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.

Abstract: A merged-mask micro-machining process is provided that includes the application of a plurality of layers of masking material that are patterned to provide a plurality of etching masks.

Abstract: An acoustic sensor array may include sensor sections positioned along a length of a strain member. One or more sensors may be disposed within a sensor section. One or more sensors may be encapsulated in a molding material using a reaction injection molding (RIM) process to form a sensor section. Buoyant sections may be formed between sensor sections on the strain member. Buoyant sections may be formed by encapsulating a portion of the strain member in a buoyant molding material using a RIM process. Buoyant sections and/or sensor sections may include hollow microspheres. A concentration of hollow microspheres may be adjusted to control a buoyancy of the array. The strain member, the sensor sections, and the buoyant sections may be joined to form the array.

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 marine acoustic source system has relativley densely packed energy sources arrayed in a tandem-like fashion along a horizontal plane. Preferably, a longitudinal axis of each source lies orthogonal to a pre-determined towing direction. The system includes protective tubes that encloses supply lines and auxiliary equipment, and a harness. The harness provides the primary mechanical connection for towing the sources through the water. To minimize bending of the supply lines, connectors having angular portions connect the sources to the supply lines. Further, the sources can be arranged such that source connection interfaces for receiving power, hydraulic fluid, or data point alternately in opposing directions. During use, the sources, e.g., air guns, are supported at a predetermined depth beneath the water's surface by a floatation buoy. Upon activation, the sources of a cluster each release individual air bubbles into the water.

Abstract: The present invention provides a method and apparatus of acquiring and processing seismic data. One or more controllers are each coupled to seismic sensors and to each other to form a network of data acquisition units. A main controller is coupled to a crossline unit via a cable comprising a synchronizing conductor and one or more power/data conductors. Commands and data are packaged such that multiple routings are possible without affecting final calculations. Each crossline unit is capable of accepting a fiber optic input, a wire input or a combination.

Abstract: A fiber optic acoustic sensor system including an optical conductor having low reflectivity mirrors is provided. Optical sensors are provided by sections of the optical conductor bounded by pairs of the low reflectivity mirrors. Pulses of light are injected into the optical conductor and reflected by the low reflectivity mirrors. The reflected pulses of light are processed using a compensating interferometer to generate interference patterns representative of the environmental conditions acting upon the optical conductor.

Abstract: The present invention provides a digital optical switch apparatus and process for manufacturing the apparatus. The apparatus includes a mirror assembly coupled to a top cap and to a bottom cap. The top and bottom caps each include one or more electrodes that, when energized with electrical energy, move a mirrored surface to one of a plurality of discrete positions. Mirror assemblies can be cascaded to create a packaged assembly having any multiple of discrete positions. The process includes planar micro-machining techniques to create isolated islands for electrical feed through. The process enables mechanical bonding of multiple tiers via a single bond region and through a bond-pad window.

Abstract: The present invention provides a pressure-balanced inertial valve assembly for use in marine seismic energy sources such as air guns. The valve includes a poppet having a first seal and a second seal. A pressure chamber containing a fluid under pressure communicating with the first and second seals to substantially balance the pressure across the seals. An inertial mass is coupled to the poppet. A coil assembly is disposed about the inertial mass. A central guide pin provides guided movement for axial translation.

Abstract: A flexible connector housing. The flexible connector housing includes a connector housing for receiving a pair of mating connectors. The connector housing further includes a spherical member that pivotally engages a cable housing.

Abstract: The present invention provides a vertical seismic imaging apparatus and method for evaluation a reservoir. The invention includes a plurality of sensors disposed in a well borehole either permanently cemented in place or retrievably disposed using a series of clamps to attach the sensors to the borehole wall. Each sensor uses one or more forced balanced controlled accelerometers to detect acoustic energy in the formation.

Abstract: A method for processing data from dual sensor receivers to produce a combined seismic trace. A first seismic trace is received from a geophone and second seismic trance from a hydrophone in a dual sensor receiver. This first and second seismic traces are transformed into a first and second seismic spectrum. The seismic spectrums are deghosted to obtain deghosted spectrums. The seismic spectra may be added to obtain a deghosted third spectrum. An inverse power is computed for each of the deghosted spectra. The inverse powers for each deghosted spectra are divided by sums of the deghosted spectra to obtain diversity filters. The first and third diversity filters are applied to the first seismic spectrum to obtain a scaled first seismic spectrum. The other scaled spectra are formed in a like manner. The diversity scaled seismic spectrum is inversely transformed to obtain the combined seismic trace.

Abstract: A two-conductor bidirectional digital telemetry interface between a seismic sensor acquisition/conversion module and a seismic data collection module. The data collection module is configured as a master electronics device and the sensor acquisition/conversion module is configured as a slave electronics device in the telemetry system. The master device provides power to the slave device over the two conductors. The master device transmits portions of commands to the slave device at a first time and the slave device transmits portions of a digital seismic data packet to the master at a different second time in a fixed-duration frame. The frames are transmitted at regular intervals. The outbound commands and inbound data are encoded by block codes. A phase-locked loop in the slave is locked to a master clock in the master by deriving a clock and a sync point from the block-coded commands it receives from the master.

Abstract: A device for controlling the position of an underwater cable comprises a body, first and second actuators, and a pair of wings. The body is stationarily mountable to the underwater cable and the first and second actuators are disposed in the body. Each wing has an axis of rotation and the wings are coupled to the first and second actuators to control the depth and the horizontal position of the underwater cable in the water.

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 method for processing data from dual sensor receivers to produce a combined seismic trace. A first seismic trace is received from a geophone and second seismic trance from a hydrophone in a dual sensor receiver. This first and second seismic traces are transformed into a first and second seismic spectrum. The seismic spectrums are deghosted to obtain deghosted spectrums. The seismic spectra may be added to obtain a deghosted third spectrum. An inverse power is computed for each of the deghosted spectra. The inverse powers for each deghosted spectra are divided by sums of the deghosted spectra to obtain diversity filters. The first and third diversity filters are applied to the first seismic spectrum to obtain a scaled first seismic spectrum. The other scaled spectra are formed in a like manner. The diversity scaled seismic spectrum is inversely transformed to obtain the combined seismic trace.

Abstract: A seismic data acquisition system includes a connector housing and a mating electrical circuitry module. A single interface couples electrical circuitry housed in the electrical circuitry module to one or more signal data carriers that are consolidated at a single location in the connector housing. Preferably, the connector housing and electrical circuitry module each have a substantially contaminant-free interior regardless of whether these two parts are mated. An alternate connector housing has two plug casings, each of which are provided with a plug. A complementary alternate electrical circuitry module includes two receptacles complementary to the plugs and an interior space for holding the electrical circuitry. A locking pin disposed within the plug casing selectively engages the electrical circuitry module.

Abstract: The present invention provides a method and apparatus of acquiring and processing seismic data. One or more controllers are each coupled to seismic sensors at to each other to form a line of data acquisition units. A main controller is coupled to a crossover line unit and to a power supply. Power and data control is distributed among the main controller, the crossover line controller, and each of the plurality of data acquisition units.

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: Disclosed is an accelerometer for measuring seismic data. The accelerometer includes a proof mass that is resiliently coupled to a support structure by folded beams, S-shaped balanced beams, straight beams, and/or folded beams with resonance damping. The support structure further includes travel stops for limiting transverse motion of the proof mass.