereof from the sensor package to the hydrophones, so that the hydrophones are suppressed from vibrating due to the external vibrations. Accordingly, it is possible to reduce noise included in output signals of the hydrophones, thereby achieving an improvement in the sensing performance of the towed array sonar system.
Abstract:
The present invention is directed to a hydrophone streamer towable from a marine vessel on a body of water. The hydrophone streamer comprises a plurality of hydrophones electrically connected in parallel. Each hydrophone further comprises a normally-closed pressure activated switch connected in series with a hydrophone sensor. Each pressure switch is calibrated to open at a predetermined depth in the body of water thereby disabling the associated sensor without affecting operation of other hydrophones in the streamer.
Abstract:
A restraint use in a flotation apparatus having components, such as tubular member and couplings, includes a cord having a first end and a second end. Each of the ends is connected to a component. Preferably, the cord is run internally within a tubular member and connects two couplings that are fitted onto opposing ends of the tubular member. The cord has a breaking strength at least sufficient to restrain a coupling when the connection between the coupling and the tubular member is compromised such as when a coupling explosively releases from the tubular member. A method for assembling and operating a floating apparatus includes connecting a coupling to a stationary member, such as a second coupling, using a cord. The method can also include configuring the cord to have a breaking strength that is at least sufficient to restrain a coupling when the connection between the coupling and the tubular member is compromised such as when a coupling explosively releases from the tubular member.
Abstract:
A support structure of hydrophones for a towed array sonar system includes elastic members arranged in each sensor package and adapted to support a hydrophone received in the sensor package while attenuating vibrations transmitted to the sensor package. External vibrations, such as vibrations generated due to the running of a towing vessel or vibrations induced due to motions of a towing cable, which are irrespective of acoustic waves reflected by a target moving underwater, are attenuated by the hydrophone support structure during the transmission thereof from the sensor package to the hydrophones, so that the hydrophones are suppressed from vibrating due to the external vibrations. Accordingly, it is possible to reduce noise included in output signals of the hydrophones, thereby achieving an improvement in the sensing performance of the towed array sonar system.
Abstract:
A floatation device for marine seismic energy sources. The floatation device includes one or more tubular members and a plurality of couplings for sealing and coupling the tubular members to one another. The couplings include an air valve for filling the tubular members with air. One or more marine seismic energy sources are preferably coupled to and supported by the floatation device.
Abstract:
A sensor array cable and method of construction thereof utilizing a sensor/interlink assembly to facilitate the relatively easy and inexpensive installation of a sensor device in a cable that includes a strength member to provide tensile strength to the cable, optical fibers or wires for carrying electrical or optical energy to and from the sensor device, and a protective outer jacket. A portion of the protective outer jacket is removed allowing access to the inner strength member and optical fibers. A segment of the strength member is removed and an interlink/sensor assembly is installed in its place. The interlink serves to maintain the tensile strength of the cable. Optical fibers and/or electrical wires are connected to the sensor device for operation. The interlink/sensor assembly and associated optical fibers and electrical wires are then enclosed in an overmold which is sealed to the outer protective jacket.
Abstract:
An arcuate or flat ferroelectric sensor is incorporated in a seismic streamer. The structure comprises an interior cable, a surrounding woven strength member, an overlying foam floatation layer, and an enclosing jacket. One or more elongate channels are formed in the overlying floatation layer, and one or more hydrophones are mounted in the channel(s). The elongate channel enlarges the acoustic aperture for the reception of seismic signals.