Abstract: In one embodiment the invention comprises a particle velocity sensor that includes a housing with a geophone mounted in the housing. A fluid that substantially surrounds the geophone is included within the housing. The particle velocity sensor has an acoustic impedance within the range of about 750,000 Newton seconds per cubic meter (Ns/m3) to about 3,000,000 Newton seconds per cubic meter (Ns/m3). In another embodiment the invention comprises method of geophysical exploration in which a seismic signal is generated in a body of water and detected with a plurality of co-located particle velocity sensors and pressure gradient sensors positioned within a seismic cable. The output signal of either or both of the particle velocity sensors or the pressure gradient sensors is modified to substantially equalize the output signals from the particle velocity sensors and the pressure gradient sensors. The output signals from particle velocity sensors and pressure gradient sensors are then combined.

Abstract: An optical accelerometer includes a beam and at least one optical fiber affixed to one side of the beam such that deflection of the beam changes a length of the optical fiber. A device for sensing the change in length of the optical fiber is functionally coupled to the at least one fiber. A seismic sensor system includes at least two accelerometers, oriented such that their sensitive axes are at least partially aligned along mutually orthogonal directions. Each accelerometer includes a beam, and at least one optical fiber affixed to one side of the beam such that deflection of the beam changes a length of the at least one optical fiber. A device for sensing the change in length of the optical fiber is functionally coupled to the at least one fiber of each accelerometer.

Abstract: A method for operating a marine seismic survey system includes deploying from a seismic vessel at least two lead-in cables each functionally coupled at one end thereof proximate a respective paravane. The lead-in cables have at least one spreader cable functionally coupled between the paravanes. Strain is measured at least one position along each lead in cable; and a length of each cable is adjusted such that the measured strains are substantially equal.

Abstract: Physical parameters are measured for an array of seismic sources, preferably for each activation of the seismic sources. Calibration functions are obtained and the measured physical parameters and calibration functions are applied to a model, which generates a calibrated source signature for the array of seismic sources. Alternatively, the measured physical parameters are applied to a model, which generates a modeled source signature, and then the calibration functions are applied to the modeled source signature to generate the calibrated source signature. Alternatively, modeled source signatures are generated for each seismic source and then the calibration functions are applied to the modeled source signatures to generate a calibrated source signature for each seismic source. Then the calibrated source signatures for each seismic source are combined, preferably by linear superposition, to generate the calibrated source signature for the array of seismic sources.

Abstract: A system and method for pre-stack imaging system that includes multiple processors, with each processor configured to perform two-way wave equation-based forward wave propagation of a source event to obtain a source wave field using high order spatial finite differences for a shot gather, and to perform two-way wave equation-based backward wave propagation of received waves to obtain a receiver wave field using high order spatial finite differences for the shot gather; and to correlate the source and receiver wave fields to obtain an image region.

Abstract: A seismic streamer stretch section includes at least one spring member. The section includes means for coupling the at least one spring member at each end to at least one of a seismic streamer and a seismic lead in cable, and a cable coupled at its ends to the means for coupling. The cable is capable of carrying electrical and/or optical signals. The cable is formed such that it undergoes substantially no axial strain when the spring member is elongated.

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: A marine seismic streamer steering device comprises at least two hinged sections pivotally coupled to each other and connected between two adjacent sections of the seismic streamer, and a bend control unit that controls bending of the hinged sections relative to the longitudinal axis of the seismic streamer. The steering device further comprises a roll sensor which determines rotational orientation of the body and transmits the orientation to the bend control unit, a lateral position sensor which determines lateral position of the body and transmits the lateral position to the bend control unit, and a depth sensor which determines depth of the body and transmits the depth to the bend control unit. The bend control unit then controls the bending of the hinged sections based on the transmitted rotational orientation, lateral position, and depth of the body.

Abstract: A method is disclosed for amplitude preserving Kirchhoff time migration. The method includes calculating estimates of the geometrical spreading terms using a constant velocity approximation. Takeoff and emergence angles are accurately calculated based on a model of velocity which varies with respect to travel time. An image can be calculated at at least one travel time using the estimated weights and calculated takeoff and emergence angles.

Abstract: A helipad motion compensation system for a vessel includes at least one controllable length actuator operatively coupled between the helipad and the vessel. The system also includes an attitude sensor disposed on at least one of the helipad and the vessel. The sensor produces signals corresponding to change in attitude of the helipad. A controller is in operative communication with the sensor and is arranged to operate the at least one actuator. The actuator is operable to substantially maintain an attitude of the helipad to compensate for motion of the vessel.

Abstract: An optical fiber sensor array is disclosed which includes a first sensor fiber and a first reference fiber coupled at one end thereof to one side of a first optical coupling. A first wavelength selective reflector is coupled to the other end of each of the first sensor fiber and the first reference fiber. A second sensor fiber is coupled at one end to one side of a second optical coupling. The other side of the second optical coupling is coupled to an opposite side of one of the first wavelength selective reflectors coupled on one side to the first sensor fiber and the first reference fiber. The array also includes a second wavelength selective reflector coupled to the other end of each of the second sensor fiber and the second reference fiber. The second wavelength selective reflectors are operative at a wavelength different from an operative wavelength of the first wavelength selective reflectors.

Abstract: A seismic streamer cleaning device includes a means for converting motion of water past a seismic streamer into movement of the device as the streamer is towed through the water. A cleaning element is cooperatively engaged with the device and an exterior surface of the streamer. In one embodiment, the cleaning element includes brush bristles.

Abstract: An apparatus for making a marine seismic streamer includes a conveyor for transporting assembled mechanical harness from a storage device therefor to a storage device for storing completed marine streamer. The apparatus includes a first extruder for filling the harness with a void fill material and a second extruder for depositing jacketing material onto the filled harness both extruders being intermediate the two storage devices. A means for changing state of the void filling material is disposed proximate an outlet of the first extruder. In one embodiment, the means for changing state includes a radiation source.

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: A method is disclosed for deghosting seismic data. The data include measurements of a vertical component of particle motion and pressure. The measurements are substantially collocated and made at a plurality of spaced apart positions. The method includes transforming the data into the spatial frequency domain, and separating upgoing and downgoing wavefield components of the transformed data. Water surface multiples may also be removed by decomposing the signals made at a plurality of seismic energy source locations into upgoing and downgoing wavefields.

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: A method is disclosed for processing seismic data. The method includes prestack depth migrating the seismic data to generate common image gathers using an initial velocity-depth model. Horizons in the migrated seismic data are selected. Residual migration velocity analysis in the depth-offset domain is performed with respect to each selected horizon, and the velocity-depth model is updated based on the residual migration velocity analysis.

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: A method is disclosed for attenuating noise in seismic data. The method includes calculating a trace envelope for at least part of at least one seismic trace, generating a filtered envelope from the trace envelope, and transforming the filtered envelope to a filtered trace. In one embodiment, a length of a filter operator used for generating the filtered envelope is inversely related to a maximum frequency to be preserved in the filtered trace.

Abstract: System for controlling cables and streamers in a seismic tow arrangement comprising at least one deflector (13) connected to one side of a tow vessel (10) via at least one wire (12), leading or the like, wherein the deflector is located in a position at a distance perpendicularly to the direction of movement (5) of the tow vessel, the vessel being equipped with a navigation system for measuring the position of the vessel. The system is characterised by comprising a command unit and a number of control units, where the control units are located on at least some of the streamers and are adapted to measure and report about their positions, that the command unit comprises means for receiving the position information from each individual control unit and calculation of possible deviations from predetermined positions, and that the system comprises means for changing the position of the streamers for re-establishing the positions of the control units.