A method for determining seismic sensor depths in a body of water includes accepting as input to a computer measurements of seismic signals made by a plurality of seismic sensors disposed in a body of water. A depth increment and a range of sensor depths for correlation of signals from each of the plurality of seismic sensors is defined. In the computer, the input seismic measurements are extrapolated to each depth increment in the range. A depth of each seismic sensor is determined by correlating the seismic signal measurements with depth-extrapolated measurements of the seismic signal measurements.

An invention that relates to streamers is described. These streamers contain one or more streamer sections. These sections can have sensors, channels, and/or analogue arrays of sensors are disposed along its length. At least one of these streamer sections has a variable density of sensors, channels, and/or analogue arrays along the length.

Calibration based on twist and orientation for towed object can include determining an amount of twist as a function of length of a portion of a towed object based on output of tilt sensors in the portion of the towed object and a model that describes the twist along the portion of the towed object. An orientation of a seismic sensor can be determined based on the determined amount of twist and a position of the seismic sensor along a length of the portion of the towed object. The seismic sensor can be calibrated based on the orientation.

A submersible node and a method and system for using the node to acquire data, including seismic data is disclosed. The node incorporates a buoyancy system to provide propulsion for the node between respective landed locations by varying the buoyancy between positive and negative. A first acoustic positioning system is used to facilitate positioning of a node when landing and a second acoustic positioning system is used to facilitate a node transiting between respective target landed locations.

A submersible node and a method and system for using the node to acquire data, including seismic data is disclosed. The node incorporates a buoyancy system to provide propulsion for the node between respective landed locations by varying the buoyancy between positive and negative. A first acoustic positioning system is used to facilitate positioning of a node when landing and a second acoustic positioning system is used to facilitate a node transiting between respective target landed locations.

The present disclosure is directed to systems and methods of facilitating a seismic survey and locating seismic data acquisition units in a marine environment. The system can include a first seismic data acquisition unit. The first seismic data can include a cleat ring to couple the first seismic data acquisition with a second seismic data acquisition unit. The system can include a rope having a first end coupled to a first portion of the first seismic data acquisition unit and a second end coupled to a second portion of the first seismic data acquisition unit. The system can include a cavity formed by the cleat ring. The system can include a telltale component coupled to a portion of the rope. The rope and the telltale component can be stored in the cavity of the first seismic data acquisition unit.

A method for conducting a seismic survey for collecting seismic data off shore. It comprises a first seismic survey providing a first set of data for an area using individual seismic sub-source arrays (2). It further comprises a second seismic survey of the same area for providing a second set of data. The individual seismic sub-source arrays (2) are similar to the sub-source arrays used during the former survey and are arranged in more than two shot-unit sources (3). Each shot-unit source (3) comprises a pair of neighboring individual seismic sub-source arrays (2) arranged to be fired substantially at the same time.

A sub-bottom geophysical imaging apparatus includes a carriage assembly having at least one acoustic transmitter, and at least one acoustic receiver proximate the transmitter. A position determining transponder is mounted on the carriage. A plurality of position transponders is disposed at spaced apart positions to communicate with the transponder mounted on the carriage. A pair of tracks is provided for moving the carriage to selected positions above the bottom. Electrodes are provided for a resistivity sensor and a shear acoustic transmitter and receiver disposed in at least one of the pair of tracks. A signal processing unit is configured to coherently stack and beam steer signals detected by the line array, the electrodes and the shear transmitter and receiver. The signal processing unit is configured to record signals detected by the line array of acoustic receivers, the electrodes and the shear acoustic transmitter and receiver.

The present invention discloses a near-sea-bottom hydrate detection system, which includes a ship-borne part and a deep-towing part. The ship-borne part includes: a comprehensive monitoring host, configured to send an acquisition triggering pulse signal, and transmit the signal to the deep-towing part; and receive near-sea-bottom information acquired by the deep-towing part, and determine a near-sea-bottom condition according to the near-sea-bottom information. The deep-towing part includes: a data acquisition unit, configured to acquire near-sea-bottom information at a current position according to the acquisition triggering pulse signal; an electric spark vibration source, configured to generate an electric spark vibration signal according to the acquisition triggering pulse signal; and a multi-channel data-acquisition electronic cabin, connected to the comprehensive monitoring host, the data acquisition unit, and the electric spark vibration source separately, and configured to transmit the acquisition triggering pulse signal to the electric spark vibration source and the data acquisition unit, and transmit the near-sea-bottom information acquired by the data acquisition unit to the comprehensive monitoring host. In this way, the Fresnel radius can be reduced, and the detection resolution can be improved.

A proposed geometrical distribution for a first non-impulsive source and a second non-impulsive source of a source array can be received. A near-field-to-notional computation can be performed for the proposed geometrical distribution to yield a respective computed notional output of the first and second non-impulsive sources. Whether the computed notional output of the first non-impulsive source has a first amount of residue greater than a threshold amount of residue can be determined. Whether the computed notional output of the second non-impulsive source has a second amount of residue greater than the threshold amount of residue can be determined. An indication whether either of the first or second amounts of residue is less than or equal to the threshold amount of residue can be provided.